Tesis: "Environmental chemistry. Persistent pollutants"

1

Johnsen, Ida Egge. "The Effect of Persistent Organic Pollutants on Thyroid Hormone Levels in Arctic Breeding Kittiwake (Rissa tridactyla)". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for biologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-13743.

Texto completo

Resumen

Black-legged kittiwakes (Rissa tridactyla) breeding in the Arctic, are exposed to annual fluctuating environmental conditions. The impact of inter-year variations in environmental conditions on the blood concentrations of persistent organic pollutants (POPs) was examined in black-legged kittiwakes breeding in Kongsfjorden, Svalbard. In addition, it was examined if inter-year variations in concentration of POPs were affecting circulating thyroid hormone (TH) levels. Blood samples were collected from breeding kittiwakes during the incubation period in 2008 (n=46) and 2009 (n=31), two different years in respect of environmental conditions. The whole blood samples were analyzed for POPs: polychlorinated biphenyls (PCBs; PCB-28, -52, -99, -118, -101, -138, -153, 180, -183, -187, -194), hexachlorobezene (HCB), hexachlorocyclohexan (HCH), dichlorodiphenyltrichloroethane (p,p’-DDT), dichlorodiphenyldichloroethylene (p,p’-DDE) oxychlordane, cis-chlordane, trans-chlordane, cis-nonachlor, trans-nonachlor, heptachlor, heptachloroepoxid, and mirex, using gas chromatography mass spectrometry. Plasma was analysed for concentrations of total triiodothyronine (T3), using radioimmunoassay. Associations between variables of POPs and T3 were analysed using univariate statistics. Biometric measurements of the kittiwakes; body mass, skull length, and wing length where included in the statistical analysis, together with calculated BC (BC; body mass controlled for body size). Associations between the variables were analysed using multivariate statistics. The PCBs were the dominant contaminants in both 2008 and 2009. The three major constituents in the kittiwakes were PCB-153, followed by PCB-138 and PCB-180. Even though the body condition of the kittiwakes was significant poorer in 2009 compared to 2008, the concentrations of PCBs and DDE did not differ between 2008 and 2009. The concentration (ng/g wet weight [w.w.]) of HCB and oxychlordane were significant higher in 2009 compared to 2008. There was a strong negative association between HCB and body condition of the kittiwakes. Also the concentration of oxychlordane was negative correlated to body condition. Thus, kittiwakes with poor body condition had higher levels of HCB and oxychlordane. Additionally, HCB, oxychlordane and PCB-183 were positively associated with egg-laying date, while body condition was negatively correlated to egg-laying date. The results showed that kittiwakes with a poor body condition and thus, high levels of HCB and oxychlordane, were associated with late breeding. The low body condition in 2009 indicated poor food availability and unfavourable conditions for the kittiwakes that year.

Los estilos APA, Harvard, Vancouver, ISO, etc.

2

Hansen, Ingunn Tjelta. "Effects of Persistent Organic Pollutants on Reproductive Hormones in Male Polar Bears (Ursus Maritimus) from Svalbard". Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for biologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-16822.

Texto completo

Resumen

PCBs and other environmental contaminants have been found to have an effect on steroid hormones in polar bears (Ursus maritimus). The purpose of this study was to investigate the effect of persistent organic pollutants (POPs) on the steroidogenesis in male polar bears from Svalbard. Blood samples from male polar bears (n=23) were collected at Svalbard, Norway in April 2008 as a part of the International Polar Year-project, BearHealth. The sampled individuals were between 3-21 years, where individuals under 5 years (n=6) were categorized as subadults. Serum and plasma samples were analysed for steroid hormones (pregnenolone (Pre), progesterone (Pro), androstenedione (AN), dehydroepiandrosterone (DEA), testosterone (TS), dihydrotestosterone (DHT), estrone (E1), estradiol-17α (E2-α) and estradiol-17β (E2-β)) with a recently developed gas chromatography-tandem mass spectrometry (GC-MS/MS) determination method, whereas cholesterol concentrations were measured by Reflotron. The environmental contaminants (HCB, α‐HCH, β‐HCH, oxychlordane, trans‐nonachlor, mirex, p,p'-DDE, p,p'‐DDT, PCB‐47, PCB‐74, PCB‐99, PCB‐101, PCB‐128, PCB‐137, PCB-138, PCB‐153, PCB‐170, PCB‐180, PCB‐183, PCB‐187, PCB‐194, PCB‐206, PCB-105, PCB-114, PCB-118, PCB-156, PCB-157, PCB-167, PCB-189, 4'-OH-CB107, 4'-OH-CB130, 3'-OH - CB138, 4‐OH‐CB146, 4'-OH‐CB159, 4'-OH-CB172, 3'-OH-CB180, 4-OH‐CB187, BDE-47, BDE-154) included in this study were analysed by gas chromatography-electron capture detection (GC-ECD) or GC/MS. Multivariate regression analysis, principal component analysis (PCA) and orthogonal partial least squares (OPLS) regression, were performed to investigate the influence of the contaminants on the steroid hormones in the adult individuals. Only the OPLS model with DHT as the response variable was significant. Most of the environmental contaminants had a significantly negative contribution on the variation in dihydrotestosterone concentrations. Based on the statistical analyses, the poly-ortho PCBs and HCB might be more central in explaining the variation in DHT concentrations, while PBDEs and OH-PCBs seems to be less important. Androstenedione were found to be the androgen with highest concentration in circulating blood from male polar bears, unlike other studies on mammals where testosterone has been found to be the most abundant androgen. The high level of AN might be connected to the negative effect of contaminants on DEA levels. The GC-MS/MS method applied in the current study can successfully compete with other frequently used determinations methods, such as RIA. The method is appropriate for the study several steroid hormones and their precursors in male polar bears and can be recommended for studies investigating the effect of persistent organic pollutants on the on the steroidogenesis.

Los estilos APA, Harvard, Vancouver, ISO, etc.

3

Weiss, Jana. "Human exposure to persistent organic pollutants : Illustrated by four case studies in Europe". Doctoral thesis, Stockholm : Department of Environmental Chemistry, Stockholm University, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-1057.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

4

Persson, N. Johan. "Models of the Distribution of Persistent Organic Pollutants in the Marine Environment". Doctoral thesis, Stockholm : Univ, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-11.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

5

Newsome, Bradley J. "Addressing Public Health Risks of Persistent Pollutants Through Nutritional Modulation and Biomimetic Nanocomposite Remediation Platforms". UKnowledge, 2014. http://uknowledge.uky.edu/chemistry_etds/38.

Texto completo

Resumen

Due to their relative chemical stability and ubiquity in the environment, chlorinated organic contaminants such as polychlorinated biphenyls (PCBs) pose significant health risks and enduring remediation challenges. Engineered nanoparticles (NPs) provide a novel platform for sensing/remediation of these toxicants, in addition to the growing use of NPs in many industrial and biomedical applications, but there remains concern for their potential long-term health effects. Research highlighted herein also represents a transdisciplinary approach to address human health challenges associated with exposure to PCBs and NPs. The objectives of this dissertation research are two-fold, 1) to develop effective methods for capture/sensing and remediation of environmental toxicants, and 2) to better understand associated risks and to elucidate relevant protective mechanisms, such as lifestyle-related modulators of environmental disease. Prevalent engineered nanoparticles, including aluminum oxide and titanium dioxide, have been studied to better understand effective nanoparticle dispersion methods for in vitro nanotoxicology studies. This work has served both to effectively stabilize these nanoparticles under physiological conditions and to better understand the associated mechanisms of toxicity, which links these metal nanoparticles to endothelial oxidative stress and inflammation through phosphorylation of key cellular signaling molecules and increased DNA binding of pro-inflammatory NFκB. Surface functionalization, though, is being found to limit potential toxicity and has been utilized in subsequent research. A novel polyphenol-functionalized, NP-based system has been developed which combines the biomimetic binding capabilities of nutrient polyphenols with the separation and heating capabilities of superparamagnetic iron oxide NPs for the capture/sensing of organic contaminants in polluted water sources. Magnetic nanocomposite microparticles (MNMs) incorporating the fluorescent polyphenols quercetin and curcumin exhibit high affinity for model organic pollutants followed by rapid magnetic separation, addressing the need for sustainable pollutant remediation. Further work has been performed to both better understand health concerns associated with environmental toxicants such as PCBs and to determine effective methods for modulating their toxicity. This research has shown that PCB remediation through dechlorination is a viable technique for decreasing endothelial inflammation, although complete dechlorination to biphenyl is necessary to effectively eliminate superoxide production, NFκB activation, and induction of inflammatory markers. Additionally, the nutrient polyphenol EGCG, found in green tea, has been shown to serve as a biomedical modulator of in vivo PCB toxicity by up-regulating a battery of antioxidant enzymes transcriptionally controlled by AhR and Nrf2 proteins.

Los estilos APA, Harvard, Vancouver, ISO, etc.

6

Garí, de Barbarà Mercè 1982. "Patterns of accumulation of persistent organic pollutants in human populations". Doctoral thesis, Universitat Pompeu Fabra, 2013. http://hdl.handle.net/10803/132809.

Texto completo

Resumen

The present research explores the levels and patterns of accumulation of a wide range of persistent organic pollutants (POPs) in the human population. It assesses two major families of POPs, namely organochlorine compounds (OCs) and polybrominated diphenyl ethers (PBDEs), and focuses on the population of Catalonia, a Mediterranean country in South-West Europe with active agricultural and industrial sectors. The research described in this study is based on a public health survey conducted by the Government of Catalonia in 2002, which included a health exam and a blood testing for 919 individuals. Gas chromatography and mass spectrometry techniques have been used to determine the concentrations of these pollutants in the serum samples. This research has customised a methodology to better detect organochlorine compounds in human serum samples. It has also contrasted the POP concentrations with a set of socio-demographic factors, with a special focus on age, sex and body mass index (BMI). And nally, it provides complementary assessments on POPs in other locations of Catalonia, including the Flix township that hosts a chemical factory; and on mercury, which is a non-organic persistent pollutant, in the infant population of the Menorca island. In essence, this research navigates in a diversity of pollutants, research methodologies and geographic conditions to explore the linkages between environmental pollution and human health.
Aquest estudi avalua els nivells i els patrons d'acumulació d'un ampli ventall de contaminants orgànics persistents (COPs) en la població humana. Comprèn dues classes de COPs, específicament els compos- tos organoclorats (OCs) i els polibromodifenil eters (PBDEs), i se centra en la població de Catalunya, un país mediterrani del sud-oest d'Europa amb uns sectors agrícola i industrial actius. La recerca descrita en aquest estudi es basa en una enquesta de salut pública duta a terme per la Generalitat de Catalunya el 2002, que va incloure en examen de salut i l'extracció d'una mostra de sang per a 919 persones. Les concentracions d'aquests contaminants en les mostres de s erum es van determinat mitjan cant t ecniques de cromatogra a de gasos i espectrometria de masses. En aquesta recerca s'ha dissenyat una metodologia específica per tal de millorar la detecció dels compostos organoclorats en mostres de sèrum humà. A més, les concentracions de COPs s'han contrastat amb una sèrie de factors sòcio-demogràfics, amb una especial atenció al sexe, l'edat i l' índex de massa corporal (IMC). Finalment, l'estudi proporciona avaluacions complementàries sobre els COPs en altres llocs de Catalunya, incloent el municipi de Flix, que acull una fàabrica de productes químics; i sobre el mercuri, un contaminant persistent inorgànic, a la població infantil de l'illa de Menorca. En resum, aquesta recerca combina una diversitat de contaminants, mètodes analítics i àrees geogrà ques per tal d'explorar l'associació entre la contaminació medioambiental i la salut humana.

Los estilos APA, Harvard, Vancouver, ISO, etc.

7

Strid, Anna. "Organohalogen contaminants in Greenland shark (Somniosus microcephalus)". Doctoral thesis, Stockholms universitet, Institutionen för material- och miljökemi (MMK), 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-45828.

Texto completo

Resumen

The remote sub-Arctic/Arctic environment has due to human activities become a sink for organohalogen contaminants (OHCs). These OHC include traditional contaminants such as polychlorinated biphenyls (PCBs), DDTs and technical mixtures of polybrominated diphenyl ethers (PBDEs), all included in the Stockholm Convention list of persistent organic pollutants (POPs). Other OHCs, currently under evaluation to be included among the POPs i.e. short chain chlorinated paraffins (SCCPs) and hexabromocyclododecane (HBCDD) are also found in these environments as well as a whole range of other OHCs. The main objective of this thesis is to increase the knowledge about the presence of OHCs in a high trophic Arctic shark species, the Greenland shark (Somniosus microcephalus). The Greenland shark is an opportunistic feeder, occasionally feeding at the top of the Arctic marine food chain. Furthermore may this species have a life span in excess of 100 years and is probably among the oldest of any fish species. These traits make the shark prone to accumulate elevated concentrations of OHCs. This has shown to be true for the Greenland sharks studied and most of the targeted OHCs were determined in the species. The highest concentrations were observed for the DDTs, ranging up to 26 μg/g fat. Other OHCs reported that are of special interest are SCCPs and brominated flame retardants used as replacement products to PBDEs; pentabromoethylbenzene (PBEB) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE). Also a range of OHCs whose origin is assumed to be natural, were shown to be present in Greenland sharks. This thesis is stressing the fact that even though the use of certain OHCs has been banned for decades they are still present at high concentrations in the deep waters of the Arctic. Therefore it is of major importance to continue to monitor the fate of traditional and emerging OHCs in the environment, and for this purpose the Greenland shark is an excellent species.
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

Los estilos APA, Harvard, Vancouver, ISO, etc.

8

Betson, Tatiana. "Deuterium isotopomers as a tool in environmental research". Doctoral thesis, Umeå : Univ, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-938.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

9

Yang, Congqiao. "Persistent organic pollutants in lacustrine environments". Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/5030/.

Texto completo

Resumen

Water samples taken from nine English freshwater lakes from a mix of urban, rural, and remote locations on 13 occasions between April 2008 and February 2012 were analysed for selected non-dioxin like-PCBs, tri- through hexa-PBDEs, and the three main HBCD diastereomers (\(\alpha\)-, \(\beta\)-, and \(\gamma\)-HBCD). Concentrations of PCBs and HBCDs declined over the sampling period with half-lives of 3.8 and 5.1 years, respectively. In addition, concentrations of PCBs, HBCDs, tri- through deca-BDEs, and 32 selected NBFRs were measured in radiometrically-dated sediment core slices taken in summer 2011/2 from seven of the same English lakes. Temporal trends in contamination with “legacy” POPs generally accord with historical trends in UK manufacture and use, with PCB contamination at all lakes increasing from ~1950, peaking generally between the late-1960s and mid-1980s, before declining steadily thereafter. In contrast, at most sites, BDE-209 displayed generally smooth increases following its initial emergence, and showed no obvious levelling off trend. Contamination with some NBFRs displayed significantly increasing trends. Spatial variation in POPs contamination of the lakes studied was evident; with regression analysis suggesting concentrations are higher in lakes with surface areas that are small relative to their catchment area, and that are closer to areas of high population density. The estimated PCB burden in the British environment is 521 tons, with TBPH (281 tons) and BDE-209 (147 tons) following not far behind. Estimated UK burdens of the remaining target compounds were significantly lower.

Los estilos APA, Harvard, Vancouver, ISO, etc.

10

Wiberg, Karin. "Enantiospecific Analysis and Environmental Behavior of Chiral Persistent Organic Pollutants (POPs)". Doctoral thesis, Umeå universitet, Kemiska institutionen, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-9.

Texto completo

Resumen

Many persistent organic pollutants (POPs) are chiral. These pollutants are generally released into the environment as racemates, but frequently undergo alterations in enantiomeric composition as soon as they are subjected to life chemistry processes. Enantiospecific analysis of chiral POPs is important since enantiomers of chiral compounds often exhibit differences in biological activity, and most biochemical processes in nature are stereospecific. For abiotic processes, such as air-water gas exchange, deposition and long-range air transport, enantiomeric patterns of POPs may be used as chemical markers. The aim of the work described in this thesis was to improve our knowledge about the presence and fate of enantiomers of chiral POPs inthe environment to provide a sound basis for accurate risk assessment. The compounds included were organochlorine (OC) pesticides (α-HCH, chlordanes and o,p’-DDT), atropisomeric PCBs and some of their respective metabolites (heptachlor-exo-epoxide, oxychlordane and MeSO2-PCBs). Analytical methods for chiral PCBs were developed, and the elution sequences of (+) and (−)-enantiomers were determined. Enantiomeric fraction (EF) was proposed as a better reflector of chiral composition than the conventional enantiomeric ratio (ER). Enantioselective bioprocessing in various compartments was studied, with the main emphasis on factors controlling chiral composition in biota Correlations were detected between changes in EFs and differences in trophic levels. The changes were, however, not consistent for all compounds. Instead, the enantiomeric composition was found to be species-specific in the polar bear food chain and in aquatic species from the Baltic Sea. The EFs of some POPs in Baltic seals were related tonutritional status and biotransformation capacity. Enantiomeric and isomeric patterns were used to investigate abiotic processes in the southern Baltic Sea environment and EFs were used tostudy soil as a source of atmospheric heptachlor-exo-epoxide.

Los estilos APA, Harvard, Vancouver, ISO, etc.

11

Paul, Alexander George. "Modelling the sources, fate and environmental behaviour of persistent organic pollutants". Thesis, Lancaster University, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618814.

Texto completo

Resumen

This thesis attempts to logically follow the full lifecycle of a 'new' persistent organic pollutant (POP), perfluorooctane sulfonate (PFOS). A new estimate of the global historical production for perfluorooctane sulfonyl fluoride (POSF) was produced, before focusing on deriving the first estimate of the global historical environmental releases of PFOS. The total historical worldwide production of POSF was estimated to be 96,000 tonnes between 1970- 2002, with an estimated global release of 45,250 t to air and water between 1970-2012. Estimates indicated POSF-derived products are the major direct source of PFOS emissions, resulting in an estimated release of 450-2700 t into wastew31er streams over the same period. Due to the physiochemical properties of PFOS (soluble in water, negligible vapour pressure, and limited sorption to particles), emissions from consumer products including stain repellent treated fabrics, waterproof apparel, and aqueous fire fighting foams were expected to be largely to waste water. The following papers saw two existing multi-media environmental fate models reparameterised to explore the role of emissions from diffuse consumer use. PFOS emissions were linked to waste water treatment plants, partitioning and emissions uncertainty were explored, and annual fluxes of PFOS were estimated from European rivers at a local and continental scale. A good agreement, generally within a factor of three between modelled emissions derived from population density and measured freshwater PFOS concentrations, was observed. The final paper is a slight departure from the others submitted in this thesis. This paper returns to 'classical' POPs, but looks forward in time to try and understand the potential impact of climate change on POP chemicals. Overall. predicted changes were small even under the most conservative scenarios, resulting in slightly increased volatilisation and degradation in air from a drier and warmer south-western Europe, corresponding to a transfer and redeposition of POPs to the cooler and wetter north-eastern Europe.

Los estilos APA, Harvard, Vancouver, ISO, etc.

12

Lau, Hoi-yin Melody y 劉凱賢. "Environmental impacts and management of persistent organic pollutants in South China". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43783867.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

13

Lau, Hoi-yin Melody. "Environmental impacts and management of persistent organic pollutants in South China". Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B43783867.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

14

Mweetwa, Alice Mutiti. "An Inventory of Agricultural Persistent Organic Pollutants in Lusaka, Zambia". Miami University / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=miami1084968977.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

15

Rahman, Qazi Mousumi. "Immunohepatotoxicity of the persistent environmental pollutants perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS)". Doctoral thesis, Stockholms universitet, Institutionen för biokemi och biofysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-63180.

Texto completo

Resumen

Perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS), manufactured for a variety of industrial and consumer applications, are ubiquitous environmental pollutants. Their accumulation in humans and wildlife raises serious health concerns. Here, we examined the potential effects of PFOA and PFOS on the innate immune system in mice. Short-term dietary exposure to high doses reduces the total number and subpopulations of circulating white blood cells. Moreover, production of proinflammatory cytokines by macrophages in the peritoneal cavity and bone marrow, but not in the spleen following exposure to in vitro or in vivo stimulation by bacterial lipopolysaccharides is enhanced. With respect to adaptive immunity, PFOS reduces the total numbers of thymocytes and splenocytes and subpopulations thereof in a dose dependent fashion. Furthermore, comparison of wild-type mice and the corresponding knock-out strain lacking peroxisome proliferator-activated receptor-alpha revealed that these immunological changes are partially dependent on this receptor. Our further studies also show that sub-chronic dietary exposure to an environmentally relevant dose of PFOS does not alter the cellularity of the thymus and spleen and exerts no influence on humoral immune responses. To facilitate examination of the effects of PFOA and PFOS on the hepatic immune system, we developed a procedure for mechanical disruption that yields a larger number of functionally competent immune cells from this organ. In our last study, lower doses of PFOA or PFOS induced hypertrophy of hepatocytes and altered the hepatic immune status. Thus, we find that short-term, high- and low-dose exposure of mice to these fluorochemicals is immunohepatotoxic.
Perfluorooktanat (PFOA) och perfluorooktansulfonat (PFOS) som tillverkas för många olika industri och konsumentprodukter, är globalt förekommande miljögifter. Deras ackumulering i människor och djur ger upphov till en stark oro för hälsoproblem. Vi har granskat effekterna av PFOA och PFOS på det medfödda, ospecifika immunförsvaret. Exponering för höga doser via maten under kort tid minskar det totala antalet cirkulerande vita blodkroppar samt delpopulationerna.. Immunsvaret ökar dock efter stimulering med bakteriella lipopolysaccharider både in vitro och in vivo , dvs produktionen av proinflammatoriska cytokiner av makrofager i bukhålan och benmärgen, men inte i mjälten ökar.. När det gäller adaptiv, specifik immunitet minskar PFOS det totala antalet tymocyter och splenocyter och deras olika subpopulationer. Vid exponering för lägre doser av PFOS induceras hepatomegali utan att påverka tymus eller mjälten. Vi kunde visa att peroxisomal proliferator-aktiverad receptor-alfa medierar effekterna utav PFOS i tymus samt delar av effekterna av PFOS i mjälten genom att använda möss som saknade denna receptor. . Dettastöds av vår studie med subkronisk exponering för en miljömässig dos av PFOS vilken inte ändrade den cellulära sammansättningen i vare sig tymus eller mjälte och inte hade något inflytande på det humorala immunsvaret. För att underlätta studier av hur PFOA och PFOS påverkar immunsystemet i levern utvecklade vi en metod för framrening av immunceller via mekanisk sönderdelning av levern, vilket gavett större antal av funktionella immunceller från detta organ. I vår sista studie kunde vi påvisa att lägre doser av PFOA eller PFOS inducerade hypertrofi av hepatocyter samt en påverkan av leverns immunförsvar.

Los estilos APA, Harvard, Vancouver, ISO, etc.

16

Brister, Matthew Michael. "PHOTOCHEMISTRY OF NUCLEIC ACIDS AND ENVIRONMENTAL POLLUTANTS". Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1523021339182475.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

17

Hafner, William D. "Source apportionment and atmospheric transport of persistent organic pollutants near the Great Lakes". [Bloomington, Ind.] : Indiana University, 2005. http://wwwlib.umi.com/dissertations/fullcit/3162972.

Texto completo

Resumen

Thesis (Ph.D.)--Indiana University, School of Public Environmental Affairs, 2005.
Title from PDF t.p. (viewed Dec. 2, 2008). Source: Dissertation Abstracts International, Volume: 66-02, Section: B, page: 0785. Chair: Ronald A. Hites.

Los estilos APA, Harvard, Vancouver, ISO, etc.

18

Chiuchiolo, Amy Lee. "Persistent Organic Pollutants at the Base of the Antarctic Marine Food Web". W&M ScholarWorks, 2003. https://scholarworks.wm.edu/etd/1539617810.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

19

Tsang, Hin Long. "Persistent organic pollutants in foodstuffs and human samples from Hong Kong". HKBU Institutional Repository, 2008. http://repository.hkbu.edu.hk/etd_ra/873.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

20

Geisz, Heidi N. C. "Persistent Organic Pollutants(POPs) as Tracers of Environmental Change and Antarctic Seabird Ecology". W&M ScholarWorks, 2010. https://scholarworks.wm.edu/etd/1539616664.

Texto completo

Resumen

Antarctic seabirds including Adelie penguins (Pygoscelis adeliae), south polar skuas (Catharacta maccormicki), southern giant petrels (Macronectes gigantus) are high trophic level predators that accumulate persistent organic pollutants (POPs) present in the food webs in which they forage. Little is known about the levels of POPs in some Antarctic organisms (e.g. southern giant petrels), as well as the long-term trends of POPs in the Antarctic ecosystem. Samples from all three seabird species were collected post mortem, including eggs, from the Western Antarctic Peninsula (WAP) and in the Ross Sea throughout the austral summer breeding seasons of 2004--2006. The samples were analyzed for C and N stable isotopes and POPs including organochlorine pesticides, polychlorinated biphenyls (PCBs), and brominated diphenyl ethers (BDEs). The objectives of this study were to: (1) evaluate the long-term trends of POP residues in Adelie penguins, (2) compare POP levels within livers of the three seabird species based on migratory patterns and trophic level using stable isotope analysis of delta15N and delta13C, and (3) demonstrate POPs can be used as tracers of Antarctic seabird ecology. POPs in Antarctic biota were first evaluated using Adelie penguin tissues and a long-term analysis including data from the current study showed SigmaDDT has not declined in WAP penguins for more than 30 years. Indeed, the presence of p,p'-DDT in these birds indicates that there is a current source of DDT to the WAP marine food web, and both measurements and calculations suggest that this source of DDT is related to climate driven environmental change in the region. A more broad analysis including all three seabird species showed SigmaPCBs, SigmaDDTs, Sigmachlordanes and mirex are 3--100 times higher in migratory seabird livers than the endemic penguins, while hexachlorobenzene (HCB) exhibits no difference in concentration between the three seabird species. Model predictions compared to measured output of delta13C and delta13N indicate a stronger correlation between delta13C and less volatile POP concentrations demonstrating the heavy influence of winter migration on the contaminant loads of seabirds that breed in Antarctica. Finally, discrepancies in POP ratios between migratory and endemic seabird eggs and fat in combination with stable isotope signatures gave insight into seabird evolutionary breeding strategies. For example, the relative abundance of SigmaPCBs was highest in south polar skua eggs and endogenous lipid input into skua eggs was estimated at >79% by examining discrepancies in contaminant ratios. The combined stable isotope and contaminant data indicate that south polar skuas and southern giant petrels employee different combinations of income and capital breeding strategies.

Los estilos APA, Harvard, Vancouver, ISO, etc.

21

Pike-Thackray, Colin Michael. "An uncertainty-focused approach to modeling the atmospheric chemistry of persistent organic pollutants". Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/107106.

Texto completo

Resumen

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2016.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 103-109).
In this thesis, I study polycyclic aromatic hydrocarbons (PAHs) and perfluorocarboxylic acids (PFCAs). PAHs are by-products of burning and therefore have important anthropogenic sources in the combustion of fuels, biomass, etc. PFCAs and their atmospheric precursors are used in making firefighting foams, non-stick coatings, and other surfactant applications. I quantitatively examine the relative importance of uncertainty in emissions and physicochemical properties (including reaction rate constants) to Northern Hemisphere (NH) and Arctic PAH concentrations. NH average concentrations are more sensitive to uncertainty in the atmospheric lifetime than to emissions rate. The largest uncertainty reductions would come from precise experimental determination of PHE, PYR and BaP rate constants for the reaction with OH. I calculate long-chain PFCA formation theoretical maximum yields for the degradation of precursor species at a representative sample of atmospheric conditions from a three dimensional chemical transport model, finding that atmospheric conditions farther from pollution sources have both higher capacities to form long chain PFCAs and higher uncertainties in those capacities. I present results from newly developed simulations of atmospheric PFCA formation and fate using the chemical transport model GEOS-Chem, simulating the degradation of fluorotelomer precursors, as well as deposition and transport of the precursors, intermediates and end-products of the PFCA formation chemistry. I compare the model results to remote deposition measurements and find that it reproduces Arctic deposition of PFOA effectively. Given the most recent precursor emission inventory, the atmospheric indirect source of PFOA and PFNA is 10-45 t/yr globally and 0.2-0.7 t/yr to the Arctic.
by Colin Michael Pike-Thackray.
Ph. D.

Los estilos APA, Harvard, Vancouver, ISO, etc.

22

Clarke, Bradley y Bradley clarke@student rmit edu au. "Persistent Organic Pollutants in Australian Sewage Sludge: Environmental Monitoring and Land Application Risk Assessment". RMIT University. Applied Sciences, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20081202.113842.

Texto completo

Resumen

Presented is a study of persistent organic pollutants in Australian sewage sludge, focusing on environmental monitoring and a sewage sludge land application human health risk contaminated with these compounds. The chemicals of concern were: Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and

Los estilos APA, Harvard, Vancouver, ISO, etc.

23

Krop, Hildo Boudewijn. "Thermodynamic approaches for the environmental chemistry of organic pollutants". [Amsterdam] : Amsterdam : Universiteit van Amsterdam ; Universiteit van Amsterdam [Host], 2003. http://dare.uva.nl/document/87599.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

24

Gokmen, Pinar. "Evaluation Of Persistent Organic Pollutants (pops) In Balikesir Dam Lake Sediments". Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12612916/index.pdf.

Texto completo

Resumen

In this study, the Persistent Organic Pollutants (POPs) specifically
17 Organochlorine Pesticides (OCPs) and 19 Polycyclic Aromatic Hydrocarbons (PAHs) were evaluated in the sediment samples of Balikesir (Ikizcetepeler) Dam Lake. Sixteen sampling points were chosen for determination of concentrations of OCPs and PAHs After ultrasonic bath extraction of the sediment samples GC-MS was used as analytical tool. Extraction efficiencies changes from 63.8 to 87.4% depending on the type of the POPs. Average OCP concentration was found in the range of 3.33-379 µ
g/kg a, average PAH concentration was found in the range of 3.28-32.9 µ
g/kg. Pollution maps regarding OCP and PAH distributions were drawn and the correlation between these two pollutant types was investigated. The quality control (QC) and quality assurance tests were applied by the analysis of standard reference materials (SRMs), surrogate standards and analysis replicates.

Los estilos APA, Harvard, Vancouver, ISO, etc.

25

Templeton, Jessica. "Framing elite policy discourse : science and the Stockholm Convention on Persistent Organic Pollutants". Thesis, London School of Economics and Political Science (University of London), 2011. http://etheses.lse.ac.uk/361/.

Texto completo

Resumen

Rising levels of persistent organic pollutants (POPs) in the environment have spurred governments around the world to engage in cooperative action on a global scale to control those chemicals that pose significant threats to human health and the environment. Political efforts to mitigate the risks posed by these chemicals are impeded by the technical complexity associated with POPs pollution, and are thus predicated on the scientific assessments of experts in fields such as chemistry and toxicology. Policymakers’ reliance on scientific expertise for guidance on risk assessment and management has reduced their control over policy and has given scientists authority to determine socially acceptable levels of risk, thus blurring the boundaries between science and politics. Conversely, the implications of science-based decision-making have increased the interest and involvement of political actors in a phase of evaluation that is often seen as objective, fact-based, and free of political interest. This thesis analyzes the ways in which various actors with scientific expertise – representatives of governments, industry, and environmental/public health NGOs – working under the auspices of the Stockholm Convention on Persistent Organic Pollutants have used strategic issue framing tactics to promote predetermined policy agendas during the scientific review of chemicals proposed for regulation. This research breaks new ground by analyzing the ways elite decision-makers strategically frame issues in order to influence the policy preferences of other elites, and by evaluating the role of issue framing in the context of live policy negotiations. Key findings include the following: 1) the formation of epistemic communities of technical experts is precluded by political pressure on scientists to represent government/organizational interests, and 2) scientists strategically frame issues in ways that support the social, economic or political interests of the governments or organizations with which they are affiliated, thus contributing to the politicization of science-based decision-making.

Los estilos APA, Harvard, Vancouver, ISO, etc.

26

Lundstedt-Enkel, Katrin. "QSBMR Quantitative Structure Biomagnification Relationships : Studies Regarding Persistent Environmental Pollutants in the Baltic Sea Biota". Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-6173.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

27

Prevedouros, Konstantinos. "Modelling the fate and environmental distribution of persistent organic pollutants at the local and regional scale". Thesis, Lancaster University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.421813.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

28

Raff, Jonathan Daniel. "Transport of organic pollutants and their atmospheric fates". [Bloomington, Ind.] : Indiana University, 2007. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3292440.

Texto completo

Resumen

Thesis (Ph. D.)--Indiana University, School of Public and Environmental Affairs, 2007.
Title from dissertation home page (viewed May 28, 2008). Source: Dissertation Abstracts International, Volume: 68-11, Section: B, page: 7189. Adviser: Ronald A. Hites.

Los estilos APA, Harvard, Vancouver, ISO, etc.

29

Basile, Emily Rose Avery Harold W. "Persistent organic pollutants in diamondback terrapin (Malaclemys terrapin) tissues and eggs, and sediments in Barnegat Bay, New Jersey /". Philadelphia, Pa. : Drexel University, 2010. http://hdl.handle.net/1860/3309.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

30

Annarapu, Shashidhar. "Thermal Analysis of Binding of Organic Pollutants to Titanium Dioxide". TopSCHOLAR®, 2014. http://digitalcommons.wku.edu/theses/1338.

Texto completo

Resumen

Conventional waste water treatment processes are not completely effective in removing highly stable organic compounds. Photocatalytic degradation on titanium dioxide is a possible alternative technique for many classes of these compounds. Several studies have been done by other researchers to study mechanisms of photocatalytic degradation, which occurs either through direct oxidation by holes or via indirect oxidation by radical messengers. Titanium dioxide can oxidize substrates directly through hole oxidation mechanisms or indirectly through free radical mechanisms. Substrates must bind onto the catalyst surface to undergo direct oxidation by holes. Thermogravimetric analysis (TGA) was performed on four different classes of compounds; iodinated contrast agents (iohexol and diatrizoate), polycyclic aromatic hydrocarbons (perylene and pyrene), the antibacterial agent triclosan and the pesticide atrazine, to investigate which of the compounds are adsorbed on the surface of titanium dioxide to undergo direct oxidation through electron holes. Differential scanning calorimetry (DSC) was conducted on triclosan and atrazine to determine if the desorption reaction is endothermic or exothermic. Powder X-ray diffraction was performed on all four classes of compounds to observe diffraction pattern of these compounds.

Los estilos APA, Harvard, Vancouver, ISO, etc.

31

Desborough, Jennifer L. "Exploring the utility of chiral signatures to further understanding of soil-to-herbage transfer of Persistent Organic Pollutants (POPs)". Thesis, University of Birmingham, 2012. http://etheses.bham.ac.uk//id/eprint/3537/.

Texto completo

Resumen

Chiral signatures were utilised as a means of determining the pathways of PCBs in the environment. Concentrations of HBCD diastereoisomers, enantiomers and degradation products were also determined in top soils from both the UK and Australia. Concentrations of PCBs 28/31, 52, 101, 118, 138, 153, and 180 and enantiomer fractions (EFs) of PCB 95 and 136 were determined in air, top soil and grass from an urban site in Birmingham, UK. Samples were taken approximately every 14 days at 5 graduating heights from the ground in summer 2009 (114 days) and spring 2010 (84 days). EFs of PCB 95 in air at 3cm height (average of 0.453 in 2009 and 0.468 in 2010), differed significantly (p<0.05) from the racemic EFs in air at 10, 40, 90, and 130 cm. The EFs of PCB 95 in soil were on average 0.452 in 2009 and 0.447 in 2010 and matched those in air at 3cm particularly in the 2009 campaign. Grass displayed an average EF of 0.468 (2009) and 0.484 (2010); values which were intermediate between those in soil and the racemic EFs in air measured at 10 cm and above. These data imply that at the study site, PCBs volatilise from soil to an extent discernible only at the soil:air interface, and that PCBs in grass arise due to foliar uptake of volatile emissions from soil. Atmospheric concentrations of PCBs increased significantly (p<0.05) with increasing height above the soil surface. This combined with the PCB 95 chiral signature data, suggests that the influence of PCB emissions from soil on airborne concentrations decreases with height while emissions from indoor air increases. HBCD chiral signatures were found to be racemic or near-racemic in all the air, grass and soil samples from the same urban site in Birmingham, UK used for sampling PCBs. Soils from 24 ii sites across the UK were also found to contain near racemic chiral signatures of HBCDs. This indicates that enantioselective microbial degradation is not occurring and the sites were unsuitable for a study like that used for PCBs to determine pathways of HBCDs into plants using chiral signatures. Concentrations of ΣHBCD from soils from the UK (n=24) were found to be 22 ng/g ranging between <0.03 to 420 ng/g. By comparison, the average concentration of ΣHBCD in soils from Australia (n=17) was 0.74 ng/g ranging between <0.0005 to 5.6 ng/g. Degradation products of HBCD, pentabromocyclododecenes (PBCDs) and tetrabromocyclododecadienes (TBCDs) were also semi-quantitatively determined in the soil samples. In the UK soils, PBCDs and TBCDs were determined in 7 and 6 of the soil samples respectively with concentrations ranging from 10-7300 pg/g for ΣPBCDs and 10-1300 pg/g for ΣTBCDs. In the Australian soils only TBCD was detected in soil at concentrations ranging from 2.3 to 450 pg/g ΣTBCDs. A preliminary environmental budget found soil to be the principal sink for HBCD in the UK.

Los estilos APA, Harvard, Vancouver, ISO, etc.

32

Howard, Angela L. "Strategies for the analytical determination of thermally labile sulfur-containing environmental pollutants". Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/39291.

Texto completo

Resumen

Increasing public awareness of toxic moieties in our environment has put pressure on regulatory agencies to improve testing methods so that these harmful agents can be identified and quantitated at lower and lower levels. The main objective of this work was to investigate analytical methodologies that would allow the sensitive, selective determination of pollutants to be routinely possible. Polar, thermally labile sulfur-containing pesticides and pollutants were our focus analytes. This objective was achieved in two ways: 1) the development of supercritical fluid extraction procedures suitable for these compounds and 2) the interface of a sulfur-selective detector to chromatographic techniques appropriate for thermally labile compound analysis. Supercritical fluids, particularly CO₂, have recently been shown to be suitable replacements for traditionally used organic solvents in extraction. However, due to the polarity of the sulfonyl urea herbicides and thiocarbamate insecticides studied, pure CO₂ was found to be an ineffective extractant. Polar SF mixtures (2 and 5 % methanol-modified CO₂) were investigated as alternative supercritical extraction fluids. Of the modified fluids, only 2% methanol-modified fluid could be used due to post-SFE trapping problems encountered with the 5% modified fluid. The quantitative extraction of two of these herbicides from water at the 50 ppb level was achieved using the former SF. This SF was also used to extract three thiocarbamates from apples at the 2 ppm level. In order to achieve the second objective, a sulfur-selective gas chromatographic detector, the ozone-based sulfur chemiluminescence detector (SCD), was successfully interfaced to both packed column supercritical fluid chromatography (SFC) and microcolumn high performance liquid chromatography (micro-HPLC). The packed column SFC/SCD system was shown to be compatible with both pure CO₂ and methanolmodified CO₂ mobile phases with a detector sensitivity (2 pg S/sec.) comparable to that found with capillary SFC/SCD despite the presence of more CO₂, an effective chemiluminescence quenching agent. The equimolar response of this detector to sulfur was shown to be only somewhat affected by the coelution of other organic species and improper analyte combustion conditions. For micro-column HPLC/SCD, the detector was found to be compatible with methanol/water mobile phases. Mobile phase composition, mobile phase flow rate, air flow rate, and hydrogen flow rate were found to affect the detector's sensitivity. The detector's linear dynamic range, response factor, and detection limits were determined to vary as a function of mobile phase composition. Optimum sensitivity (600 fg S/sec.) was achieved with a mobile phase of 40% methano1l60% water mobile phase compositions investigated. The analysis of polyaromatic sulfur-containing hydrocarbons (PASH's), total sulfur in diesel fuel, and sulfonyl urea herbicides was realized with the SFC/SCD system while thiocarbamate pesticides from an apple matrix were examined with the HPLC/SCD system.
Ph. D.

Los estilos APA, Harvard, Vancouver, ISO, etc.

33

Eastling, Paul Michael. "Polychlorinated biphenyls in Cedar Rapids soil". Thesis, University of Iowa, 2010. https://ir.uiowa.edu/etd/492.

Texto completo

Resumen

Extreme flooding of rivers may contribute to increased loading of persistent organic pollutants (POPs) to the Great Lakes, the Mississippi river, and other large lakes and surface waters downstream of industrial and urban areas. This study examines the fate of POPs that were mobilized during heavy flooding of the Cedar River and the small urban city of Cedar Rapids, Iowa during the summer of 2008. This study focuses polychlorinated biphenyls (PCBs). We hypothesize that these PCBs were mobilized by the flood water and that residues remained in the soils and sediments of the residential areas of the city. To test our hypothesis, soil samples were collected from ~200 of residential locations in the downtown Cedar Rapids area and analyzed for the three compound groups. Samples were extracted using an accelerated solvent extraction (ASE 300), and analyzed using GC/ECD, GC/MSD and GC/MS/MS.

Los estilos APA, Harvard, Vancouver, ISO, etc.

34

Schuster, Jasmin. "Temporal and spatial trends of persistent organic pollutants in air and soil : implications for their sources and environmental cycling". Thesis, Lancaster University, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618816.

Texto completo

Resumen

Persistent organic pollutants (POPs) are defined by their characteristic properties in the environment, such as adverse effects on humans and other organisms, a low degradation rate, a potential for bioaccumulation and long range-transport. These properties are the reason that POPs are monitored in remote regions, like the Polar Regions and open oceans, even though they were mostly used in populated areas (urban or rural). A group of POPs was banned under the Stockholm Convention on Persistent Organic Pollutants in 2001 by a number of countries and more chemicals have been added to the list subsequently. To assess the effect of international regulation more information about the long-term fate of these chemicals, the transport processes and the exchange between different environmental media is needed. The first part of this thesis describes long-term trends of POPs such as polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in the environmental compartment air. One study discusses the trends that were observed with passive air samplers in remote locations along a transect across the UK and Norway. The air• concentrations monitored from 1994 to 2008 at 11 sites showed a general decline. While the total air concentrations decreased with increasing latitude, the decline rates did not differ between sampling sites. A second study discusses the trends of PCBs in the UK atmosphere for urban and rural sites. As in the remote areas, a steady decline was observed following first order kinetics. The PCB concentrations at each sampling site were directly proportional to the population density of the area. It was therefore concluded that air concentrations of PCBs are currently still defined by the direct input from primary source emissions and the observed decline mirrors a decline in emission. In order to assess the fate of POPs in other environmental media soil cores were collected following the transect for the passive air data across the UK and Norway. The soil cores were collected at identical locations ten years earlier. A direct comparison of the data between the sampling years proved that the decline in soil is more variable than in air for most monitored POPs. While there were nearly no changes in soil concentrations of organochlorine pesticides, there was a slight decline for PCBs and a strong decline for PBDEs. Changes in the burden, of PCBs per unit soil organic matter between 1998 and 2008 indicate the approach of soil-air equilibrium for the monitored sites. However chiral data and atmospheric data from the regions indicate that the influence of re-volatilization contributed only a minor component of the air burden of PCBs in remote areas of northern Europe. Important tools in monitoring regional and temporal trends of POPs are passive air samplers, which can be deployed at low cost in remote areas. A new type of sampling medium. the sorbent-impregnated polyurethane foam (SIP) disk, was assessed for its applicability for long-term monitoring of PCBs, PBDEs and hexachlorobenzene. Long-term deployment is a necessity for areas with low concentrations. In order to estimate the most precise atmospheric concentrations from the chemicals sequestered on the sampling medium, it would be preferable if the sampler and atmosphere are not in equilibrium and the sampled air volume is therefore directly proportional to the deployment time. It was found that the SIP disk presents a valid alternative to other established passive air sampling media. The last part of the thesis discusses a group of emerging POPs, the perfluorinated compounds (PFCs). PFCs were monitored in a passive air sampling campaign in different Asian countries. Differences were observed in the PFC composition at different sampling sites. These were explained with different usage pattern and regulations in the different countries. Further research is required to gain deeper understanding the transfer mechanism between different environmental compartments for POPs. The application of a model is needed to assess the increasing influence of secondary sources, i.e. revolatilisation from soils on atmospheric concentrations. While long-term studies for emerging compounds already exist, it is necessary to establish similar monitoring campaigns for emerging chemicals.

Los estilos APA, Harvard, Vancouver, ISO, etc.

35

Shamsudheen, Semeena Valiyaveetil. "Long-range atmospheric transport and total environmental fate of persistent organic pollutants : a study using a general circulation model /". Hamburg : Max-Planck-Inst. für Meteorologie, 2005. http://mpimet.mpg.de/de/web/download.php?src=max_erdsystem&file=pdfupload&id=23&filename=BzE_15.pdf.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

36

Pal, Shinjini. "The association between persistent organic pollutants, type 2 diabetes, and insulin resistance in two First Nations communities in Northen Ontario". Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28313.

Texto completo

Resumen

Recent evidence suggests an association between persistent organic pollutants (POPs) and type 2 diabetes. In two First Nations communities of high wild food consumption, specific objectives were formulated to: (1) compare POP levels between diabetics and non-diabetics; (2) investigate the association between POPs and insulin resistance in non-diabetics; and (3) determine the effects of POPs on certain inflammatory markers. Results indicated significantly higher age-adjusted plasma concentrations of some POPs in diabetics as compared to non-diabetics. Body mass index was found to be the most significant predictor of insulin resistance. There was a positive association of Tumour Necrosis Factor (TNF)-alpha with oxychlordane and mono/di-ortho substituted polychlorinated biphenyls (PCBs). Positive associations were detected between adiponectin and mono/di-ortho substituted PCBs as well as some pesticides. Results indicate that diabetics have higher levels of some POPs than non-diabetics. In non-diabetics, POPs are unrelated to insulin resistance although some are positively associated with inflammatory markers.

Los estilos APA, Harvard, Vancouver, ISO, etc.

37

Lind, Ylva Sjoberg, Monica Lind, Samira Salihovic, Bavel Bert van y Lars Lind. "Circulating levels of persistent organic pollutants (POPs) are associated with left ventricular systolic and diastolic dysfunction in the elderly". Uppsala universitet, Arbets- och miljömedicin, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-201797.

Texto completo

Resumen

Background and objective: Major risk factors for congestive heart failure (CHF) are myocardial infarction, hypertension, diabetes, atrial fibrillation, smoking, left ventricular hypertrophy (LVH) and obesity. However, since these risk factors only explain part of the risk of CHF, we investigated whether persistent organic pollutants (POPs) might also play a role. Methods: In the Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study, left ventricular ejection fraction, (EF), E/A-ratio and isovolumic relaxation time (IVRT), were determined by echocardiography and serum samples of 21 POPs were analyzed in serum measured by high-resolution chromatography coupled to high-resolution mass spectrometry (HRGC/HRMS) in 998 subjects all aged 70 years. Results: In this cross-sectional analysis, high levels of several of the polychlorinated biphenyls (PCB congeners 99, 118, 105, 138, 153, and 180) and octachlorodibenzo-p-dioxin (OCDD) were significantly related to a decreased EF. Some POPs were also related to a decreased E/A-ratio (PCBs 206 and 209). All the results were adjusted for gender, hypertension, diabetes, smoking, LVH and BMI, and subjects with myocardial infarction or atrial fibrillation were excluded from the analysis. Conclusions: Circulating levels of POPs were related to impairments in both left ventricular systolic and diastolic function independently of major congestive heart failure risk factors, suggesting a possible role of POPs in heart failure.

Los estilos APA, Harvard, Vancouver, ISO, etc.

38

Tolley, Cecilia A. "Persistent organic pollutants in white-tailed deer ( Odocoileus virginianus) near a magnesium smelter: Spatial distribution and human health risk assessment". Thesis, University of Ottawa (Canada), 2006. http://hdl.handle.net/10393/27187.

Texto completo

Resumen

A magnesium refining facility in Quebec was a known point source of persistent organic pollutants namely polychlorinated biphenyls, dioxins and furans, and hexachlorobenzene. Contaminants concentrations were measured in the fat tissue of local white-tailed deer with the assistance of the local community and hunters. Concentrations in the deer from 1999, one year before the smelter opened, were compared with deer from 2002. Results showed a significant increase in PCBs from 1999 to 2002, and total PCB concentrations showed significant decreases with distance from the smelter. Many of the mid-range PCB homologues that bioconcentrate sharply in deer showed similar relationships. Sigmacoplanar PCBs and Cytochrome P450 1A expression in liver also showed a significant inverse relationship with distance in 2002. Results of a human health risk assessment indicated that the number of deer meal portions required to exceed safe consumption levels for PCDD/Fs and coplanar PCBs increased with the distance from the smelter.

Los estilos APA, Harvard, Vancouver, ISO, etc.

39

Xu, Weiguang. "Risk assessment of dietary exposure to PCDD/PCDFs, DL-PCBs and NDL-PCBs of Hong Kong residents". HKBU Institutional Repository, 2012. https://repository.hkbu.edu.hk/etd_ra/1407.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

40

Cui, Danni. "Fundamental Mechanistic Studies on the Ultrasonic Treatment of Problematic Water Pollutants and Toxins". FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3913.

Texto completo

Resumen

Problematic organic pollutants in industrial and drinking water sources are a leading cause of water scarcity. Among the advanced oxidation processes, sonolytic degradation has received considerable attention because it combines oxidation processes initiated by reactive oxidant species and a pyrolysis processes associated with the high temperatures produced during cavitation. The degradation of the semi-volatile compound, MCHM, was rapid and followed pseudo-first order kinetics. The Freundlich kinetic model for heterogeneous systems was successfully applied to describe the non-uniform distribution of MCHM at the gas-liquid interface during ultrasonic treatment. Two primary products were confirmed by GC-MS. Computational studies were also applied to assist in a better understanding of the conformational effects and the pyrolytic pathways. The first-generation antihistamine, diphenhydramine (DPH), was also readily degraded by ultrasound. The heterogeneous process was best fit to a Langmuir-Hinshelwood kinetic model, which indicated a uniform partitioning at the gas-liquid interface. The degradation of DPH was achieved primarily via the addition reaction with hydroxyl radicals to the aromatic rings. Computational studies supported the observed products and the proposed reaction pathways for the pyrolytic and oxidation degradation pathways. Ultrasound was shown to be a rapid and effective method to remediate cetirizine (CET), a second-generation antihistamine. Addition of different hydroxyl radical scavengers into the solution prior to treatment as the competition studies indicated that CET reacted with hydroxyl radicals at the gas-liquid interface and the bulk solution. When the solution was saturated by O2, CET degraded the most rapidly. Degradation products were confirmed by LC-MS analyses. Treatment of the emerging problematic perfluorinated alkyl substance, “GenX” with steady state gamma-radiation under various conditions did not lead to significant degradation. However, “GenX” does react with eaq- at near diffusion-controlled rate, k = 5×1010 M-1·s-1. Titanium dioxide photocatalysis did not lead to appreciable degradation of “GenX” under a variety of conditions even in the presence of oxalic acid or ethanol as the valence band hole quencher. Sonolysis was a promising method and led to the effective mineralization of “GenX” under argon saturated conditions. A detailed computational study of the pyrolytic degradation pathways was carried out using density function in Gaussian 09.

Los estilos APA, Harvard, Vancouver, ISO, etc.

41

Zhang, Mengliang. "Determination of Environmental Pollutants by Gas Chromatography/Mass Spectrometry with Chemometrics". Ohio University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1418386921.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

42

Royle, Anna. "Characterisation and remediation of a canal sediment contaminated with heavy metals and organic pollutants". Thesis, Liverpool John Moores University, 2005. http://researchonline.ljmu.ac.uk/5790/.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

43

King, Sarah M. "Enhancement in Degradation of Environmental Pollutants: Fenton Degradation of 2,4,6-Trinitrotoluene and Photodegradation of Deepwater Horizon Crude Oil". ScholarWorks@UNO, 2012. http://scholarworks.uno.edu/td/1451.

Texto completo

Resumen

Pollution poses serious threats to both the environmental and the organisms that depend on their environment for survival. Due to the toxicity of most contaminants, there is a dire need for remediation of polluted sites. Remediation studies were conducted on two high priority pollutants: 2,4,6-trinitrotoluene (TNT) and crude oil. TNT was the most common explosive used in the 20th century. Continuous contamination has resulted in an urgent need for remediation. Fenton reagent provides an advanced oxidation process that is capable of remediating recalcitrant explosives, such as TNT. One drawback of Fenton chemistry is that the reaction requires acidic pH to prevent precipitation of iron. Our studies have investigated Fenton degradation of TNT at near neutral pH with several modifiers present: β-cyclodextrin, carboxymethyl-β-cyclodextrin, alcohols, and polyethylene glycol (PEG, MW 200, 400, or 600 g/mol). Fenton degradation was also carried out on other nitroaromatics to better understand the reaction mechanism with PEG 400. Further mechanistic studies investigated the production of nitrate and ammonium with and without PEG 400. The Deepwater Horizon oil spill devastated the Gulf of Mexico and the surrounding wetlands. There are several mechanisms for degradation of oil released into aquatic environments. Bioremediation is one of the most important remediation methods; however degradation becomes stagnant in low nutrient waters. Furthermore, larger molecular weight alkanes and polycyclic aromatic hydrocarbons (PAHs) are not readily available for biodegradation. Transformation of these molecules often requires initial photodegradation. We have investigated the photochemical transformation of oil films with and without photocatalysts present. To better understand the photochemical transformations that occur to the Deepwater Horizon oil, we have conducted additional studies with dispersants present.

Los estilos APA, Harvard, Vancouver, ISO, etc.

44

Procaccini, Carlo 1965. "The chemistry of chlorine in combustion systems and the gas-phase formation of chlorinated and oxygenated pollutants". Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9365.

Texto completo

Resumen

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999.
Includes bibliographical references.
A major concern during the combustion of chlorinated fuels is the formation of chlorinated organic pollutants, which are potentially dangerous to human health and to the environment. Observed combustion byproducts include suspected carcinogenic and toxic compounds, such as chlorobenzenes, chlorophenols, and polychlorinated dioxins, furans and biphenyls. AH of these pollutants are regulated by US-EPA emission standards. This research studies the conditions which favor the gas-phase formation of these chlorinated byproducts. Under fuel-lean conditions, oxygen and chlorine compete for the available hydrogen to form H2O and HCl respectively. Laboratory reactor experiments show that, at short residence times (<100ms), relatively large amounts of chlorine atoms and Ch can be present under oxygenrich conditions. A detailed kinetic model of the post-flame chemistry of chlorocarbon combustion is validated in the course of this study, and applied to the prediction of the levels of Cl atoms at the different stages of practical furnaces and incinerators. It is found that atomic chlorine can be present in the combustor gas at levels in the range of0.5 to 2.5%, at temperatures as low as 400-500°C. In the absence of other reactants, these radicals undergo recombination and form equivalent amounts of Ch in the final quenched products. Changes in the concentrations of chlorine products are shown to occur in response to the addition of trace organic species to the flue gas of chlorocarbon combustion. When small amounts of a combustible species (ethylene, methane or carbon monoxide) are injected into the hightemperature (T> 1100°C), oxygen-rich products of methyl chloride combustion, OH and 0 radicals, generated in the oxidation of the injected fuel, transform significant amounts of HCl to Cl radicals. If the chlorine-containing combustion gas is first cooled to an intermediate temperature (T<800° C), the effect of the hydrocarbon injection is to consume Cl radicals in reactions of H abstraction and to reduce the final concentration of Ch in the quenched products. Chlorine radicals and Ch can react with organic compounds and form stable chlorinated byproducts. Cl· can readily abstract H atoms from stable hydrocarbons, forming carbon-based radicals. At high temperatures, these radicals are promptly consumed in oxidation reactions, and low temperatures are needed for the formation of stable chlorinated species. However, the notion that kinetic constraints severely affect homogeneous pathways at the low temperatures has led several authors to doubt that significant contributions to the formation of chlorinated and oxy-chlorinated pollutants could come from gas-phase reactions. Homogeneous reactions involving free radicals are not slowed by decreasing temperature. The present research shows that chlorine atoms may survive temperature reductions and, if they mix with organic species at temperatures in the range of 500 to 900°C. they promptly react forming large amounts of chlorinated and oxygenated adducts. The gas-phase reactions of benzene with the chlorine species present in combustion products are shown to form chlorinated benzenes and phenols, with a yield of chlorinated products up to 12% of the total benzene consumed. It is shown that the presence of atomic chlorine is required to initiate these reactions and, therefore, conditions which increase the levels of Cl radicals in the combustion gas enhance the formation of chlorinated pollutants. Not only are chlorinated benzenes and phenols hazardous products per se, but they are also known precursors for the formation of poly-chlorinated dibenzodioxins, dibenzofurans and biphenyls, via low-temperature (300-500° ) catalytic pathways. Therefore, gas-phase reactions can explain the formation of a large fraction of the organic pollutants released from practical systems.
by Carlo Procaccini.
Ph.D.

Los estilos APA, Harvard, Vancouver, ISO, etc.

45

Chan, Kit Yan. "Dietary exposure, human body loadings, and health risk assessment of persistent organic pollutants at two major electronic waste recycling sites in China". HKBU Institutional Repository, 2008. http://repository.hkbu.edu.hk/etd_ra/943.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

46

Brault, Emily K. "Evaluating Persistent Organic Pollutants (POPs) and Mercury in the West Antarctic Peninsula (WAP) Food Web, with a Focus on Antarctic Fur Seals (Arctocephalus gazella)". W&M ScholarWorks, 2012. https://scholarworks.wm.edu/etd/1539617927.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

47

Rönn, Monika. "Environmental Contaminants and Obesity". Doctoral thesis, Uppsala universitet, Arbets- och miljömedicin, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-209807.

Texto completo

Resumen

Obesity is a worldwide problem affecting both children and adults. Genetic, physiological, environmental, psychological, social and economic factors interact in varying degrees, influencing body weight and fat distribution and the progress of obesity. Moreover, some anthropogenic chemicals have proven to be endocrine disrupting chemicals (EDCs) with the potential to interfere with different actions of hormones in the body. EDCs may thereby disrupt homeostasis, modifying developmental, behavioral and immune functions in humans and animals, and also promoting adiposity. Because hormones generally act at low concentrations, small changes in the endocrine system may lead to extensive effects. Based on data from experimental and epidemiological studies this thesis elucidates the relationship between a large number of environmental contaminants and obesity. The experimental studies demonstrated that fructose supplementation in the drinking water resulted in unfavorable metabolic alterations such as a higher liver somatic index (LSI), an increase in plasma triglycerides and increased plasma levels of apo A-I. Fructose in combination with exposure to bisphenol A (BPA) increased liver fat content and plasma levels of apo A-I in juvenile female Fischer 344 rats. The experimental studies also showed that the retro-peritoneal fat, which in rats is a distinct fat depot easy to distinguish and dissect, correlated well with the measurements of total fat mass analyzed with MRI, and could therefore be used as a substitute for total fat mass in rats. The epidemiological studies showed that circulating levels of persistent organic pollutants (POPs) were related to fat mass measured by DXA. OCDD, HCB, TNC, DDE and the less chlorinated PCBs were positively related to fat mass, while the more highly chlorinated PCBs showed a negative association. Further, circulating levels of BPA were positively associated with levels of the hormones adiponectin and leptin, but negatively related with ghrelin, hormones which are involved in the regulation of hunger and satiety. However, serum BPA levels were not related to measures of fat mass in the elderly individuals in the PIVUS cohort. This thesis concludes that environmental contaminants such as BPA and POPs most likely are contributors, along with genetic, social and behavioral factors, to the development of obesity.

Los estilos APA, Harvard, Vancouver, ISO, etc.

48

Giri, Atanu. "Development of Photocatalysts Supported on Graphitic Carbon Nitride for the Degradation of Organic Water Pollutants". VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5692.

Texto completo

Resumen

Graphitic carbon nitride (g-C3N4) heterojunction composites with the semiconducting metal oxides, CeO2, ZnO and TiO2 are prepared in situ by co-calcination of the precursor materials or by a solvothermal method. The structural, morphological and the optical properties of the prepared materials are studied using various microscopy and spectroscopy techniques. The synthesized composite materials, CeO2/g-C3N4, ZnO/g-C3N4 and TiO2/g-C3N4 are more efficient in the photocatalytic degradation of the water pollutants indigo carmine (IC) and atrazine than the pure metal oxide, g-C3N4, or their physical mixtures. The CeO2/g-C3N4 and ZnO/g-C3N4 composites also exhibit improved degradation efficiencies of atrazine as compared to the individual metal oxide or g-C3N4 materials. The improved photocatalytic activity of the composites are attributed to the effective electron-hole charge separation within composite heterojunction, resulting from the well matched energy levels of the metal oxide and g-C3N4. This strategy could be helpful for the synthesis of other metal oxide and g-C3N4 composites for photocatalytic applications.

Los estilos APA, Harvard, Vancouver, ISO, etc.

49

Hansson, Henrik. "Reduction of Pollutants in Stormwaterand Processwater from the WoodIndustry by Electrocoagulation". Thesis, University of Kalmar, School of Pure and Applied Natural Sciences, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:hik:diva-2530.

Texto completo

Resumen

Although wood floor production does not use water in the production process, water consumptionis related to cleaning and washing of floor and machineries in different steps of the process line,which generate a number of small flows that are highly polluted.Besides this, the industry has a need to store large amounts of wood outside to be able to havecontinuity in the production. This takes up a lot of space outdoors and once it rains the water thathas been in contact with wood, oil and metals forms stormwater, which transports pollutants.Stormwater has for a long time not been seen as a problem and has often been discharged intorecipient water bodies without any treatment. During cold seasons, this also involves snowmelt thatcan transport high concentrations of different pollutants.This report describes the composition of process- and stormwater from a wood floor industry inNybro, Sweden regarding parameters such as COD, phenol, tannin and lignin. The concentrationsof phenols in the stormwater were found in a range considered toxic to marine life.Regarding the process water, high values was found for COD (Chemical Oxygen Demand) and forother substances and elements potentially toxic (e.g. formaldehyde, wood resins, detergents andmetals). If these waters are directly released to a sewage treatment plant without any pre-treatmentprocess it can disturb the plant treatment efficiency; if released to a recipient water body, it cancause oxygen deficiency and consequently, death to marine life.The possibility of reducing the levels of pollutants through the use of electrocoagulation has beenexamined in this study. This has been done both for process water and stormwater from the woodfloor industry. A 250 ml batch unit for electrocoagulation EC was setup with iron (Fe) andaluminium (Al) electrodes for treating process water and stormwater. The results show that the ECprocess can reduce COD concentration from stormwater at least 70%. On the other hand, lessefficiency of EC for treating process water was observed.A method for simulating a snowmelt period in lab scale was also developed. Snow collected from awood floor industry was melted according to real temperature and the quality of these samples hasthen been compared to on-site samples of stormwater

Development of an integrated approach for industrial wastewater and stormwater management in the wood-industry sector

Los estilos APA, Harvard, Vancouver, ISO, etc.

50

Peterman, Paul Herbert. "Evaluation of Human Toenail as a Non-invasive Biomonitoring Matrix for Assessing Human Exposure to Environmental Organic Pollutants by Optimized Sample Prep and GC/HRMS Analysis". Thesis, University of Missouri - Columbia, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=13877161.

Texto completo

Resumen

Human biomonitoring is an analytical challenge to find environmental organic chemicals of varying polarity, persistency, and potential toxicity in a suitable, ideally non-invasive matrix at ppb levels that are significantly above method blanks. Compared with more traditional matrices of adipose tissue, serum, and urine, toenail clippings samples are non-invasive, compact, can be shipped without refrigeration, stored indefinitely at room temperature, and processed without concerns for biohazards. With both hydrophilic and hydrophobic layers, toenails contain 1-2% lipid, which is several times higher than serum. Toenails grow slowly and are trimmed every 2-3 months, which offers the potential to integrate both chronic and pulsed episodic exposures. Using toenail samples (65 to 340 mg) donated from four individuals and an indoor house cat, the hypothesis that toenails are a suitable biomonitoring matrix was tested by analyzing for persistent pesticides, over 50 PCB congeners, moderately persistent PBDEs, and transient compounds of triclosan and bisphenol A by using GC/High Resolution MS (GC/HRMS) analysis and for unsuspected compounds using GC/full scan MS. Although not fully digested and dissolved, toenails averaged 1.22% lipid (sd 0.20%, n=10). Lipid was separated and determined using a new small single-use 2-g S-X3 gel permeation chromatography flash column with high purity nitrogen. Multiple toenail samples from one individual were collected for over a year for replicate analysis, p,p’- DDE averaged 0.82 ng/g-nail, sd 0.28, n=5 and 65.2 ng/g-lipid, sd 15.3, n=5 on lipid-adjusted basis. Trans-nonachlor averaged 3.08 ng/g-nail, sd 1.03, n=5; mean 254 ng/g-lipid, sd 97, n=5. PBDE 28 averaged 0.29 ng/g-nail, sd 0.10, n=5; mean 24.8 ng/g-lipid, sd 13.3, n=5. PBDE 85 averaged 0.25 ng/g-nail, sd 0.06, n=5; mean 20.8 ng/g-lipid, sd 6.2, n=5. PBDE 153 averaged 1.82 ng/g-nail, sd 0.51, n=6; mean 150 ng/g-lipid, sd 49.3, n=6. Most effectively biomonitored in toenails were normally transient triclosan (mean 58.3 ng/g-nail, sd 6.6, n=2), chlordanes, DDT, PBDEs, and PCBs including congeners with 2,5- or 2,3,6-chlorine substitution (PCBs 52, 49, 44, 70, 95, 101, 87, and 110), which are suspect neurotoxins, but are rarely found in extant serum biomonitoring data. Toenail soap wash samples indicated little (< 4%) or no exogenous contamination, except for the musks galaxolide and tonalide in most samples, which ranged up to 30%, likely from topical application. The one cat toenail sample had elevated concentrations of PBDEs and especially chlordanes. Unsuspected tentatively identified compounds included a UV Filter compound, octocrylene, a hydroxyl-methyl benzothiazole, and several compounds used in flavors or fragrances.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Tesis sobre el tema "Environmental chemistry. Persistent pollutants"

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros