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HUBLER, DAVID KENNETH, Geoffrey Steward, and Benjamin Mills. "TREATMENT OF INDUSTRIAL EFFLUENT FOR ARSENIC, MERCURY, AND SILVER." Thesis, The University of Arizona, 2008. http://hdl.handle.net/10150/190458.
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Cross, Peggi. "Aqueous alpha-lipoic acid solutions for removal of arsenic and mercury from materials used for museum artifacts." Diss., The University of Arizona, 2007. http://hdl.handle.net/10150/195574.
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Recorded use of pesticides in the conservation of artifacts dates back to the 16th century. Museums today are faced with a tremendous task of identification and remediation of pesticides from artifacts in order to protect museum workers and the general public. In addition, artifacts are being repatriated by Native American tribes for use in cultural ceremonies which may subject the practitioner to health risks. Arsenic and mercury salts are among the pesticides that were used that are highly persistent and toxic. The primary challenge lies in removing these hazardous and persistent metals without damaging the materials or pigments on the objects.Concentrated aqueous alpha-lipoic acid solutions were developed for removing arsenic and mercury pesticides from materials commonly used in museum artifacts. The alpha-lipoic acid solutions were reduced using natural sunlight or laboratory ultraviolet lamps to enhance the binding of arsenic. The solubility of alpha-lipoic acid in various organic and inorganic solutions was determined and environmental parameters that impact the reduction and solubility, such as pH and temperature, were examined. The kinetics of the reaction of arsenic (III) with reduced lipoic acid was examined by varying the reduced lipoic acid, base and arsenic concentration as well as temperature and stirring conditions. The results indicated that the reaction occurs at a moderate rate primarily within 8 seconds in air. The reaction is chemically rate limited enhanced at higher temperatures and lower pH. Aerobic conditions significantly decreased the extent of the reaction with increased stirring rate. This impact was minimized by using a nitrogen environment or by limiting agitation during the reaction step.The methods developed were capable of removing up to 1000 µg/cm2 arsenic (of sodium arsenite) from simulated artifacts to levels near the lower detection limit of the X-ray Fluorescence Spectrometer (1 µg/cm2) without leaving detectable residues according to Attenuated Total-Reflection Fourier Transform Infrared Spectroscopy. Similar results were achieved in removing mercury (of mercuric chloride) from non-sulfur containing materials; however, the solutions and processes developed were not capable of removing mercury from sulfur-containing materials such as wool and feathers.
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Farrell-Poe, Kitt. "Arsenic in Private Water Wells." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2010. http://hdl.handle.net/10150/156928.
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3 pp.<br>1. Drinking Water Wells; 2. Private Water Well Components; 3. Do Deeper Wells Mean Better Water; 4. Maintaining Your Private Well Water System; 5. Private Well Protection; 6. Well Water Testing and Understanding the Results; 7. Obtaining a Water Sample for Bacterial Analysis; 8. Microorganisms in Private Water Wells; 9. Lead in Private Water Wells; 10. Nitrate in Private Water Wells; 11.Arsenic in Private Water Wells; 12. Matching Drinking Water Quality Problems to Treatment Methods; 13. Commonly Available Home Water Treatment Systems; 14. Hard Water: To Soften or Not to Soften; 15. Shock Chlorination of Private Water Wells<br>This fact sheet is one in a series of fifteen for private water well owners. The one- to four-page fact sheets will be assembled into a two-pocket folder entitled Private Well Owners Guide. The titles will also be a part of the Changing Rural Landscapes project whose goal is to educate exurban, small acreage residents. The authors have made every effort to align the fact sheets with the proposed Arizona Cooperative Extension booklet An Arizona Well Owners Guide to Water Sources, Quality, Testing, Treatment, and Well Maintenance by Artiola and Uhlman. The private well owner project was funded by both the University of Arizonas Water Sustainability Program-Technology and Research Initiative Fund and the USDA-CSREES Region 9 Water Quality Program.
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Uhlman, Kristine. "Arsenic in Arizona Ground Water -- Source and Transport Characteristics." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2008. http://hdl.handle.net/10150/146413.
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4 pp.<br>Following on the U.S. Environmental Protection Agency's "Arsenic Rule" decision to require public water systems to lower the allowable arsenic content in drinking water from 50 parts per billion (ppb) to 10 ppb by January 23, 2006, private well owners across the state have realized the importance of testing their own water supply for arsenic. Under Arizona law, it is the sole responsibility of the private well owner to determine the quality (potability) of their private well water. This article discusses the geologic prevelance of arsenic across the state, and options available to the well owner to address this water quality concern.
Expected to be the first in a 3-part series on ground water quality issues common in Arizona.
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Dhinsa, Harkirat S., University of Western Sydney, and School of Civic Engineering and Environment. "Atomic absorption spectroscopic determination of mercury, selenium and arsenic in biological and environmental materials." THESIS_XXXX_CEE_Dhinsa_H.xml, 1998. http://handle.uws.edu.au:8081/1959.7/254.
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This thesis carefully investigates some of the limitations of existing methods for atomic spectroscopic determination of mercury, selenium and arsenic in biological and environmental materials. In particular the need for adequate sample preparation to ensure reliable atomic spectroscopic determination of these metalloids was demonstrated extensively. The thesis evaluates four most commonly used wet digestion methods for the accurate determination of mercury in biological and environmental materials by cold vapour atomic absorption spectroscopy. Excellent recovery efficiencies were obtained with this digestion mixture in fish homogenate, horse kidney, soil, canned fish and hair samples for inorganic and organic mercury. The suitability of the digestion method for the reliable determination of mercury in soil, hair and canned fish samples was also demonstrated. Mercury levels in these samples were found within normal acceptable range. The thesis outlines a new simple procedure for overcoming the loss of mercury due to sample charring. It also described a new sample ultrasound low temperature wet digestion method for biological and environmental materials. The main advantage of this approach over other conventional methods is its ability to release all mercury in inorganic form from biological and environmental samples at much lower temperatures than reported earlier<br>Doctor of Philosophy (PhD)
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Yathavakilla, Santha Venkata. "Speciation of Selenium, Mercury and Arsenic in Food by Inductively Coupled Plasma Mass Spectrometry." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1179516979.
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Thorp, Steven Gregory. "Environmental Assessment of Arsenic and Mercury Levels at the Garfield Mill Site, Calico, California." CSUSB ScholarWorks, 2019. https://scholarworks.lib.csusb.edu/etd/922.
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Environmental impacts of mining at Calico, California, are poorly understood in comparison to the details of its history of silver production. Human health risks associated with arsenic from the lode rock, as well as mercury from the silver milling process, include central nervous system damage, organ failure, and death. To quantify the potential human health risk and manage remediation of this site, tailings from the Garfield Mill site were digitally mapped and chemically analyzed by portable x-ray fluorescence, which permitted volumetric estimates of total mill tailings and the arsenic and mercury budget, as well as identification of anomalies in the distribution of these elements within the tailings deposit. Final products include a high-resolution digital orthomosaic map showing the extent of the tailings deposit, giving contours of arsenic and mercury distribution and identifying areas of high concern for future remediation. The information gathered during this study will be of immense use to the city of Barstow, providing a basis for future public health studies and assessments of human health risks in the area.
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Blue, Lisa Y. "IMMOBILIZATION OF MERCURY AND ARSENIC THROUGH COVALENT THIOLATE BONDING FOR THE PURPOSE OF ENVIRONMENTAL REMEDIATION." UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_diss/785.
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Mercury and arsenic are widespread contaminants in aqueous environments throughout the world. The elements arise from multiple sources including mercury from coal-fired power plants and wells placed in natural geological deposits of arseniccontaining minerals. Both elements have significant negative health impacts on humans as they are cumulative toxins that bind to the sulfhydryl groups in proteins, disrupting many biological functions. There are currently no effective, economical techniques for removing either mercury or arsenic from aqueous sources. This thesis will demonstrate a superior removal method for both elements by formation of covalent bonds with the sulfur atoms in N,N’-Bis(2-mercaptoethyl)isophthalamide (commonly called “B9”). That B9 can precipitate both elements from water is unusual since aqueous mercury exists primarily as a metal(II) dication while aqueous arsenic exists as As(III) and As(V) oxyanions.
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Uhlman, Kristine, Channah Rock, and Janick Artiola. "Arizona Drinking Water Well Contaminants." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2009. http://hdl.handle.net/10150/156930.
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4 pp.<br>This short fact sheet is taken from "Arizona Well Owner's Guide to Water Supply" currently in print. We plan to complete part 2 of this fact sheet by the end of July, 2009. Please note that the text has already been incorporated into the eXtension Community of Practice web page - - I am the author for the COP/Drinking Water group text on chemistry of naturally occurring water contaminants.<br>Arizona well water is often contaminated with elevated concentrations of naturally occurring constituents that are a human health concern. This short fact sheet is the first in a two-part series about what naturally occurring contaminants may be found in your water supply well and includes a brief discussion on environmental pollutants that originate from land use activities. If you own a well in Arizona, you have the sole responsibility for checking to see if your drinking water is contaminated. Arizona state law does not require private well owners to test or treat their water for purity. The second part of this series outlines what to sample for and how to understand your analytical results.
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Xiao, Tangfu. "Environmental impact of thallium related to the mercury-thallium-gold mineralization in southwest Guizhou Province, China." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ65214.pdf.
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Leeves, Sara Ann. "Bioaccumulation of arsenic, cadmium, mercury, lead and selenium in the benthic and pelagic food chain of Lake Baikal." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for biologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-13438.
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Increased anthropogenic release of potentially toxic trace elements such as arsenic (As), cadmium (Cd), mercury (Hg), lead (Pb) and selenium (Se) into freshwater ecosystems over the past century has caused much concern. These elements are well known toxicants in aquatic ecosystems and may exert toxic effects even if present at relatively low concentrations in organisms. In this study, bioaccumulation of As, Cd, Hg, Pb and Se in the pelagic and benthic food chain of Lake Baikal have been investigated, with focus on the benthic and pelagic fish species. Concentrations of the selected trace elements have been analyzed in samples of water, plankton, benthic invertebrates and fish by High Resolution Inductively Coupled Plasma Mass Spectrometry (HR-ICP-MS). Concentration differences in the benthic and pelagic food chain of Lake Baikal have been investigated, with focus on benthic and pelagic fish species. In addition, spatial differences in the concentration of these potentially toxic elements between Selenga Shallows (possibly polluted site) and Listvyanka Bay (reference site) were included in the analysis to reveal potential anthropogenic impact on the lake.The comparative study revealed some concentration differences in water and biotic components at the two sampling locations. The concentration of Pb was significantly higher in water from the Selenga Shallows. However, several of the biota samples had highest concentrations of trace elements at Listvyanka Bay. This can be related to higher bioavailability of trace elements at Listvyanka Bay, possibly caused by lower abundance of natural ligands at this location. In both the pelagic and benthic food chain of Lake Baikal, Hg showed indication of biomagnification while As, Cd and Pb seemed to be biodiluted. When comparing fish inhabiting the pelagic and benthic food chain, differences in concentrations of As and Hg were identified. The As concentrations were twice as high in pelagic fish, while the benthic fish had seven times higher Hg content compared to pelagic fish. The observed concentration differences of As and Hg may be related to such as different complexity of the two food chains, different feeding strategies and habitat. Based on the tissue Se:Hg molar ratio there is no risk of Hg induced toxicity in the endemic fish species of Lake Baikal at the present. In general, the present study confirms low concentrations of potentially toxic chemical elements (As, Cd, Hg, Pb and Se) in Lake Baikal in comparison to other freshwater ecosystems.
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Gregg, Anne Marie. "Arsenic in drinking water the public health implications of monitoring technologies /." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1195673218.
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Artiola, Janick F., and Sarah T. Wilkinson. "How to Lower the Levels of Arsenic in Well Water: What Choices do Arizona Consumers Have?" College of Agriculture, University of Arizona (Tucson, AZ), 2015. http://hdl.handle.net/10150/347243.
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10 pp.<br>Arsenic levels are often above drinking water standards in Arizona groundwater, at levels that may affect health. Private well owners are responsible for testing and treating they own water. This publication gives an overview of arsenic well water and discusses home water treatment options, including detailed descriptions of distillation, reverse osmosis, and iron filters to lower arsenic and other common water constituents in drinking water.
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ALAMILLO, LOPEZ VERONICA MARGARITA 555335, and LOPEZ VERONICA MARGARITA ALAMILLO. "Compositos de cascarón de huevo / nanoparticulas de óxido de hierro - plata metálica, y su funcionalidad en la eliminación de iones pb, as y hg, en medio acuoso." Tesis de doctorado, Universidad Autónoma del Estado de México, 2018. http://hdl.handle.net/20.500.11799/95026.
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Abstract The synthesis of nanoparticles of metallic silver and hematite supported on calcite by microwaves, forms a mesoporous material with an average diameter of 17.97 nm and a surface area of 1.4 m2 / g, the silver nanoparticles are hemispherical with a size between 10 and 20 nm in diameter and hematite nanoparticles less than 5nm. This material has a synergistic effect when placing 10mg of the composition in aqueous solution containing 10mg / L of lead, arsenic and mercury; these are eliminated 100%. The process of adsorption of the metals in the composition is adjusted to the kinetic model of pseudosecond order, with two active sites of adsorption.
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Annaduzzaman, Md. "Effectiveness of Tubewell platform color as screening tool for arsenic and manganese in drinking water wells: An assessment from Matlab region Southeastern Bangladesh." Thesis, KTH, Mark- och vattenteknik (flyttat 20130630), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-124582.
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Arsenic (As) contamination in groundwater is a severe and adverse water quality issue for drinking purposes, particularly in Southeast Asia, where groundwater is the main drinking water source. Bangladesh is one of the countries where arsenic poisoning in groundwater is massive and it is essential to find out a reliable alternative safe drinking water source. In this process, it is very much needed to identify As-rich wells to avoid drinking water from them and to assess the extent of contamination as well. This study attempts to evaluate the potentiality of tube-well (TW) platform color as low-cost quick screening tool for As and Mn as well in drinking water wells (n=272). The result shows strong association of red color platform with As-rich water in the corresponding wells compared to WHO guideline value of 10 μg/L (98.7% certainty) and regional (Bangladesh/India) standard of 50 μg/L (98.3% certainty). The sensitivity and efficiency of red color platforms to screen high As water in TW for 10 μg/L are 98% and 97%. Similarly, for 50 μg/L, it is 98% for both sensitivity and efficiency. However, because of a very low number (n=4) of TW platform stained with black color, it is not possible to make any conclusion on the potentiality of black color as a screening tool for Mn. This study suggests that red colored platform can be potentially used for primary identification of TWs with elevated As concentration and to prioritise sustainable As mitigation management. However, this study does not discard the concept of black colored platform as a screening tool for Mn-rich water. Further study is recommended to evaluate the efficiency of black color as a screening tool for Mn.
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Afton, Scott E. "The development of varying methodologies to speciate and monitor the interactions of selenium and environmental contaminants in plants." Cincinnati, Ohio : University of Cincinnati, 2008. http://rave.ohiolink.edu/etdc/view.cgi?acc_num=ucin1227296686.
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Thesis (Ph. D.)--University of Cincinnati, 2008.<br>Advisor: Joseph Caruso (Committee Chair), William Heineman (Committee Member), Bruce Ault (Committee Member). Title from electronic thesis title page (viewed Jan. 18, 2009). Keywords: selenium; arsenic; mercury; sulfur; xenon; ESI-ITMS; HPLC; ICPMS; XAFS; Plants; Phytoremediation. Includes abstract. Includes bibliographical references.
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Houben, Adam James. "Effect of Shoreline Subsidence and Anthropogenic Activity on Northwest Territories’ Lakes." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/35679.
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Thawing permafrost – in the form of shoreline retrogressive thaw slump events – influence adjacent arctic tundra lake systems near Inuvik, NT. Slump-affected lakes demonstrated lower organic matter and key nutrients such as phosphorus (P), as well as greater water clarity. Key terrestrial permafrost soil indicators such as U, Sr, and Li, were identified to be elevated in slump-affected lakes, while other more biologically important metals (e.g. Fe, Mn) were significantly lower in affected lakes. These physical-chemical changes led to increasing P-limitation for both phytoplankton and periphyton, resulting in lower phytoplankton biomass (Chl-a). Using P as covariate in ANCOVA analysis, slump-affected lakes were also lower in phytoplankton biomass (Chl-a) relative to other study landscapes across the Canadian low-Arctic.
Slump-affected lakes also exhibited lower organic matter leading to lower overall Hg concentrations within slump-affected lakes. However, this same reduction in dissolved organic carbon (DOC) has also led to an increase in bioavailable Hg, and increased bioaccumulation of Hg in both periphyton as well as macroinvertebrate species in our most disturbed lakes with DOC concentrations less than 6 and 9 mg DOC/L, respectively. A negative correlation between Hg bioaccumulation and DOC above these concentrations was also observed, and is the typical condition within reference lakes.
The legacy impacts of mining were also observed in lakes within 25 km of the Giant Mine roaster stack in the Yellowknife region. Increases in both arsenic (As) and methyl mercury were measured in lakes nearer to the mine, with As concentrations well above water quality guidelines in lakes within 17 km of the roaster stack. This research highlights the necessity of baseline environmental monitoring prior to resource development, as well as the potential for compounded influences of such development within sensitive permafrost regions exposed to thawing.
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Nascimento, Fernando Henrique do. "Desenvolvimento de métodos de análise por injeção sequencial com detecção eletroquímica para a aplicação em estudos de interação de Hg(II), As(III) e Se(IV) com ligantes heterogêneos de ocorrência natural." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-30112016-100019/.
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Os diferentes efeitos que Hg(II), As(III) e Se(IV) causam ao meio ambiente e à saúde dos seres vivos levaram ao desenvolvimento de uma ampla variedade de técnicas analíticas para a determinação destas espécies, com destaque para a voltametria e cronopotenciometria de redissolução. As interações com ligantes heterogêneos de ocorrência natural são fundamentais para o transporte e disponibilidade de Hg(II), As(III) e Se(IV) no meio ambiente. O estudo das interações pode contribuir com tecnologias de remediação mais eficientes, evitando a introdução, ou permitindo a remoção de espécies de Hg(II), As(III) e Se(IV) de meios impactados. Na presente tese foram desenvolvidos métodos controlados por Análise por Injeção Sequencial (SIA) com detecção eletroquímica, especificamente voltametria de onda quadrada (SIA-SWASV) para Hg(II), As(III) e Se(IV) e um método com detecção por cronopotenciometria (SIA-SCP) para Hg(II) visando sua utilização em estudos de interação com vermiculita natural e modificada com tióis, microalga Chlamydomonas reinhardtii e vermiculita modificada com poli-hidróxi-cátions de Fe(III). Em todos os casos foram usados eletrodos de ouro como eletrodo de trabalho. Os limites de detecção (LD) para Hg(II) foram de 0,01 e 0,02 µmol L-1 para os métodos SIA-CSP e SIA-SWASV, respectivamente. Para As(III) e Se(IV) os valores de LD foram de 0,02 e 0,06 µmol L-1, respectivamente. Para a adsorção de Hg(II) em amostras de vermiculita, a amostra modificada com cisteamina foi a que apresentou maior capacidade de adsorção (qmax), 83±30 µmol g-1. A variação da força iônica e do pH não afetou significativamente a adsorção nos materiais modificados com cisteamina, cisteína e (3-mercaptopropil)trimetoxisilano, devido a alta afinidade entre Hg(II) e os grupos tióis. Dessorções em HCl foram sempre < 21%, sugerindo que todos os materiais possuem potencialidade para aplicação in situ em ambientes impactados. A adsorção de Se(IV) na FeOH-VT resultou um qmax = 45±4 µmol g-1, sendo que a capacidade diminui com o aumento da força iônica, indicando que a atração eletrostática exerce papel importante na adsorção. A biossorção de Hg(II) na C. reinhardtii teve seu maior valor de qmax, 3,3±0,8 mmol g-1, em pH 4,0, sendo o Hg(II) concentrado no interior das células. A capacidade de adsorção de Hg(II) em C. reinhardtii foi significativamente maior do que na vermiculita, natural e modificada, sugerindo a elevada potencialidade para biorremediação de águas contaminadas. As medidas cronopotenciométricas feitas na presença das células sugerem que a interação é parcialmente lábil, de modo que essa fração trocável com o ambiente deveria ser considerada nos processos de tratamento. O aumento da força iônica praticamente não afetou a biossorção, indicando pouca influência de atração eletrostática. Estudos preliminares de biossorção de As(III) por C. reinhardii em um tempo de contato de 120 min resultaram em qmax = 41±1 µmol g-1, independente da variação do pH entre 4 e 7, enquanto que o aumento da força iônica aumentou as quantidades de As(III) biossorvido.<br>The different effects that Hg(II), As(III) and Se IV) cause to the environment and to the health of living beings led to the development of a wide range of analytical techniques for the determination of these species, especially stripping voltammetry and chronopotenciometry. Interactions with heterogeneous naturally occurring ligands play a key role in the transport and availability of Hg(II), As(III) and Se(IV) in the environment. The study of these interactions may contribute to more effective remediation technologies, avoiding their loading in environmental compartments, or enabling the removal of Hg(II), As(III) and Se(IV) species from impacted medium. The present thesis describes the development of methods controlled by Sequential Injection Analysis (SIA) with electrochemical detection, specifically square wave voltammetry (SIA-SWASV) for determination of Hg(II), As(III) and Se(IV), and chronopotentiometry (SIA-SCP) for Hg(II) aiming their use in interaction studies with the clay mineral vermiculite (natural and modified with thiols and polyhydroxy cations of Fe(III)) and with the microalgae Chlamydomonas reinhardtii. In all cases gold electrodes were used as working electrode. The limits of detection (LOD) for Hg(II) were 0.01 and 0.02 µmol L-1 for SIA-SCP and SIA-SWASV methods, respectively. For As(III) and Se(IV) the LOD values were 0.02 and 0.06 µmol L-1, respectively. For the adsorption of Hg(II) in vermiculite samples, the sample modified with cysteamine showed the highest adsorption capacity (qmax), 83 ± 30 µmol g-1. As a consequence of the high affinity between Hg(II) and the thiols, the variation of the ionic strength and pH did not significantly affect the adsorption on materials modified with cysteamine, cysteine, and (3-mercaptopropyl) trimethoxysilane. Desorption in HCl was always < 21%, suggesting that all materials have potential for in situ application in impacted environments. Adsorption of Se(IV) in FeOH-VT resulted in a qmax = 45 ± 4 µmol g-1, and the capacity decreased with increasing ionic strength, indicating that the electrostatic attraction played an important role in adsorption. The biosorption of Hg(II) by C. reinhardtii had its greatest value qmax, 3.3 ± 0.8 mmol g-1, at pH 4.0, and Hg(II) concentrated in the cells. The adsorption capacity of Hg(II) in C. reinhardtii was significantly higher than that in vermiculite, natural or modified, suggesting high potential for bioremediation of contaminated water. The chronopotentiometric measurements in the presence of cells suggested that the interaction was partially labile, so that the exchangeable fraction with the environment should be considered for treatment processes. The increase in ionic strength did not affect the biosorption, indicating little influence of electrostatic attraction. Preliminary studies on biosorption of As(III) by C. reinhardii with a contact time of 120 min resulted in qmax = 41 ± 1 µmol g-1, independent of pH variation between 4 and 7, whereas the increase of ionic strength increased amounts of As(III) biosorbed.
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Blay, Claire. "Characterisation of intermixed quantum well material by measurements of spontaneous emission." Thesis, University of Bath, 2000. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323571.
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Stupar, Yohana Vanesa. "Trends and rates of mercury and arsenic in sediments accumulated in the last 80 years in the climatic-sensitive Mar Chiquita system, Central Argentina." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00920306.
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In South America and especially in Argentina, the behaviour of mercury (Hg) and arsenic (As) mainly in sediments remains poorly understood. The Mar Chiquita system and more particularly the Laguna del Plata with its associated Suquía River basin is used here as a case study to identify the dynamic of these two trace elements. Their distribution in space and time are studied in relation with the anthropic presence and the hydrological conditions that importantly changed in the last century.The methodology consisted first to study the spatial distribution of mercury and arsenic thanks to the analysis of water and sediments taken all along the Suquía River and Laguna del Plata. Secondly, the sampling and study of a sediment core taken in Laguna del Plata allowed to evaluate variations of Hg and As with time.The implementation of selective extractions allowed to better identify Hg and As bearing phases. The global interpretation of the results and the support of satellites images revealed the important role played by climate changes and hydrological variations in the control of mercury and arsenic behaviour within the Mar Chiquita system. The combination of these different approaches revealed that the dynamic of mercury and arsenic shows contrast behaviour. Hg concentrations are low when the climate conditions are dry and lake-level is low. They are mainly associated to sulphurs carried by the Suquía River. The augmentation in regional precipitations produced higher runoff, rise in the lake-level and an increment in Hg accumulations. In this period Hg is mainly associated to the organic matter. As instead is contributed to the lake in solution and by the influence of winds from the loessic Chaco Pampean Plain in drier periods. As is associated to reactive Fe and Mn oxyhydroxides throughout the core. High concentrations in the bottom of the core are also associated to sulphides while in the middle and upper part As concentrations are as well associated with carbonates.
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Beckers, Felix [Verfasser]. "Mobilization, Methylation, and Ethylation of Mercury in Contaminated Floodplain Soils under Controlled Laboratory Redox Conditions as Influenced by Potential Immobilizing Agents as well as Mobilization of Mercury under Field Conditions / Felix Beckers." Wuppertal : Universitätsbibliothek Wuppertal, 2019. http://d-nb.info/1206122870/34.
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Asselin, Julie. "Design of a flow-through extraction cell for rapid determination of toxic metals (arsenic, cadmium, chromium, copper, mercury, lead, tin, zinc) from soils and sediments." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=115838.
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The goal of this study was to design, characterize and test a flow-through extraction cell for rapid determination of toxic metals present in soil and sediment samples.<br>Based on a design elaborated by Jean Bouffard, a Teflon cell was first machined, but it appeared to be leaky and hard to disassemble without breaking the fritted glass discs. To overcome these difficulties, a poly ether ether ketone (PEEK) cell was machined and several parts were modified. Even though the shape and seal of the components seemed to be affected when heated, the cell was working at room temperature and proved promising for future work.<br>Finally, the EPA (Environmental Protection Agency) method 1311 was applied on some real samples, and the extracts were analyzed in order to get reference results that could eventually be compared to results given by extracts obtained with the flow-through cell.*<br>*This dissertation is a compound document (contains both a paper copy and a CD as part of the dissertation). The CD requires the following system requirements: Microsoft Office.
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Taerakul, Panuwat. "Characterization of trace elements in dry flue gas desulfurization (FGD) by-products." Connect to this title online, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1119038889.
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Thesis (Ph. D.)--Ohio State University, 2005.<br>Title from first page of PDF file. Document formatted into pages; contains xvii, 173 p.; also includes graphics Includes bibliographical references (p. 161-173). Available online via OhioLINK's ETD Center
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Robson, Thomas. "Weathering of sulfide ores in model soils, potentially toxic element release and bioavailability." Thesis, University of Plymouth, 2013. http://hdl.handle.net/10026.1/2859.
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The exploitation of metallic sulfide ores produces vast quantities of fine-grained wastes hosting potentially toxic elements (PTEs). There are concerns that, if improperly disposed of and managed, waste mineral particles can behave as vectors that disperse PTEs via aeolian and fluvial transport, subsequently contaminating soils and crops used to support human populations. The importance of these particles, as sources and influencers of PTE biogeochemistry in productive soils, has received limited research. Long-term (365 d) batch incubation experiments, field weathering experiments and phytoavailability trials, were performed to establish the rate, patterns and factors limiting PTE (Cd, As, Hg) release from grains of sphalerite (Zn(Fe,Cd)S), arsenopyrite (FeAsS) and cinnabar (HgS) into soil matrices (0.1 % mineral:soil m/m), and the bioavailability of the liberated PTEs to important food crops (Tricitum aestivum, wheat and Oryza sativa, rice). All three of the ores underwent chemical weathering in oxic agricultural soils of both temperate and sub-tropical provenance, during which nonessential PTEs (cadmium, mercury, arsenic) were released in bioavailable forms, at rates relevant to agricultural production. Sphalerite weathered at a rate of 0.6 to 1.2 % a-1 (Cd basis) in the experimental soils, releasing 0.5 to 1 μmol Cd g-1 ZnS a-1 into the soil matrix. Cinnabar weathering reached a maximum of 12.0 – 13.5 % (Hg basis) after 90 days exposure in oxic soils, whereas arsenopyrite weathering was rapid and extensive, reaching 56 to 66 % (S basis) after 180 days. The PTE concentrations accumulated in edible grains of wheat and rice grown in the sulfide-contaminated soils were higher than international food safety limits by factors of 8 (Cd in rice), 10 – 30 (Hg in wheat and rice) and 8 – 12 (As in wheat and rice). The primary geochemical factors controlling PTE release and bioavailability were solid-phase associations (i.e. PTEs complexed by clays, metal oxyhydroxides and organic matter) and the precipitation of secondary mineral phases. Weathering arsenopyrite grains were passivated from further oxidation by secondary iron-arsenate phases, which also co-precipitated arsenic liberated from the ore. Secondary phase formation was identified as the cause of decreasing extractable Hg (liberated from cinnabar) after mercury release from cinnabar peaked (≤ 90 days exposure). For sphalerite, the evidence indicates that secondary sulfide phases formed under flooded (sulfate-reducing) soil conditions (paddy rice), limited the bioavailability of cadmium previously liberated under oxic conditions. These key findings demonstrate a potential human health hazard relating to the dispersal of PTE-hosting sulfide ore particles produced by mining activities into soils supporting human populations via crop contamination. This work also highlights differences in ore geochemistry, showing the need for additional research on different ore minerals and their alteration products.
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Sohel, Nazmul. "Epidemiological and Spatial Association between Arsenic Exposure via Drinking Water and Morbidity and Mortality population based studies in rural Bangladesh /." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Universitetsbiblioteket [distributör], 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-121788.
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Parada, Carolina Angélica da Silva. "Construção e caracterização de linhagens bacterianas Gram-negativas recombinantes com capacidade aumentada para biorremediar efluentes contaminados com mercúrio e arsênio." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/87/87131/tde-01062012-085721/.
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Este trabalho descreve a construção de plasmídeos para expressão e ancoragem de proteínas de alta afinidade a íons Hg2+ e As5+. Os genes merR e arsR de C. metallidurans foram inseridos no vetor que contém o sistema para expressão e ancoragem de proteínas heterólogas em bactérias Gram-negativas originando os plasmídeos pCM-Hg e pCM-As. MerR e ArsR foram produzidas sob comando do promotor pan. E. coli recombinantes apresentaram resistência 100% superior a Hg2+ e As5+. C. metallidurans/pCM-As apresentou MIC > Na3As02 1000 mM sendo a Gram-negativa com maior capacidade de sobrevivência a íons As5+. Os plasmídeos elevaram a sobrevivência das bactérias estudadas, podendo ser usados para aumentar índices de sobrevivência e fornecer viabilidade a outras cepas. Células recombinantes apresentaram capacidade de adsorver Hg2+ ou As5+ do meio em níveis superiores às linhagens selvagens. As bactérias descritas são excelentes candidatas para biorremediação. Este trabalho apresenta pela primeira vez a ancoragem da proteína ArsR na superfície celular de um micro-organismo.<br>This work describes the construction of plasmids for expression and anchoring of high affinity proteins to Hg2+ or As5+ ions. C. metallidurans merR and arsR genes were inserted into the vector which contains the system for expression and anchoring of heterologous proteins in Gram-negative bacterias origining the plasmids pCM-Hg and pCM-As. MerR and ArsR were produced under pan promoter command. Recombinant E. coli showed resistance 100% higher to Hg2+ and As5+. C. metallidurans/pCM-As showed MIC > Na3As02 1000 mM being the most resistance Gram-negative able to survive in As5+ sites. The plasmids increased the studied Gram-negatives bacterial surviving and they can be utilized in other strains to increase the surviving levels and supply viability. Recombinant cells showed ability for adsorption of Hg2+ or As5+ from the media in enhanced levels as compared to the wild type. The described bacterias are excellent candidates for bioremediation. This work presents for the first time the cell surface display of ArsR protein on a microorganism.
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Takeda, Simone Harue Kimura. "Exposição da população adulta da RMSP a contaminantes ambientais: associação entre o conteúdo corpóreo de metais e fatores de risco." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/5/5137/tde-06082015-142625/.
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A exposição humana a contaminantes ambientais é uma preocupação mundial. Nesse contexto, nas últimas décadas, avanços metodológicos têm proporcionado fortes bases quantitativas para a estimativa dos riscos à saúde humana associada a exposições a contaminantes ambientais. A biomonitorização humana é de grande utilidade para estabelecer a distribuição da exposição na população geral, identificar grupos vulneráveis e populações com exposição mais elevada. Os objetivos deste estudo foram avaliar os níveis de exposição da população adulta da região metropolitana de São Paulo (RMSP) aos metais As, Cd, Hg, Pb, Cu e Mn e verificar os possíveis fatores relacionados à exposição. Amostras de sangue e cabelo de doadores de sangue residentes na RMSP há pelo menos um ano foram coletadas em 2009. Os resultados deste estudo indicam que, no geral, a população estudada não está exposta a níveis preocupantes desses metais. As médias geométricas para As, Cd, Pb, Hg, Cu e Mn em sangue foram 3,6 ug/L, 0,12 ug/L, 23,9 ug/L, 1,4 ug/L, 999,4 ug/L e 12,5 ug/L, respectivamente. Em cabelo, as médias geométricas foram 0,02 ug/g, 0,03 ug/g, 0,54 ug/g, 0,13 ug/g, 12,44 ug/g e 0,32 ug/g para As, Cd, Pb, Hg, Cu e Mn, respectivamente. Em sangue, a concentração de As foi associada a nível de educação e o consumo de frango; o nível de Cd foi influenciado pelo hábito de fumar, ramo de atividade e ter residido em área agrícola; a concentração de Pb foi influenciado pelo gênero, idade, nível de educação, uso de medicamentos, consumo de frutos do mar e trabalho pregresso com agrotóxicos; os determinantes de Hg foram consumo de peixe, nível de educação e idade; os níveis de Cu foram influenciados pelo gênero, uso de medicamentos e reforma recente da casa; e a concentração de Mn foi influenciada pela reforma recente da casa, ter residido em área agrícola e trabalho pregresso com agrotóxicos. Em cabelo, os níveis de As foram influenciados pelo gênero, tratamento capilar, frequência de consumo de peixe e raça; o determinante de Cd em cabelo foi o gênero; para o Pb, os determinantes foram gênero e renda familiar; os níveis de Hg foram influenciados pelo gênero, idade, frequência de consumo de peixe, frutos do mar e produtos de origem animal, consumo de bebida alcoólica além de trabalho e raça; os níveis de Cu foram influenciados pelo gênero e o consumo de bebida alcoólica; os fatores associados aos níveis de Mn foram gênero, raça, rua pavimentada e origem da água de beber. Os níveis de Hg, Cd, Cu e Pb em sangue apresentam fraca correlação com os níveis em cabelo<br>Human exposure to environmental contaminants is a global concern. In this context, in recent decades, methodological advances have provided strong quantitative basis for estimating the risks to human health associated with exposure to environmental contaminants. Human biomonitoring is useful to establish the distribution of exposure in the general population, identify vulnerable groups and populations with higher exposure. The aims of this study were to evaluate the exposure levels of adult population from metropolitan area of São Paulo (MRSP) to metals As, Cd, Hg, Pb, Cu and Mn and verify the related factors to exposure. Blood and hair samples from blood donors living in MASP for at least one year were collected in 2009. The results of this study indicate that, overall, the study population is not exposed to HIGH levels of these metals. Geometric means to As, Cd, Pb, Hg, Cu and Mn in the blood were 3.6 ug/L, 0.12 ug/L, 23.9 ug/L, 1.4 ug/L, 999.4 ug/L and 12.5 ug/L, respectively. Regarding in hair, geometric means were 0.02 ug/g, 0.03 ug/g, 0.54 ug/g, 0.13 ug/g, 12.44 ug/g, 0.32 ug/g for, As, Cd, Pb, Hg, Cu and Mn respectively. In blood, As concentration was affected by education level and poultry consumption; Cd level was affected by smoking status, occupation and lived in rural area in the past; Pb concentration was affected by gender, age, education level, medicine intake, seafood consumption and work with pesticides in the past; Hg determinants were fish consumption, education level and age; Cu levels were affected by gender, medicine intake and refurbished house; and the concentration of Mn was affected by refurbished house, lived in rural area and work with pesticides in the past. Regarding in hair, As levels are affected by gender, hair treatment, frequency of fish consumption and race. The determinant of Cd in hair was gender; for Pb, the determinants were gender and family income; Hg levels were affected by gender, age, frequency of fish consumption, seafood and animal products, alcohol consumption in addition to current work and race; Cu levels were affected by gender and alcohol consumption; related factors to Mn levels were gender, race, paved street and source of drinking water. Hg levels, Cd, Cu and Pb in blood are weakly correlated with levels in hair
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Perez, Caroline. "Estudo sobre a determinação de elementos tóxicos (As,Cu e Hg) em amostras de biomonitores da poluição atmosférica pelo método de análise por ativação com nêutrons." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-23072018-092731/.
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No biomonitoramento da poluição atmosférica, as determinações de elementos tóxicos têm sido de suma importância para identificação das suas fontes de emissão e dos efeitos ocasionados com a sua exposição. Consequentemente diferentes técnicas analíticas vêm sendo aprimoradas e aplicadas para essa finalidade, entre elas, a análise por ativação com nêutrons (NAA). Essa técnica apresenta vantagens para a quantificação de elementos poluentes, devido a sua capacidade de análise multielementar e a sua alta sensibilidade, precisão e exatidão dos resultados. Entretanto, nos trabalhos de biomonitoramento, a NAA não tem sido muito utilizada na determinação dos elementos tóxicos As, Cu e Hg. O objetivo deste trabalho foi estabelecer um procedimento adequado de NAA para a determinação de As, Cu e Hg em amostras de biomonitores da poluição atmosférica (liquens, bromélias e cascas de árvores). O procedimento de NAA consistiu em irradiação sob fluxo de nêutrons térmicos alíquotas de amostras juntamente aos padrões sintéticos dos elementos, seguida de espectrometria de raios gama. Foram realizados ensaios preliminares de NAA para definição das condições de irradiação e de medição para determinação desses três elementos e, para isso, foram analisados diversos materiais de referência certificados (MRCs). Os resultados de As, Cu e Hg nos MRCs demonstraram boa exatidão e precisão (HORRAT < 2 e IZscoreI < 2). Isto é, para determinação de As, foi verificado que irradiações de 1 h e tempo de decaimento de 1 d para as medições permitem obter resultados satisfatórios. O As foi encontrado em todas as espécies de biomonitores analisadas e os valores de limites de detecção foram inferiores às suas frações mássicas, demostrando que o procedimento proposto pode ser satisfatoriamente utilizado nas análises de biomonitores. Nas determinações de Cu nos MRCs, foi observado que esse elemento pode ser quantificado por meio das irradiações de 20 s e de 1 h pelas medições de 66Cu e de 64Cu, respectivamente. Entretanto, dependendo da amostra, nas irradiações de 1 h pode ocorrer a interferência da alta atividade do 24Na. Nas análises de biomonitores, os tempos de irradiação de 1 h e de decaimento de 1 d foram mais apropriados que as irradiações de curta duração de 20 s, uma vez que os dados obtidos apresentaram boa precisão e limites de detecção mais baixos que os das irradiações de 20 s. Para determinação de Hg, verificou se que não há perda desse elemento nas irradiações realizadas em invólucros ou cápsulas de polietileno. O invólucro foi escolhido devido ao seu baixo custo e a facilidade de aquisição. O tempo de irradiação de 1 h foi apropriado para evitar os problemas das interferências espectrais do 198Au e 75Se, que foram mais evidentes para 8 h de irradiação. O Hg não foi detectado em nenhum dos biomonitores analisados e os limites de detecção calculados variaram de 0,01 a 6,8 μg g-1. Pelos resultados obtidos neste trabalho, concluiu-se que o procedimento de NAA estabelecido pode ser aplicado no biomonitoramento de As, Cu e Hg da poluição aérea e cabe ainda ressaltar que esses três elementos podem ser determinados por meio de uma única irradiação de 1 h, dependendo dos teores destes elementos nas amostras.<br>In the atmospheric pollution biomonitoring, the determination of toxic elements has been of major importance to the identification of their emission sources and of the caused effects by their exposure. Consequently, different analytical techniques have been improved and applied for this purpose, among them, the neutron activation analysis (NAA). This technique presents advantages for the quantification of pollutant elements due to its capability of multielemental analyses and its high sensitivity, precision and accuracy of results. However, in biomonitoring works, NAA has not been widely used in the determination of toxic elements As, Cu and Hg. The aim of this study was to establish adequate procedures of NAA for As, Cu and Hg determination in biomonitors of atmospheric pollution (lichens, bromeliads and tree barks). The NAA procedure consisted of irradiation, under thermal neutron flux, aliquots of samples with the elemental synthetic standards, followed by gamma ray spectrometry. Preliminary assays of NAA were carried out to define the irradiation and measurement conditions for these three elements determinations. For this purpose, several certified reference materials (CRMs) were analyzed. Results of As, Cu and Hg obtained in CRMs demonstrated good precision and accuracy of obtained data (HORRAT < 2 and IZ scoreI < 2). For As determination, irradiation time of 1 h and 1 d of decay time for the measurements allowed to obtain satisfactory results. Arsenic was detected in all analyzed samples of biomonitors and the detection limits were lower than its mass fractions, showing that the proposed procedure can be satisfactorily used in the biomonitor analyses. In Cu determination in CRMs, it was verified that this element could be quantified using irradiations of 20 s and of 1 h and by measuring 66Cu and 64Cu, respectively. However, depending on the sample, the interference of high activity of 24Na may occur. In the analyses of biomonitors, irradiation time of 1 h and decay time of 1 d were more appropriate to obtain precise results than the short-term irradiations of 20 s. For Hg determination, loss of this element from polyethylene capsules or involucres was not observed and the involucres were selected due to its low cost and easy acquisition. Irradiation time of 1 h was chosen to avoid the problems of spectral interferences of 198Au and 75Se, which were more evident for 8 h of irradiation. Mercury was not detected in the analyzed biomonitor samples and the detection limits varied from 0.01 to 6.8 μg g-1. Based on the obtained results, it was concluded that the established NAA procedure can be applied in the biomonitoring of As, Cu and Hg of atmospheric pollution, and it should be noted that these three elements could be determined by a single irradiation of 1 h depending on the mass fractions of the elements in the samples.
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Haywood, Danette. "Survey of Health Effects among Residents Adjacent to a National Priority List Site in Ssouthwest Virginia." Digital Commons @ East Tennessee State University, 2003. https://dc.etsu.edu/etd/852.
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The Saltville Waste Disposal Site is a National Priority List site used during the 77- year operation (1895–1972) of an electrolytic chlorine and caustic soda plant. A cross-sectional study was conducted to determine disease prevalence among Saltville Medical Center (SMC) patients. Diseases associated with chronic exposures to mercury, arsenic, and lead were reviewed in patient records and these data were analyzed. Ratios of illness observed at the SMC were compared to health studies of similar environmental exposures and disease prevalence among residents of neighboring communities. Prevalence ratios were calculated for residents and non-residents of Saltville who were SMC patients. Saltville residence accounted for a higher risk of developing the targeted diseases (odds ratio=1.68, 95% confidence interval (1.54, 1.82)). Increased risk was among patients aged 31-45 years; with a history of smoking; and family history of the same disease.
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Richter, Larissa. "Especiação química e composição isotópica de elementos traço no ambiente : arsênio no pantanal e mercúrio na floresta amazônica." Thesis, Pau, 2020. http://www.theses.fr/2020PAUU3036.
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L'arsenic (As) et le mercure (Hg) sont des éléments toxiques et leur présence dans l'environnement peut avoir une origine naturelle et / ou anthropique. Dans les deux cas, la toxicité et la dynamique dans l'environnement dépendent fortement de la forme/espèce chimique dans laquelle se trouve l’élèment. Dans le Pantanal, des études antérieures ont révélé des concentrations élevées d'As dans les lagunes alcalines-salines et de faibles concentrations dans les eaux douces. Afin d'étudier les différences entre les lagunes, l'origine et la spéciation de l'As, des échantillons d'eau, de sédiments et de sols ont été collectés dans différentes lagunes et à différentes périodes. Les concentrations de As ont été déterminées par ICP-MS et la spéciation chimique (SC) analisée par LC-ICP-MS. Il a été observé que l'espèce prédominante était l’As(V) dont l’origine a été attribuée à trois facteurs: 1) le régime des inondations du Pantanal combiné à des forts taux d'évaporation; 2) le pH élevé des eaux des lagunes et 3) la présence de concentrations élevées de Fe, Al et de matière organique. Dans la forêt amazonienne, des émissions de Hg élevées sont observées en raison des feux de forêts. Cependant, aucune étude n'a évalué les changements qu'ils provoquent dans la spéciation chimique ou dans la composition isotopique du Hg (CI). Pour combler cette lacune, des expériences de feux programmés ont été menées sur deux parcelles de forêts en Amazonie brésilienne, où des échantillons de litière, de sols et de cendres ont été collectés. La CI a été analysée par MC-ICP-MS et la SC par GC-ICP-MS. Les résultats de la CI ont indiqué que pendant les incendies, le Hg n'est pas fortement fractionné isotopiquement. Ainsi, il a été estimé que les émissions de Hg ont une signature isotopique qui correspond à un mélange de signatures de litière et de sol. Pour la SC, il a été observé que les feuilles captent le méthylmercure atmosphérique (MMHg) et le déposent dans le sol, qui l'accumule avec le temps. Après le brûlage, le MMHg de la litière peut être principalement perdu tandis que celui présent dans le sol peut n’être perdu que partiellement<br>Arsenic (As) and Mercury (Hg) are toxic elements which presence in the environment may be attributed to natural or anthropic sources. In both cases, the toxicity and the dynamics in the environment are strongly dependent of the elements form/chemical specie. At the Pantanal, previous studies found high As concentrations in alkaline-saline lakes and low concentrations in fresh water lakes. Aiming to investigate the difference between these lakes, As origin and chemical speciation (CS), samples of water, sediments and soils were collected in distinct lakes and in different periods. As content was quantified by ICP-MS and its CS was analyzed by LC-ICP-MS. Results shown that As(V) was the main specie in this environment, which origin was attributed to three main factors: 1) the flood system combined with the high evaporation rates; 2) the high pH of the lakes and 3) the presence of high concentrations of Fe, Al and organic matter. On the other hand, in the Amazon rainforest, high rates of Hg emissions are observed due to forest burning. Nonetheless, no work in the literature has investigated what changes forest burning causes in Hg’s CS nor in its isotopic composition (IC). To fill this gap, prescribed burning experiments were performed in two different localities of the Brazilian Amazon rainforest, where samples of litter, soils and ashes were collected. IC was investigated by MC-ICP-MS and CS by GC-ICP-MS. IC results showed that during forest burning Hg isotopes did not fractionate sharply. Thus, Hg emissions to the atmosphere have an isotopic signature that correspond to a mixture of litter and soils’ isotopic signatures. For CS, it had been shown that forest leaves capture atmospheric methylmercury (MMHg), transferring it to the litter and consequently, to the soils, which cumulate this contaminant along the time. After burning, MMHg from litter can be lost completely whilst soils MMHg can be partially lost<br>O arsênio (As) e o mercúrio (Hg) são elementos tóxicos cuja presença no ambiente pode ter origem natural e/ou antrópica. Em ambos casos tanto a toxicidade quanto a dinâmica no ambiente são fortemente dependentes da forma/espécie química na qual se encontra o elemento. No Pantanal, estudos anteriores encontraram altas concentrações de As em lagoas alcalino-salinas e baixas concentrações em águas doces. Visando investigar as diferenças entre as lagoas, a origem e a especiação do As, coletaram-se amostras de águas, sedimentos e solos em lagoas distintas e em diferentes períodos. Os teores de As foram determinadas por ICP-MS e a especiação química (EQ) foi analisada por LC-ICP-MS. Observou-se que a espécie predominante foi o As(V), atribuindo-se a sua origem à três fatores: 1) o regime de cheias somado as altas taxas de evaporação; 2) O pH elevado das lagoas e 3) A presença de altos teores de Fe, Al e matéria orgânica. Na floresta Amazônica, por sua vez, observam-se elevadas emissões de Hg devidas às queimadas. Todavia, nenhum estudo investigou as mudanças que essas provocam na EQ ou na composição isotópica (CI) do Hg. Para sanar essa lacuna, efetuaram-se experimentos de queima programada em duas localidades na Amazônia Legal, nas quais amostras de liteira, solos e cinzas foram coletadas. Analisou-se a CI por MC-ICP-MS e a EQ por GC-ICP-MS. Os resultados da CI indicaram que durante as queimadas o Hg não se fraciona isotopicamente de maneira acentuada. Assim, estimou-se que as emissões de Hg possuem uma assinatura isotópica que corresponde a uma mistura das assinaturas da liteira e dos solos. Para a EQ, observou-se que as folhas captam o metilmercúrio (MMHg) atmosférico e o depositam nos solos, que o acumulam com o tempo. Após a queimada, o MMHg da liteira pode ser majoritariamente perdido enquanto aquele encontrado nos solos pode ser apenas parcialmente perdido
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Silva, Gabriela Machineski da. "Diversidade taxonômica e funcional de comunidades microbianas em lagoas salino-alcalinas do Pantanal brasileiro." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/11/11138/tde-29042015-151009/.
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As lagoas salino-alcalinas (salinas) da sub-região Nhecolândia do Pantanal, Mato Grosso do Sul, combinam valores de pH elevados com a presença de altas concentrações de sal, assemelhando-se aos lagos de soda da África Oriental. O entendimento atual dos mecanismos físicos, químicos e biológicos nestes ambientes extremos do Brasil é limitado. Embora os micro-organismos estejam envolvidos nos processos biogeoquímicos em ecossistemas aquáticos, investigações sobre os grupos bacterianos que contribuem para a diversidade e funções específicas nessas salinas inexistem. Assim, a presente dissertação centrou-se na avaliação da comunidade bacteriana de duas salinas (Salina Verde e Salina Preta), localizadas na sub-região da Nhecolândia. Especificamente, investigou-se a diversidade e a estrutura das comunidades bacterianas, os perfis metabólicos das lagoas e genes funcionais que codificam enzimas relacionadas a transformação do nitrogênio, mercúrio, selênio e arsênio. As amostras de água foram coletadas durante a estação seca (setembro de 2012) na Salina Verde (pH 9,5, E.C. 2575 mS cm-1), caracterizada pela presença constante de floração de cianobactérias e na Salina Preta (pH 8,9, E.C. 1500 mS cm-1), sem registro de ocorrência de floração. As amostragens foram realizadas em triplicatas em duas profundidades (superfície e fundo) e duas vezes no dia (10:00 h e 15:00 h) devido à ocorrência natural de saturação de oxigênio observada na Salina Verde. O DNA total de cada amostra ambiental foi extraído e a diversidade bacteriana e funcionalidade foram acessadas por pirosequenciamento do gene de 16S RNAr e sequenciamento metagenômico. A análise de PCR quantitativa do gene de 16S RNAr foi realizada de forma a quantificar a comunidade bacteriana. A abundância bacteriana foi maior na Salina Verde do que na Salina Preta (1010 e 109 cópias mL-1, respectivamente). As sequências parciais do gene de 16S RNAr obtidas no pirosequenciamento mostraram a dominância de táxons do gênero Anabaenopsis sp. na floração da Salina Verde, englobando até 92% do total de sequências. A comunidade bacteriana da Salina Preta apresentou os maiores índices de diversidade e riqueza, sendo dominantes os filos Proteobacteria, Bacteroidetes, Acidobacteria e Verrucomicrobia. Apenas a Salina Preta mostrou diferenças na comunidade bacteriana de acordo com as profundidades amostradas. Na superfície desta lagoa, os filos Actinobacteria e Verrucomicrobia predominaram, enquanto no fundo, prevaleceram os filos Proteobacteria e Chlamydiae. A temperatura foi detectada como o fator abiótico que influenciou a heterogeneidade espacial da Salina Preta. Por sua vez, a alcalinidade e o pH foram os fatores que impulsionaram as diferenças e variações das comunidades bacterianas em ambas as lagoas. Genes bacterianos envolvidos nos ciclos biogeoquímicos do nitrogênio, mercúrio e arsênio foram encontrados nas salinas Verde e Preta, sugerindo uma elevada redundância funcional nas transformações desses elementos. Não foram encontrados genes microbianos envolvidos no ciclo do selênio. Os dados gerados revelaram uma comunidade microbiana taxonômica e funcionalmente complexa que habita as salinas. Os resultados deste estudo fornecem uma avaliação aprofundada baseada em abordagens independentes de cultivo, sendo este um passo importante na compreensão da dinâmica funcional desses ambientes no Pantanal brasileiro.<br>The saline-alkaline lakes (salinas) of the Nhecolândia sub-region of the Pantanal, Mato Grosso do Sul state, combine high pH values with the presence of high salt concentrations, resembling the soda lakes of East Africa. The current understanding of physical, chemical and biological mechanisms in these extreme environments is limited. Although microorganisms are involved in biogeochemical processes in aquatic ecosystem, researches on the bacterial groups that contribute to diversity and specific functions in these salinas are scarce. This dissertation therefore focused on the evaluation of bacterial community of two salinas (Salina Verde and Salina Preta) located in the Nhecolândia subregion. Specifically, it was investigated the diversity and structure of bacterial communities, the metabolic profile of the lakes and functional genes that encode the nitrogen, mercury and arsenic-transforming enzymes. Water samples were collected during the dry season (September 2012) from Salina Verde (pH 9.5, E.C. 2575 mS cm-1), characterized by constant presence of cyanobacterial bloom, and from Salina Preta (pH 8.9, E.C. 1500 mS cm-1), with no report of bloom occurrence. Triplicate samplings were carried out in two depths (surface and bottom) and twice a day (10 AM and 3 PM) due to naturally occurrence of oxygen saturation, observed at Salina Verde. Total DNA of each environmental sample was extracted and bacterial diversity and functionality were accessed by 16S rRNA gene pyrosequencing and metagenomic sequencing. Analysis of quantitative PCR of the 16S rRNA gene was performed in order to quantify the bacterial community. Bacterial abundance was higher in the Salina Verde than in the Salina Preta (1010 and 109 copies mL-1, respectively). The partial sequences of the 16S rRNA gene obtained in the pyrosequencing revealed the genus Anabaenopsis sp. as the dominant taxa in the Salina Verde bloom, encompassing up to 92% of the total bacteria. Bacterial community of the Salina Preta showed the highest diversity and richness index, with dominant phyla Proteobacteria, Bacteroidetes, Acidobacteria and Verrucomicrobia. Only the Salina Preta showed differences in bacterial community in accordance with the depths sampled. On the surface of this lake, the phyla Actinobacteria and Verrucomicrobia predominated, while in the bottom, Proteobacteria and Chlamydiae prevailed. The temperature was detected as the abiotic factor influencing the spatial heterogeneity at Salina Preta. On the other hand, alkalinity and pH were the factors driving the differences and variation of bacterial community in both lakes. Bacterial genes involved in the biogeochemical cycles of nitrogen, mercury and arsenic were found in Salina Verde and Salina Preta, suggesting a high metabolic redundancy in the transformation these elements. No microbial genes involved in selenium cycle were found. The data showed a taxonomic and functional complex microbial community inhabiting salinas. The results of this study provide a detailed assessment based on culture-independent approaches, which is a stepping stone to understand the functional dynamics of these environments in the Brazilian Pantanal.
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Castro, Neemias de [UNESP]. "Cádmio, chumbo, cromo, mercúrio e níquel nos rios do estado de São Paulo e em peixes do Rio Sorocaba (São Paulo, Brasil)." Universidade Estadual Paulista (UNESP), 2002. http://hdl.handle.net/11449/122191.
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000185379.pdf: 993355 bytes, checksum: 10c9ef2e5920d4d73ea7a3e5ec954ae8 (MD5)<br>Com o objetivo de verificar os níveis de concentração de alguns metais pesados em peixes do Rio Sorocaba e avaliar se estão contaminados e se constituindo em risco para a saúde de quem os pesca e consome, foram estudados 63 exemplares de peixes capturados em quatro pontos ao longo desse recurso hídrico e pesqueiro, quanto à presença de cádmio, chumbo, cromo, níquel e mercúrio, com ênfase neste último, por ser reconhecidamente o mais tóxico e com maiores possibilidades de contaminar peixes. Constatou-se, analisando amostras de músculo por espectrometria de absorção atômica - vapor frio, que os peixes do rio Sorocaba não apresentam concentrações proibitivas de nenhum dos cinco metais pesados estudados, estando seguros para o consumo humano. Para subsidiar o objetivo principal deste trabalho, foi feito estudo crítico dos dados levantados pela CETESB nos Relatórios da Qualidade das Águas Interiores do Estado de São Paulo nos anos de 1997 a 2000 quanto ao cádmio, chumbo, cromo, níquel e mercúrio. O estudo aponta que nas 20 Unidades de Gerenciamento de Recursos Hídricos do Estado de São Paulo monitoradas pela CETESB ocorreram casos de desconformidades, frente aos padrões legais para a classe dos rios, para um ou mais dos cinco metais pesados avaliados, sendo recomendável uma melhoria das ações de controle para esses metais em todas as regiões.<br>To verify the levels of concentration of some heavy metals in fishes from Sorocaba river (São Paulo, Brazil) and evaluate if this contamination offers health risks to the fishermen, 63 samples of fishes collected from four points along the river were studied for cadmium, lead, chromium, nickel and mercury, with emphasis in this last, since it is the most toxic and most probable as a fish contaminant. Analyzing muscle samples by cold vapor atomic absorption spectrometry it was shown that the fishes are not contaminated. None of the five metals studied were present in prohibitive level and the fishes could be judged secure for human consume. It was also analyzed data from four years of cadmium, lead, chromium, nickel and mercury monitoring made by CETESB, from 1997 to 2000, in water from the main rivers of the State of São Paulo. The study pointed out that the majority of the monitored rivers still present contamination by those metals in a level that requires an improvement of the pollution control actions.
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Castro, Neemias de. "Cádmio, chumbo, cromo, mercúrio e níquel nos rios do estado de São Paulo e em peixes do Rio Sorocaba (São Paulo, Brasil) /." Rio Claro : [s.n.], 2002. http://hdl.handle.net/11449/122191.
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Orientador: Walter Barrella<br>Banca: Roberto Naves Domingos<br>Banca: João Donato Scorvo Filho<br>Resumo: Com o objetivo de verificar os níveis de concentração de alguns metais pesados em peixes do Rio Sorocaba e avaliar se estão contaminados e se constituindo em risco para a saúde de quem os pesca e consome, foram estudados 63 exemplares de peixes capturados em quatro pontos ao longo desse recurso hídrico e pesqueiro, quanto à presença de cádmio, chumbo, cromo, níquel e mercúrio, com ênfase neste último, por ser reconhecidamente o mais tóxico e com maiores possibilidades de contaminar peixes. Constatou-se, analisando amostras de músculo por espectrometria de absorção atômica - vapor frio, que os peixes do rio Sorocaba não apresentam concentrações proibitivas de nenhum dos cinco metais pesados estudados, estando seguros para o consumo humano. Para subsidiar o objetivo principal deste trabalho, foi feito estudo crítico dos dados levantados pela CETESB nos Relatórios da Qualidade das Águas Interiores do Estado de São Paulo nos anos de 1997 a 2000 quanto ao cádmio, chumbo, cromo, níquel e mercúrio. O estudo aponta que nas 20 Unidades de Gerenciamento de Recursos Hídricos do Estado de São Paulo monitoradas pela CETESB ocorreram casos de desconformidades, frente aos padrões legais para a classe dos rios, para um ou mais dos cinco metais pesados avaliados, sendo recomendável uma melhoria das ações de controle para esses metais em todas as regiões.<br>Abstract: To verify the levels of concentration of some heavy metals in fishes from Sorocaba river (São Paulo, Brazil) and evaluate if this contamination offers health risks to the fishermen, 63 samples of fishes collected from four points along the river were studied for cadmium, lead, chromium, nickel and mercury, with emphasis in this last, since it is the most toxic and most probable as a fish contaminant. Analyzing muscle samples by cold vapor atomic absorption spectrometry it was shown that the fishes are not contaminated. None of the five metals studied were present in prohibitive level and the fishes could be judged secure for human consume. It was also analyzed data from four years of cadmium, lead, chromium, nickel and mercury monitoring made by CETESB, from 1997 to 2000, in water from the main rivers of the State of São Paulo. The study pointed out that the majority of the monitored rivers still present contamination by those metals in a level that requires an improvement of the pollution control actions.
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Barbour, Reinaldo. "Avaliação crítica de métodos analíticos para determinação de arsênio e mercúrio em amostras de ácido sulfúrico de uma metalurgia de cobre." Programa de Pós-Graduação em Química da UFBA, 2007. http://www.repositorio.ufba.br/ri/handle/ri/10010.
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Previous issue date: 2007<br>Foram avaliados os desempenhos de três métodos analíticos baseados em: (I) espectrometria de absorção atômica com geração de vapor frio/hidretos por injeção de fluxo (FI-HG-AAS); (II) espectrometria de emissão óptica com plasma indutivamente acoplado com geração de vapor frio/hidretos em modo contínuo (HG-ICP OES) e, (III) espectrometria de emissão óptica com plasma indutivamente acoplado com introdução da amostra por nebulização pneumática (PN-ICP OES) para determinação de As e Hg em amostras de ácido sulfúrico. Os resultados obtidos indicaram que os três métodos avaliados podem ser utilizados para a determinação de As e Hg em ácido sulfúrico, com maior vantagem para o método (I), levando em conta o LOQ e o custo da analise. Os outros dois métodos possuem as vantagens da determinação simultânea dos dois analitos, a eliminação da etapa de préredução do arsênio e redução de dez vezes no volume final da amostra em relação ao método (I).O método (III) é a único que não utiliza geração de vapor frio/hidretos e portanto não consome NaBH4. Os limites de detecção para As e Hg, calculados como 3 vezes os desvios padrão do branco para os três métodos foram: método (I) As 0,07 e Hg 0,09 µg L-1; método (II) As 0,30 e Hg 0,18 µg L-1 e método (III) As 5 e Hg 3 µg L-1. Os desvios padrão relativos, RSD, para os três métodos foram, respectivamente, As 1,8 (5,0 µg L-1); 1,5 (50 µg L-1); 4,0 (50 µg L-1) e Hg 3,1 (5,0 µg L-1); 4,3 (5,0 µg L-1); 4,3 (5,0 µg L-1). As concentrações do NaBH4 utilizadas nos métodos FI-HG-AAS e HG-ICP OES, foram respectivamente, 0,05 e 1,5 % m v-1.<br>Salvador
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Macedo, Luciene Fagundes Lauer. "Remoção de mercúrio e arsênio em cação-azul, Prionace glauca." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/9/9131/tde-19012011-102635/.
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Os cações são importantes recursos pesqueiros que podem apresentar concentrações de mercúrio (Hg) e arsênio (As) muitas vezes acima do limite de tolerância, o que os tornam impróprios como alimento. No meio aquático estes contaminantes são convertidos em espécies orgânicas, em especial metilmercúrio (MeHg) e arsenobetaína (AB), respectivamente. O MeHg é neurotóxico, sendo o sistema nervoso em desenvolvimento o mais susceptível. A AB é pouco tóxica, no entanto, o As inorgânico está envolvido em processos de estresse oxidativo, mutagênese e principalmente carcinogênese. Neste trabalho, foi avaliada a eficiência da cisteína na remoção de Hg, a ocorência de As total e inorgânico, e a redução de sua concentração com o emprego de borohidreto de sódio e de preparos para o consumo. A redução máxima de Hg, de 59,4%, com cisteína a 0,5% em pH 5,0, não foi reproduzida quando pretendida a reutilização da solução do aminoácido, importante do ponto de vista prático. O cação-azul continha elevados níveis de As total, 1,98 a 22,56 µg/g (base úmida), que foram removidos com borohidreto de sódio em 99%, demonstrando a alta potencialidade do método usado. O As inorgânico, presente na quantidade média de 0,0086 µg/g (base úmida), foi reduzido em 27,7%. O preparo para o consumo, por cozimento em água, do cação-azul em cubos (1-2 cm3), resultou em maior remoção de As total, de 65,9 a 71,2%; no cação grelhado a redução foi de 55,4 a 60,2%. As amostras, grelhadas ou cozidas, adicionadas de sal e limão enriquecido com ácido ascórbico, e as grelhadas contendo sal e sal com limão, apresentaram redução na concentração de As inorgânico de 30,1 a 42,8%.<br>The shark are important fishery resources that may have concentrations of mercury (Hg) and arsenic (As) often above the limit of tolerance, which makes them unsuitable as food. In the aquatic environment these contaminants are converted to organic species, particularly methylmercury (MeHg) and arsenobetaína (AB), respectively. The MeHg is neurotoxic, and the developing nervous system more susceptible. AB is slightly toxic, however, the inorganic As is involved in processes of oxidative stress, mutagenesis and carcinogenesis mainly. In this study, we evaluated the efficiency of cysteine to remove mercury, the occurrence of the total and inorganic As, and the reduction of their concentration with the use of sodium borohydride and preparations for consumption. The maximum reduction of Hg, 59.4%, with 0.5% cysteine at pH 5.0, was not reproduced when you want to reuse the solution of the amino acid, important practical point of view. The blue-shark contained high levels of the total As, 1.98 to 22.56 µg/g (wet weight), which were removed with sodium borohydride in 99%, demonstrating the high potential of the method used. The inorganic As, present in the average amount of 0.0086 µg/g (wet weight) was reduced in 27.7%. Preparation for consumption by baking in water, the blue-shark into cubes (1-2 cm3) resulted in greater removal of the total As, 65.9 to 71.2%; in the grilled shark the reduction was 55,4 to 60.2%. The samples, grilled or baked, added salt and lemon enriched with ascorbic acid, and the grilled containing salt and salt with lemon, presented reduction in the concentrations of inorganic As from 30.1 to 42.8%.
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Sun, B. "Speciation of arsenic, selenium, lead, and mercury with capillary electrophoresis." Thesis, 2004. https://eprints.utas.edu.au/22121/7/Sun_whole_thesis_ex_pub_mat.pdf.
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This work deals with speciation of elements of environmental concern (arsenic, selenium, lead and mercury) using a variety of capillary electrophoresis (CE) methods combined with various on-capillary approaches to enhance the method sensitivity.
Capillary zone electrophoresis (CZE) with UV-detection was used for the determination of arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, p-aminophenylarsonic acid, 4-hydroxy-3-nitrobenzearsonic acid, 4-nitrophenylarsonic acid, phenylarsonic acid and phenylarsine oxide. The influence upon the method performance criteria of operational parameters such as electrolyte pH and composition, applied voltage, as well as electroosmotic flow (EOF) reversal protocols was investigated. Both the counter-BOP separation mode applied in fused-silica (FS) capillaries, and the co-EOF separation mode performed in a poly(diallydimethylammonium) chloride (PDDAC) coated capillary with reversed EOF were used. The background electrolyte (BGE) composition found to provide optimal separation was 20 mM carbonate buffer at pH 10.0. This method was applied to the determination of four aryl arsenic compounds in animal feed. The co-EOF method was also used for the simultaneous determination of nine arsenic and selenium compounds (arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, selenate, selenite, selenocystine, selenomethionine and selenocystamine). The BGE composition found to provide optimal separation was 15 mM phosphate buffer at pH 10.6. Arsenic and selenium species were detected at 195 nm and 200 nm, respectively.
Dithizon sulfonate (DzS) and ammonium bis(2-hydroxyethyl)dithiocarbamate (HEDTC) were used to derivatise mercury species to form complexes which have strong UV absorbance. These complexes were separated using CZE and microemulsion electrokinetic chromatography (MEEKC). Microemulsions having a range of pH 3.0-11.0 were used in MEEKC to achieve the optimal separation conditions. A FS capillary and successive polymer and microemulsion dynamically coated (SPMEC) capillaries were used in MEEKC. However, a fully suitable derivatisation reagent for organolead species has not yet been found.
In this research, stacking mechanisms and concentration sensitivity enhancement factors were discussed and compared for (1) normal stacking mode (NSM, sometimes also referred to as field amplified stacking) in an uncoated FS capillary in the counter-EOF mode, (2) large volume sample stacking (LVSS) with polarity switching, and (3) the less often applied stacking method of co-EOF NSM stacking with EOF reversal using a PDDAC-coated capillary. Of these three stacking methods, L VSS with polarity switching gave the lowest limit of detection (LOD), while co-EOF NSM stacking was used to simultaneously pre-concentrate both cationic and anionic target analytes.
The use of a high sensitivity detection cell (HSDC) further reduced the LOD of the target analytes by a factor of 5-8 times. By combining LVSS and HSDC, LODs of arsenic species could be reduced by a factor of 218-311, being 1.74, 4.87, 1.99 and 2.80 μg/L for arsenite, arsenate, dimethylarsinic acid and monomethylarsonic acid, respectively. The method was demonstrated to be applicable to the determination of the target analytes in tap water, sediment and a selenium nutrition supplement sample, the sample matrix did not interfere with the determinations.
Sweeping was used in MEEKC to improve the sensitivity of those analytes which have a high retention factor in the mi cell e. In this work, the LOD of the HEDTC phenyl mercury complex was significantly improved by a factor of 5 .4.
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Lai, Li-Chi, and 賴力綺. "Bioaccessibility, mobility, and health risk assessment of arsenic and mercury in soils." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/62296811616771502190.
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碩士<br>國立臺灣大學<br>環境工程學研究所<br>104<br>Taiwan Environmental Protection Administration has declared more than 2,900 control and remediation sites due to soil and groundwater contamination. People who live on or close to these contaminated sites may have high exposure risk. Moreover, higher-frequency hand-to-mouthing behaviors could lead children under six years old to greater health risk than adults due to direct ingestion. Hence, health risk assessment is necessary for children living in the neighborhood of the contaminated sites. However, the assessment based on total content of contaminants may overestimate the risk; consequently, it is important to determine bioavailable metals in soils. Although in-vivo approaches reflect quasi-physiological conditions, these methods are expensive and time-consuming. Therefore, in-vitro methods are developed and recognized as fast screening tools in assessing bioaccessibility of metals in the soils of contaminated sites.
In this study, eight asenic (As)-contaminated and mercury (Hg)-contaminated soils were collected from four different sites in Taiwan (i.e., Guandu, Cianjhen, Anshun and Chishan-Yen sites). One of the objectives is to provide more proper results for exposure assessment via acquisition of As and Hg bioaccessibility by using two in-vitro assays, namely physiologically based extraction test (PBET) and simplified bioaccessibility extraction test (SBET). Moreover, sequential extraction procedure (SEP) was employed to understand the solubilities and motilities of As and Hg in the soils. The experimental results showed that positive significant (P<0.05) relationships were found between As proportions in fraction 1, fraction 2 of SEP and As bioaccessibility; the positive significant (P<0.01) relationships was also established between Hg proportions in fraction 1, fraction 2 of SEP and Hg bioaccessibility. The soil properties (e.g., organic carbon and clay content) had significant (P<0.05) correlation with As and Hg bioaccessibility. As expected, the risk results after adjustment by bioaccessibility were lower than that obtained based on total metal contents. Results obtained in this research provide suggestions to the decision makers on setting new strategies in the risk management of metal-contaminated soil sites.
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Hsieh, Chun-Yu, and 謝春宇. "Measurement of urine concentrations of arsenic, cadmium and mercury: A systematic review." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/gmgc6h.
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碩士<br>中國醫藥大學<br>公共衛生學系碩士班<br>105<br>Abstract
Background
The feasibility of common urine concentration-dilution adjustment methods remains vaguely defined in arsenic(As), cadmium(Cd) and mercury(Hg) which further compromised effective exposure measurements and subsequent risk assessments.
Objectives
The aim of this review was to summarize the available information regarding the performance appraisal of common adjustment methods on measuring levels of urine As, Cd, and Hg.
Methods
We searched PubMed/MEDLINE, Embase, LILIAC, Web of Science, and TOXNET for articles related to evaluation of at least two different urine adjustment methods. Data on study design, population characteristics, urine specimen collection, statistical evaluation on the performance of selected adjustment method, and preferred recommendation were extracted.
Results
We found a total of 41 papers. Nine papers specifically evaluated the performance of adjustment methods for arsenic, 14 for cadmium, 12 for mercury, and 6 for multiple metals. The median sample size for arsenic was 131; cadmium, 105; mercury, 27. Studies were heterogeneous regarding population selection, urine collection, urine quality control, statistical comparison among selected adjustment methods, and presentation of results. Only two studies evaluated the performance of urine osmolality adjustment. The majority of studies suggested adopting unadjusted values to estimate urine arsenic levels using first morning voided urine. For cadmium, using urine specific gravity or urine creatinine to adjust spot urine concentration/dilution were frequently recommended. Regarding mercury, urine creatinine adjustment was advocated by most studies enrolled in this review.
Conclusion
A critical knowledge gap exists in our understanding of the role of urine adjustment methods in exposure and risk assessment in environmental science. Develop international standardized protocols are an urgent need to facilitate exposure quantification, data comparison, and effective risk communication for public health.
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Carneiro, Manuela Andreia Gonçalves. "Biomonitoring of arsenic, cadmium, lead and mercury with raptors from the Iberian Peninsula." Doctoral thesis, 2016. http://hdl.handle.net/10348/5537.
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Tese de Doutoramento em Ciências Veterinárias - Clínica<br>A poluição ambiental é um problema de crescente relevância por constituir uma ameaça na estabilidade dos ecossistemas e consequentemente afetar a saúde humana. Entre os diferentes tipos de poluentes, os metais tóxicos têm merecido grande preocupação porque persistem muito tempo no meio ambiente, são ubíquos e apresentam uma pronunciada bioacumulação nos organismos e biomagnificação na cadeia alimentar. Por estas razões, a monitorização destes poluentes é de extrema importância. As aves de rapina por estarem no topo da cadeia alimentar e apresentarem uma vida longa, são adequadas para a monitorização de poluentes bioacumuláveis e biomagnificáveis como os metais tóxicos.
Na Península Ibérica, principalmente em Espanha, têm sido realizados alguns estudos de biomonitorização de metais com aves de rapina, em determinadas áreas geográficas. Contudo, em Portugal este tipo de estudos é escasso e em Espanha ainda faltam informações relativamente à exposição de algumas espécies e em algumas áreas geográficas.
O principal objetivo do presente trabalho foi avaliar o grau e tipo de exposição aos principais metais e metaloides tóxicos em três espécies de aves de rapina e assim determinar indiretamente a qualidade ambiental dos ecossistemas terrestres relativamente a estes poluentes. Para alcançar este propósito, utilizando a técnica de espetrometria de massa com plasma acoplado indutivamente (ICP-MS), determinaram-se as concentrações de arsénio (As), cádmio (Cd), mercúrio (Hg) e chumbo (Pb) em amostras de sangue, fígado e rim obtidas a partir da espécie Águia-d’asa-redonda (Buteo buteo) e em amostras de sangue do Milhafre-preto (Milvus migrans) admitidos em diferentes centros de reabilitação de animais selvagens (CRAS) de Portugal. Também foram analisadas amostras de sangue de Grifos (Gyps fulvus) capturados e admitidos em CRAS da Península Ibérica para determinar as concentrações de Cd, Hg e Pb.
Na espécie Águia-d’asa-redonda, o metal mais identificado foi o Hg e o menos identificado foi o As, nos três tipos de amostras recolhidas. De entre as diferentes amostras analisadas, as concentrações mais elevadas foram identificadas no rim para todos os elementos, o que sugere a existência de uma acumulação dos metais e do As neste órgão. As aves adultas apresentaram concentrações hepáticas e renais de Cd mais elevadas do que as juvenis. As concentrações sanguíneas de Pb e Hg parecem apresentar uma associação com a época de caça e a muda das penas, respetivamente. Considerando a espécie Milhafre-preto, as concentrações sanguíneas de metais mais elevadas foram obtidas para o Pb e Hg nas aves que vivem em liberdade. O grupo de aves que vive em cativeiro apresentou as concentrações mais baixas para todos os elementos químicos estudados, tendo-se observado diferenças significativas (p<0.01) com as aves de vida livre apenas para o Hg e Pb.
Nos Grifos avaliados não foram detectadas concentrações sanguíneas de Cd e de Hg em mais de 95% dos animais, no entanto o Pb foi identificado em todos os animais. A intoxicação por Pb foi confirmada em três Grifos. A população de Grifos capturada na Catalunha (Espanha) apresentava as concentrações sanguíneas de Pb mais elevadas possivelmente devido ao contexto ecológico do habitat destas aves: área urbana e industrial, onde as lixeiras parecem fornecer uma fração significativa das suas necessidades alimentares. Os Grifos admitidos aos CRAS apresentaram concentrações de Pb sanguíneas significativamente mais baixas (p<0.05) que os animais capturados. Esta diferença pode ser explicada pelo facto da desnutrição ter sido a principal causa de admissão destes animais nos CRAS. Estes resultados indicam que os Grifos admitidos aos CRAS talvez não sejam representativos das populações locais quanto à exposição recente ao Pb.
Comparando as três espécies estudadas, a Águia-d’asa-redonda apresentou as concentrações sanguíneas de Hg mais elevadas, o Grifo as de Pb e o Milhafre-preto as de As. O Cd sanguíneo não foi detetado numa grande percentagem de animais (>90%) nas três espécies de rapinas estudadas. Esta diferença interespecífica observada para o As, Hg e Pb sanguíneo parece estar relacionada principalmente com diferenças nos hábitos alimentares.
Perante os nossos resultados pode-se afirmar que embora as aves de rapina estejam mais predispostas aos processos de biomagnificação que podem ocorrer na cadeia alimentar, as concentrações dos metais analisados e do As identificadas são compatíveis com uma exposição de baixo risco. Contudo, na Águia-d’asa-redonda os resultados obtidos sugerem uma exposição crónica a estes poluentes e o potencial risco do Hg deve ser considerado uma vez que esta espécie apresentou níveis relativamente elevados deste metal. O risco de toxicidade pelo Pb pode ser elevado principalmente no Grifo, e poderá ser um factor limitante para a conservação desta espécie.<br>Pollution is a problem of growing relevance because it is a serious threat to the stability of ecosystems and it affects the human health. Unlike many other pollutants, toxic metals have been contaminants of great concern because they are persistent, ubiquitous and they have a pronounced bioaccumulation in tissues and biomagnification in food chains. For these reasons, monitoring the toxic metals has become increasingly important. Raptors are considered especially suitable for monitoring bioaccumulable and biomagnificable pollutants mainly due to their position at the top of trophic chain and their susceptibility to bioaccumulate contaminants over time.
In the Iberian Peninsula, although several biomonitoring studies using several raptor species have been performed in Spain, still remains lack of information regarding the exposure to metals in some raptor species and about environmental contamination in some geographical areas. In Portugal, biomonitoring studies with raptors have been scarce.
The main goal of the present work was to evaluate in three raptors species the degree and type of exposure to the toxic metals and arsenic (As) and thus indirectly determine the environmental quality of terrestrial ecosystems related to these pollutants. For this purpose, the concentrations of As, cadmium (Cd), mercury (Hg) and lead (Pb) were determined by inductively coupled plasma mass spectrometry (ICP-MS) in blood, liver and kidney samples taken from Common buzzards (Buteo buteo) and in blood samples taken from captive and free-living Black kites (Milvus migrans) admitted to different Portuguese wildlife rehabilitation centres (WRCs). Blood samples taken from Griffon vultures (Gyps fulvus) caught in the wild or admitted to WRCs in the Iberian Peninsula were also analysed for Cd, Hg and Pb.
In the Common buzzard, Hg and As were the elements which appeared in the highest and lowest concentrations, respectively. The kidney was the analyzed sample which showed the highest concentrations of each element, what suggests an accumulation of the toxic metals. Adults’ Common buzzards showed higher hepatic and renal Cd concentrations than juveniles, because this metal is accumulated throughout the life span of the birds. Blood Pb and Hg concentrations seem to show an association with the hunting and molting season, respectively.
Regarding the Black kite, the highest mean blood concentrations were found for Pb in free-living birds followed by Hg. The captive birds had the lowest blood concentrations for all analyzed toxic elements, but significant differences (p<0.01) with the free-living birds were only observed for Hg and Pb. Therefore, an available source of Pb and Hg seems to be present in the habitat of the Black kite. In the studied Griffon vultures, Cd and Hg were not detected in more than 95% of the birds, while Pb was detected in all birds. Pb poisoning was confirmed in three Griffon vultures. The population of vultures captured in Catalonia (Spain) has the highest mean blood Pb concentration possible due to the ecological context of the bird’s habitat: an urban and industrial area, where rubbish dumps provide a significant fraction of their trophic needs. Birds admitted to WRCs had significantly lower Pb concentrations (p<0.05) than animals caught in the wild. This may be explained by the fact that malnutrition was the main cause of their admission to WRCs, once the ingestion has been described as the most significant pathway for Pb exposure in raptors. Therefore the Griffon vultures admitted to WRCs do not seem to be representative of the local free-living populations in terms of recent Pb exposure.
The comparison between the three species shows that the Common buzzard had the highest blood Hg concentrations, while the highest blood Pb concentrations were obtained for Griffon vulture. Blood As was higher in the free-living Black kites. A high percentage of birds (>90%) with not detected blood Cd concentrations were found in the three species. The interspecific difference observed for blood As, Hg and Pb concentrations seems to be mainly related with the different dietary habits.
Although raptors are potentially exposed to any biomagnification processes that may occur in a food web, the concentrations of metals and As detected in the samples collected from the three raptor species could be considered compatible with a low-risk exposure. However, chronic exposure to these metals was verified for Common buzzard and the potential risk of Hg should be considered due to the relatively high Hg concentrations found in this species. In certain cases, Pb can be related to toxic side effects and it could be a limiting factor for the Griffon vulture conservation.
Keywords: Toxic metals, Common buzzard, Black kite, Griffon vulture, Portugal, Spain.<br>This work was funded by Fundação para a Ciência e a Tecnologia, Ministério da Educação e Ciência (Portugal).
- SFRH/BD/62115/2009-
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Barnett, Anne. "Quantum well intermixing by ion implantation." Thesis, 2002. http://hdl.handle.net/1885/41355.
Full textAbstract:
The work carried out in this study explored the phenomenon of ion implantation induced intermixing in quantum well structures. Two quantum well systems were investigated; the unstrained GaAs/Al_xGa_(1-x)As system, and the strained In_xGa_(1-x)As/GaAs system. Previous results from proton and arsenic implantation into these systems were verified, and new work on Boron implantation was conducted to test the medium mass ion regime.
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Han, Dong Suk. "Sorption of Arsenic, Mercury, Selenium onto Nanostructured Adsorbent Media and Stabilization via Surface Reactions." 2009. http://hdl.handle.net/1969.1/ETD-TAMU-2009-12-7357.
Full textAbstract:
The overall goal of this study is to evaluate the ability of novel nanostructured adsorbent media (NTAs, iron sulfides (FeS2 and FeS)) to remove arsenic, selenium and mercury from ash and scrubber pond effluents. The NTAs aim to enhance arsenic removal from solution compared to conventional adsorbents. The iron sulfides are expected to produce stable residuals for ultimate disposal after removing As, Se and Hg from solution, so that removal of these compounds from wastewaters will not result in contamination of soils and groundwaters. Methods for reliably and economically producing these materials were developed. The synthesized NTAs and iron sulfides were characterized by surface analysis techniques such as XRD, FT-IR, SEM-EDS, TEM, XPS, AFM and N2-adsorption. These analyses indicated that Ti(25)-SBA-15 has highly ordered hexagonal mesopores, MT has interparticle mesopores, pyrite (FeS2) forms crystalline, nonporous rectangular nanoparticles (<500 nm), and mackinawite (FeS) forms amorphous, nonporous nanoparticles (<100 nm).
Kinetic and equilibrium tests for As(III, V) removal were conducted with NTAs over a range of pH (4, 7, 9.5). The rates of arsenic uptake were very fast and followed a bi-phasic sorption pattern, where sorption was fast for the first 10 minutes, and then slowed and was almost completed within 200 minutes. Distinct sorption maxima for As(III) removal were observed between pH 7 and pH 9.5 for MT and between pH 4 and pH 7 for Ti(25)-SBA-15. The amount of As(V) adsorbed generally decreased as pH increased. In addition, a surface complexation model (SCM) based on the diffuse layer model (DLM) was used to predict arsenic adsorption envelopes by NTAs under various environmental conditions. The SCM for As(III, V) adsorption by NTAs demonstrated the role of mono- and bidentate surface complexes in arsenic adsorption.
A batch reactor system was employed in an anaerobic chamber to conduct experiments to characterize both the removal of As, Se, Hg from solution and their subsequent reactions with iron sulfides. Experiment variables for removal experiments included: contaminant valence state (As(V), As(III), Se(VI), Se(IV), Hg(II)); adsorbent/reactant type (FeS, FeS2); adsorbent/reactant concentration; pH (7, 8, 9, 10); and competing ion (SO42-) concentration (0, 1, 10 mM). Experimental variables for reaction experiments were reaction time (up to 30 days) at pH 8 and oxidation states of contaminants. In addition, the stability of iron sulfides (FeS2, FeS) combined with target compounds was investigated by measuring the ability of the target compounds to resist release to the aqueous phase after removal. These experiments showed that iron sulfides were good adsorbent/reactants for target contaminants in spite of the presence of sulfate. This was particularly true at intermediate concentrations of target compounds. The experiments also demonstrated that iron sulfides interacted with target contaminants in such a way to improve their resistance to being released back to solution as pH was changed.
Therefore, this study demonstrates the ability of novel nanostructured adsorbent media to remove arsenic, selenium and mercury from ash and scrubber pond effluents and the ability of iron sulfides to produce residuals that are stable when disposed in landfills.
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Dhinsa, Harkirat S. "Atomic absorption spectroscopic determination of mercury, selenium and arsenic in biological and environmental materials." Thesis, 1998. http://handle.uws.edu.au:8081/1959.7/254.
Full textAbstract:
This thesis carefully investigates some of the limitations of existing methods for atomic spectroscopic determination of mercury, selenium and arsenic in biological and environmental materials. In particular the need for adequate sample preparation to ensure reliable atomic spectroscopic determination of these metalloids was demonstrated extensively. The thesis evaluates four most commonly used wet digestion methods for the accurate determination of mercury in biological and environmental materials by cold vapour atomic absorption spectroscopy. Excellent recovery efficiencies were obtained with this digestion mixture in fish homogenate, horse kidney, soil, canned fish and hair samples for inorganic and organic mercury. The suitability of the digestion method for the reliable determination of mercury in soil, hair and canned fish samples was also demonstrated. Mercury levels in these samples were found within normal acceptable range. The thesis outlines a new simple procedure for overcoming the loss of mercury due to sample charring. It also described a new sample ultrasound low temperature wet digestion method for biological and environmental materials. The main advantage of this approach over other conventional methods is its ability to release all mercury in inorganic form from biological and environmental samples at much lower temperatures than reported earlier
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Lin, Jhih-Min, and 林芷旻. "Determination of mercury, chromium and arsenic species in sludge samples by HPLC-ICP-MS." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/y46q77.
Full textAbstract:
碩士<br>國立中山大學<br>化學系研究所<br>106<br>The first part of research focused on ion-pair reversed-phase chromatography with inductively coupled plasma mass spectrometry for determination of mercury species in sludge samples. The separation of Hg(II), methyl-Hg and ethyl-Hg was performed on a reversed-phase C8 column with 2-mercaptoethanol and MeOH as mobile phase, since mercury had a strong affinity to thiol group of 2-mercaptoethanol. Under the optimized conditions, the separation of three mercury species was completed within 6.5 minutes by using isocratic elution program. The relative standard deviation of the peak heights and areas were less than 1.9% for the study species, and the detection limits of Hg(II), methyl-Hg and ethyl-Hg were found to be 0.013, 0.010 and 0.015 ng mL-1, respectively. In the extraction process, the mercury compounds were efficiently extracted from sludge samples by microwave-assisted extraction method, which using the mobile phase (0.3% (v/v) 2-mercaptoethanol and 3.5% (v/v) MeOH) containing 1.0% (v/v) HCl as the extracted reagent. We obtained an extraction efficiency of greater than 93% under heating at 60℃ for 8 minutes, and the spike recoveries of each individual mercury species were in the range of 95-102% to demonstrate the feasibility of the proposed method for sludge analysis. The research was applied to investigate mercury species in four environmental sludge samples, and results revealed that accumulation in sludge was predominantly Hg(II). While methyl-Hg would present in the high pollution water area, it might result from the microorganisms in downstream sludge which could transform Hg(II) into methyl-Hg.
The second part of research focused on ion-exchange chromatography with inductively coupled plasma mass spectrometry for determination of chromium and arsenic species in sludge samples. The simultaneous separation of Cr(III), Cr(VI), As(III), As(V), AsB, DMA and MMA was performed on an anion-exchange column by using gradient elution program with NH4NO3 as mobile phase, and the separation was using gradient elution program with NH4NO3 as mobile phase, and the separation was completed within 10 minutes. Since the detection of chromium and arsenic may suffer from the spectral interferences 40Ar12C+ and 40Ar35Cl+, a dynamic reaction cell (DRC) with O2 as reaction gas was employed to change the mass-to-charge ratio of analytes orinterfering substances to reduce these interferences, which could decrease the background signal and improve the detection limits. Under the optimized conditions of separation and DRC system, the relative standard deviation of the peak heights and areas were less than 2.7% for the study species, and the detection limits of species were in the range of 0.059-0.072 ng mL-1 for chromium and 0.009-0.015 ng mL-1 for arsenic. In the extraction process, chromium and arsenic species were extracted from sludge samples by microwave-assisted extraction method, which using the mobile phase B (40 mM NH4NO3) containing 1.0% (v/v) HF as the extracted reagent to destroy the sludge matrix. The extraction efficiency of chromium and arsenic were achieved 85% and 100% under heating at 90℃ for 40 minutes. The spike recoveries of each individual species were in the range of 92-106% for chromium and 93-108% for arsenic to demonstrate that the proposed method could be applied to determine chromium and arsenic species in sludge at different water area. The analytical results revealed that accumulation in sludge were predominantly inorganic chromium and arsenic, while the more toxic Cr(VI) and As(III) both existed in the high pollution water area. To sum up, different elemental species were presented which depend on the degree of water pollution and sampling location.
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Schwartz, Grace Ellen. "Biogeochemical Transformations of Trace Element Pollutants During Coal Combustion Product Disposal." Diss., 2015. http://hdl.handle.net/10161/9828.
Full textAbstract:
<p>Coal fired power plants generate approximately 45% of the electricity produced in the United States every year, and each year, over 100 million tons of coal ash are produced as a by-product of electricity generation. Coal ash is a solid waste made up principally of bottom ash, fly ash, and flue gas desulfurization materials. The chemical composition of coal ash varies depending on the feed coal source, combustion parameters, and the presence and type of air pollution control devices that remove contaminants from the flue gas into the solid waste stream. Although a significant portion of coal ash waste is recycled, the majority of coal ash is disposed in landfills and holding ponds. Coal ash impoundments have a long history of environmental degradation, which includes: contaminant leaching into groundwater, the discharge of contaminant-laden effluent into surface waters, and catastrophic impoundment failures and ash spills. Despite these known problems, coal ash is not considered a hazardous waste, and thus is not subject to stringent disposal requirements. The current coal ash management system is based on risk assessments of coal ash that do not include environmental parameters that have a profound impact on coal ash contaminant mobility, particularly for the toxic elements such as mercury, arsenic, and selenium. This dissertation research focused on the biogeochemical transformations of mercury, arsenic, and selenium associated with coal ash materials in an effort to: (1) define the key environmental parameters controlling mercury, arsenic, and selenium fate during disposal and ash spills; and (2) delineate the relationship between coal ash characteristics, environmental parameters, and leaching potential. </p><p> The impact of coal ash on mercury transformations in anaerobic systems was assessed using anaerobic sediment-ash microcosms to mimic an ash spill into a benthic aquatic system. Anaerobic sediments are the primary zones for the microbial conversion of inorganic mercury to methyl mercury (MeHg), a process that is mediated by anaerobic bacteria, particularly sulfate reducing bacteria (SRB). MeHg is a potent neurotoxin that biomagnifies up the aquatic food chain, presenting a human health risk-- especially to children and pregnant women. The results of the sediment-ash microcosm experiments indicated negligible net production of MeHg in microcosms with no ash and in microcosms amended with the low-sulfate/low-Hg ash. In contrast, microcosms amended with sulfate and mercury-rich ash showed increases in MeHg concentrations that were two to three times greater than control microcosms without ash. The enhancement MeHg production in the microcosms was likely due to large quantities of leachable sulfate that stimulated the activity of methylating bacteria. Overall, these results highlight the importance of considering both the geochemical conditions of the receiving environment and the chemical composition of the coal ash in assessing the MeHg potential of coal ash. </p><p> The hypothesis that sulfate-rich coal ash can change sediment microbial communities, enhancing MeHg production, was tested by analyzing coal ash impacts on the SRB community in the sediment-ash microcosms using Terminal Restriction Fragment Length Polymorphism (T-RFLP), Quantitative Polymerase Chain Reaction (q-PCR), and Reverse Transcription-qPCR (RT-qPCR). Coal ash did not appear to cause significant changes to the structure of the overall bacterial community, though results showed that it may have caused a decrease in the evenness for species distribution for both SRB and the overall microbial community. During the five-day incubation experiment, the coal ash had a temporary significant effect on SRB abundance during the first one to two days of the experiment and a more sustained effect on SRB activity. This stimulation of SRB population growth and activity also corresponded with increasing net MeHg production. Overall, results indicate that coal ash amendments do not cause large shifts in the overall microbial community or the SRB community, but results indicate that there are connections between SRB abundance/activity and MeHg production. More research is needed to determine how coal ash directly impacts Hg methylating microorganisms, which include diverse array of microorganisms outside of SRB.</p><p> The effect of aerobic and anaerobic conditions on arsenic and selenium leaching from coal ash in an ash spill scenario was also assessed using sediment-ash microcosms. The fate of arsenic and selenium associated with coal ash is of particular concern due to the leachability of these elements at neutral pH and their tendency to bioaccumulate in aquatic organisms. Both the redox speciation of arsenic and selenium, and the pH of the aquatic system, are known to influence leaching into the environment, yet current environmental risk assessments of coal ash focus on pH alone as the primary driving force for arsenic and selenium leaching from coal ash and do not take into account the effects of anaerobic conditions and microbial activity. In this research, total dissolved concentrations of arsenic and selenium, dissolved speciation of arsenic, and solid phase speciation of selenium were monitored to determine the biogeochemical transformations and leaching of arsenic and selenium under differing redox conditions. The results from the sediment-ash microcosm studies showed that redox potential was the major determinant of arsenic and selenium mobility in the microcosm systems with greater arsenic leaching occurring in anaerobic microcosms and greater selenium leaching occurring in aerobic microcosms. Furthermore, the experiments provided clues to how coal ash influences the geochemistry of the benthic environment and how these influences affect the speciation and longer term solubility of arsenic and selenium. </p><p> Finally, experiments were conducted to determine how differing CaO, SO3, and Fe2O3 concentrations in coal ash affect the release of arsenic and selenium from sediment-ash mixtures in a simulated ash spill environment. Aerobic and anaerobic sediment-ash microcosms were constructed to mimic an ash spill into a benthic aquatic system, and a variety of coal ash materials were tested as amendments, including seven fly ashes, one lime-treated fly ash sample, and two FGD samples. Results showed that, in most cases, the sediment in the microcosm buffered the system at neutral, which counteracted leaching impacts of differing CaO and SO3 concentrations in the microcosms. Regardless of ash material, leaching of selenium was greater under aerobic conditions and was correlated with the total selenium content of the microcosm. Maximum leaching of arsenic occurred in anaerobic microcosms for some ash materials and in aerobic microcosms for other materials, suggesting that ash material chemistry played a significant role in controlling arsenic mobility. In both aerobic and anaerobic microcosms, dissolved arsenic concentration was correlated with total arsenic content of the ash material and in anaerobic microcosms, dissolved arsenic concentrations also correlated with the total iron content of the ash material. Overall, the results of these experiments showed that arsenic and selenium release under environmentally relevant conditions cannot be predicted by the CaO and SO3 content of the ash material. Rather, the total arsenic, total selenium content, and total iron content of the ash material are good predictors of the worst case environmental leaching scenario.</p><p> These investigations illuminated two major conclusions: (1) microbial activity and differing redox conditions are key in determining the impact of coal ash on the environment and in determining the mobility of coal ash contaminants, and (2) coal ash characteristics, such as sulfate and iron content, can change the redox chemistry and microbial activity of the surrounding environment, further influencing the fate of ash contaminants. This work will be useful in designing a framework that accurately predicts the leaching potential of ash contaminants under environmentally relevant conditions. The results will also be helpful in developing treatment technologies for ash impoundment effluent, guiding decisions on ash pond closure and remediation, and in designing long-term monitoring plans and remediation strategies for ash-impacted sites.</p><br>Dissertation
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Lu, Chia-chun, and 呂佳純. "Distributions and Speciation of Mercury and Arsenic in sediments from Kaoping Coastal Areas and Lagoons." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/82859276764773944367.
Full textAbstract:
碩士<br>國立中山大學<br>海洋地質及化學研究所<br>94<br>The purposes of this study are to evaluate and elucidate distribution patterns, speciation and pollution status of As and Hg in coastal sediments. The study focuses on coastal zones off southwestern Taiwan including the Kaoping River estuary, the Kaoping Canyon, Chiku and Tapong lagoons. Experimental results show that As and Hg in surface sediments from the Kaoping River estuary are mainly associated with mud (clay+silt) and TOC. They may also co-precipitate with Fe-Mn oxides/ hydroxides in sediments. Consequently, the seasonal variability of As and Hg distributions in estuarine sediments is likely attributed to the variations of particles size and TOC contents.
Distributions of As in surface sediments from the Kaoping Canyon are also related closely to mud, Fe-Mn oxides and TOC contents. The spatial variation of surface enrichment of As, however, is insignificant along the Kaoping Canyon. Concentrations of Hg in surface sediments are elevated around the river mouth and decrease seaward in the Kaoping Canyon. According to As and Hg distributions and accumulation rates in the Kaoping Canyon, pollution appears to increase significantly around 1970 corresponding to the period of economic boom in Taiwan.
With the exception of locations near the Chiku River and Daliao Creek, spatial distributions of As and Hg are largely determined by particle size, organic and Fe-Mn contents. In the Tapong Bay, concentrations and enrichments of As and Hg are generally higher in the inner bay than in the outer bay, primarily affected by distributions of particle size, organic and Fe-Mn contents. The enrichment of Hg in the inner bay appears to be enhanced by waste-water discharge, TOC accumulation and sulphide formation. The magnitudes of EF are larger in the Tapong Bay than in the Chiku Lagoon and the Kaoping River estuary for both As and Hg, indicating a higher pollution status in the Tapong Bay than in other areas.
Sequential extractions separate As and Hg into five fractions that can be roughly divided into mobile phase and non-mobile phase (residual fraction). The sum of mobile-like fractions is significantly correlated with the content extracted with 0.1M HCl. Arsenic and mercury speciation of sediments are quite similar in the Kaoping River estuary, the Chiku Lagoon and Tapong Bay. Both As and Hg are mostly concentrated in the residual fraction, and secondly located in Fe-Mn oxides for As, and in organic matter for Hg. Arsenic and mercury speciation in sediments are apparently not controlled by the variability of salinity in the estuary.
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Lin, Yen-Jou, and 林燕柔. "Urinary Levels of Arsenic and Mercury in Adults Living near a Coal-fired Power Plant." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/29725580265466591876.
Full textAbstract:
碩士<br>國立臺灣大學<br>職業醫學與工業衛生研究所<br>100<br>Background：Previous studies have shown coal-fired power plants emitted arsenic (As) and mercury (Hg) into environment but studies on the extent of human exposures to these pollutants in their surrounding areas are limited. This study aimed to use the biological markers of urine arsenic and mercury to evaluate adult’s exposures to As and Hg living near a big coal-power plant in Taiwan and identify personal and environmental factors associated with the exposures.
Methods：Based on wind direction and distance to a coal-fired power plant, our study areas includes two downwind high exposure areas (HE1 and HE2) within 5 km radius of the power plant, and a upwind low exposure area (LE2) outside the 5 km radius of the power plant. A total of 273 adults, aged 20 to 65 years, were randomly sampled from the HE and LE areas. Personal information and potential metal-related exposure factors were collected by questionnaire. The first morning urine specimen was collected twice form each person in 2009 and 2011, and the levels of urinary As and Hg were determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Ambient PM10 and PM2.5 were sampled by Harvard Impactor, and arsenic in PM10 was analyzed by ICP-MS. The bio-monitoring and ambient air sampling data in these different areas were compared by Student’s t test, ANOVA and ANCOVA. Multiple regressions were applied to determine difference in urine As and Hg among areas adjusting for personal factors.
Results：Among the 273 adults aged at 43.55±12.64 years that were in this study, there are 125 males and 148 females, and in 83 subjects in HE1, 115 subjects HE2 and 75 subjects in LE2. The geometric means of urinary As were 87.35 (2.58) μg/g creatinine in HE1, 65.48 (2.28) μg/g creatinine in HE2, and 57.28 (2.18) μg/g creatinine in LE2, respectively, for study subjects in 2011. The geometric means of urinary Hg were 1.78 (2.16) μg/g creatinine in HE1, 1.04 (2.05) μg/g creatinine in HE2, and 0.88 (2.04) μg/g creatinine in LE2, respectively. Urinary As and Hg levels in HE1 were significantly higher than those in LE2. Higher urinary As levels were associated with subject’s distance to power plant, age, length of residence, and lack of education. Higher Hg levels were associated with subject’s distance to the power plant, gemder (female), age, lower education, non-smoking status and consumption of local fish. After adjusted for those confounders by ANCOVA and multiple regression, levels of urinary As and Hg in HE1 were still significantly higher than those in HE2 and LE2. The concentrations of As in PM10 were 1.45±0.68 ng/m3 in HE1, 2.49±0.96 ng/m3 in HE2, 0.76±0.27 ng/m3 in LE2, respectively.
Conclusion：Adult residents living within 5 km radius of a coal-fired power plant had significantly higher urinary As and Hg concentrations than those living beyond 5 km radius.
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Pei-LingWong and 黃琲淩. "The association between Arsenic in well water and Parkinson's Disease in Taiwan." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/51555767877975094167.
Full textAbstract:
碩士<br>國立成功大學<br>環境醫學研究所<br>100<br>introduction: Parkinson's disease (PD) is the second most common progressive neurodegenerative disease in Taiwan. It is associated with the desecration of dopamine-generated neurons in the substantial nigra in the brain, but actual etiology remains unknown. Some animal studies found that arsenic can pass through the blood brain barrier, aggregate in the substantia nigra area, and inhibit the synthesis and release of dopamine. Therefore, exposure to arsenic may be related to the occurrence of PD, but few epidemiological data are available on this issue. We conduct a study to evaluate the association between arsenic exposure through drinking water and the occurrence of PD in Taiwan.
Methods: We used the National Health Insurance Research Database to identify patients with PD from 2005 to 2009 and defined cases as those who had ICD-9-CM codes 332.0 or 332.1 among the diagnoses and received prescription of medicine for PD. Arsenic exposure was assessed using the survey of well water in 243 villages conducted by the Taiwanese government. We compare the occurrence of PD between villages within and outside the endemic areas of arsenic exposure to evaluate the association between the arsenic level in drinking water and the PD after adjusting for gender and age.
Results: The prevalence of PD was 226/100,000 and the incidence of PD was 41.8/100,000. Men had higher prevalence than women, and the peak age of late-type PD was 70-80 years old. The relative risk of people living in the endemic areas of arsenic exposure was 1.4 compared to those who did not live in the areas, and the 95% confidence interval was 0.9-2.0, indicating a marginal statistical significance.
Conclusion: People living in the endemic areas of arsenic exposure from drinking water had a higher risk of developing PD, but the increase did not reach statistical significance.
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Yang, Hui-Erh, and 楊惠而. "Identification and characterization of a novel arsenic resistance transposon TnARS1 nested in a mercury resistance transposon TnMERI1." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/79502633040517508843.
Full textAbstract:
碩士<br>國立中興大學<br>生命科學系<br>93<br>The arsenic compounds are not merely abundant in the mineral deposit, but also are traced in the groundwater. In addition, these compounds has been widely applied to industry, agriculture, medical science and caused environmental pollution that needs to be solved. As regarding the arsenic toxicity, inorganic compounds are stronger than organic compounds. Among them, the toxicity of inorganic arsenite is greater than the inorganic arsenate. In the neutral and acid aqueous solution, the As(III) exists in the form of As(OH)3 that can be passed through the cell membrane transpoter by Aqua-glyceroporin family. The structure of inorganic arsenate compounds is similar to the phosphoric acid, so it competes with the biochemical role of phosphoric acid in the cell and causes the poison.
In our laboratory, some mercury resistance bacterial strains have been isolated from mercury-polluted sediment sample from Minamata Bay, Japan. One of these bacterial strains, designated as Bacillus species strain MB24, a 13.7 kb arsenic resistance transposon, TnARS1, was found nested in a mercury resistance transposon. This is the first discovery of an arsenic resistance transposon identified from Gram-positive bacteria. The TnARS1 harboring strain shows higher arsenic resistance level than other bacterial strain harboring without TnARS1. The annotation nucleotide sequence shows the gene cluster of arsenic resistance can be divided into two groups leading by the different regulatory genes, arsR1 and arsR2. The genetic structure of arsR2 cluster is arsR2-arsB-arsC-arsD-arsA. The cluster shows extremely high similarity to the arsenic resistance operon of plasmid pBc10987 which is harbored in Bacillus cereus ATCC 10987, while the open reading frames (ORF3, ORF4, ORF5) downstream the arsR1 gene do not show any similarity to known arsenic resistance related genes.
The ArsR1 contains not only the conserved arsenite binging site, but also possesses inverted repeats in font of the gene that may act as binding box for regulatory proteins. A plasmid pWParsR1 that contains O/P-arsR1 region and a promoterless protease gene (aprE) as reporter was constructed and transformed to a chromosomal arsR gene defected strain to show whether ArsR1 can be functional or not. Furthermore, arsR gene targeted real-time RT-PCR was performed to show the specificity of inducer.
Plasmids containing each gene cluster or both were transformed into a chromosomal arsB gene defected strain. The resistance level of arsenic was examined and showed that arsR1 gene cluster does not restore the arsenite resistance while both of the gene clusters are needed to restore the arsenite resistance. Though the actual role of ORF3, ORF4 and ORF5 remained unknown, their connection to arsenite resistance was shown in this study.
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Huang, Jun-Han, and 黃俊翰. "Study of atmospheric particle bound arsenic As(p), mercury Hg(p) concentrations and compositions in central Taiwan." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/55793674901427400809.
Full textAbstract:
碩士<br>弘光科技大學<br>環境工程研究所<br>99<br>This study investigated the ambient air particle bound arsenic As(p) and mercury Hg(p) compositions and concentrations in dry deposition and total suspended particulates (TSP) in central Taiwan during years of 2009-2010.
Bei-shi (suburban/coastal), Chang-hua (downtown), He-mei (residential), Quan-xing (industrial) and Gao-mei (wetland) sampling sites were selected in this study. The main industries at Quan-xing industrial park were steel industry, electronic industry, plastic industry and chemical industry. And the wetland was surrounded by Taichung thermal power plant (TTPP) and fossil fuel combustion. The main suburban/coastal were science park and fossil fuel combustion. And the downtown and residential were transportation, waste incineration, and fossil fuel combustion. The highest average concentrations seasonal variation for Hg(p) in TSP and dry deposition were occurred in spring at five characteristic sampling sites. The possible reason is due to the influence of dust storm from mainland China. In addition, the highest average concentrations seasonal variation of As(p) in TSP and dry deposition were occurred in fall and winter. The possible reason is that low-wind conditions brought elevated concentrations of As(p) in fall and winter at these five sampling sites. Finally, straw burning activities were prevailing in the months of September-October and January- February. In other words, fall and winter are the possible seasons for the high compositions in TSP and dry deposition of Hg(p) and As(p).
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Edwards, Alison. "Spatial and ecological patterns of mercury and arsenic concentrations in Pacific Ocean Perch (Sebastes alutus) from British Columbia." Thesis, 2011. http://hdl.handle.net/1828/3788.
Full textAbstract:
Pacific ocean perch (Sebastes alutus) is a slow growing species of demersal rockfish, which inhabits the continental slope of the west coast of North America. This species represents a highly commercial fishery and an important part of the groundfish fishery of British Columbia. A variety of biological factors are known to influence the concentrations of trace metals in fish, including, age, body size and diet; all of which vary in this species. Little is known of the concentrations of total mercury and total arsenic in Sebastes alutus from British Columbia, a Canadian province where marine groundfish have previously been found with elevated concentrations of mercury. The spatial variability of trace elements across different fishing regions within British Columbia is also unknown.
Substantial variability in concentrations of both mercury and arsenic has been reported in marine fish from around the globe. In the case of arsenic, associations between concentrations in muscle tissue and a variety of biological variables are not frequently reported. This contrasts with mercury, which is known to be intrinsically linked to the biology of fish. Consequently, biological variability in fish has the potential to confound studies of mercury and possibly arsenic in fish.
This thesis examines the influence of biological variables and fishing region on total mercury and total arsenic in Sebastes alutus from British Columbia. It also assesses the concentrations found in muscle tissue from a food safety perspective. Samples were obtained from a commercial fish processing plant on Vancouver Island and had been caught by a commercial fishing vessel in Hecate Strait, Queen Charlotte Sound and the west coast of Vancouver Island.
A multivariate outlier determination method was used to quantify the natural background variability across all three fishing regions. Significant differences in concentrations between regions were identified. This spatial variability of total arsenic did not appear to be related to age, body or body size. However, the spatial variability of mercury concentrations appear to be associated with the size and age of the fish sampled. The outlier determination procedure also identified the presence of elevated concentrations of both mercury and arsenic in specimens that were determined to be outliers. Outliers originated predominantly from the west coast of Vancouver Island and exceeded regulatory limits for both mercury and arsenic. In addition to the outliers, estimated quantities of MeHg frequently exceeded Provisional Tolerable Intakes for children and pregnant women.
Generalized Additive Models were produced to examine the effect of age, body size (length and mass) and diet (δ13C and δ15N) on concentrations of total mercury and total arsenic in Sebastes alutus within each fishing region. These identified significant nonlinear, qualitative patterns between mercury and body size in two out of three fishing regions. A significant nonlinear effect of age on arsenic concentrations was found. Model results also suggest an effect on arsenic concentrations of organic carbon sources; i.e., fish with stronger links to continental slope or inshore food webs (with relatively enriched δ13C signatures) had greater arsenic concentrations.<br>Graduate