Dissertations / Theses: 'Metal contamination'

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Poniger, S., H. Tochon-Danguy, H. Sachinidis, K. Alt, C. Hagemeyer, and A. Scott. "Reducing metal contamination in Cu-64 production." Helmholtz-Zentrum Dresden - Rossendorf, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-166071.

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Introduction In the past several years there has been a growing interest in the development of radiopharmaceuticals labeled with metallic radionuclides (Anderson et al. 1999). Of particular interest is the positron emitter Cu-64 (t½ = 12.7 h) for molecular imaging of small molecules as well as peptides and antibodies (Smith 2004). This has led us to the recent implementation of a solid target production facility using commercially available target irradiation station and chemistry modules. Routine production of Cu-64 was achieved with an average production yield of 0.32 mCi/μAh, however purification of Cu-64 has proven to be problematic; with several metallic contaminants compromising subsequent radiolabeling. We report in this work, the step by step procedure which led us to the successful production of low metal contaminant 64Cu with high specific activity and high labeling efficiency. Material and Methods Detailed implementation of our solid target was reported earlier (Poniger et al. 2012). A Nirta Solid Target from IBA was coupled to our 18/9 cyclotron using a 2-meter external beam line. A pneumatic solid target transfer system (STTS) designed by TEMA was use to deliver the irradiated target disks to a dedicated hotcell. Modules from IBA (Pinctada metal) were used for electroplating 64Ni onto a Ag disk and for acid dissolution and purification of the irradiated target. Typical irradiation parameters were 14.9 MeV at 35 μA for 5–6 hours with 64Ni plating’s ranging from 10–60 μm thickness at 6–12 mm. Radionuclidic purities were evaluated by gamma spectroscopy and traces of metallic impurities were determined by ICP-MS or ICP-AES. Labeling efficiency was evaluated by measuring the amount of 64Cu uptake per 20 μg of scFv-cage. Results and Conclusion Initial 64Cu purifications following the manufacturers recommended method resulted in high levels of Cu, Fe and Zn metal contaminants (see TABLE 1, ID 1). Note that little Ag contamination is observed nevertheless the 64Ni is plated directly on a Ag disk. After several productions, visual inspection of the module quickly revealed that the heater block used for heating the back of the Ag target disk was heavily corroded. Replacing the copper heater block with a PEEK heater block drastically reduced the levels of Cu and Fe contaminants. Unfortunately unusually high levels of Zn were still observed regardless of the stringent conditions and ultrapure reagents used during the processing (see TABLE 1, ID 5). In our quest for answers, ICP-MS analysis of the 64Ni plating solution as well as critical stock reagents such as Milli-Q water (18 MΩ cm−1) and 30% HCl TraceSelect Ultra (Sigma) was performed (see TABLE 1, ID 2,3,4). The results were surprising, with high level of Zn found not only in the 64Ni plating solution, but as well in the HCl TraceSelect Ultra. It was hypothesized that the Pinctada’s glass bottles (Kay, 2004) used to store the reagents, especially concentrated acidic solutions were the source of Zn contamination and all glass bottles were replaced by LDPE or PFA types. Our hypothesis was confirmed by subsequent ICP-MS analysis of fresh samples of HCl TraceSelect Ultra and the 64Ni plating solution prepared/stored in plastic containers (see TABLE 1, ID 6,7). We also confirmed by ICP-MS analysis that no contamination occurred when performing a non-radioactive dissolution/purification sequence on the Pinctada module using a blank PTFE target disk in conjunction with the change to plastic reagent storage bottles (see TABLE 1, ID 8). Initially the purification protocol was modified as described by Ometakova et al., 2012 to help reduce the co-elution of Zn contaminants with the 64Cu from the AG1-X8 resin. This change resulted in a significant amount of 64Cu eluting from the resin during the resin washing steps, so that protocol was abandoned and the protocol as described by Thieme et al., 2012 was adopted. By modifying the AG1-X8 resin washing protocol to this new method and eluting the 64Cu from with 0.1M HCl rather than Milli-Q water (see TABLE 1, ID 9), we were able to further reduce metal contaminants, especially Zn. During the course of these experiments, the true specific activity of 64Cu increased from as low as 12 mCi/μmol of Cu (n = 2, TABLE 1, ID 1) to 649 mCi/μmol of Cu (n = 7, TABLE 1, ID 5) and finally to 4412 mCi/μmol of Cu (n = 3, TABLE 1, ID 9). In the same time, the effective specific activity increased from 0.03 ± 0.02 mCi per 20 μg of scFv-cage, to 3.7 ± 0.3 mCi per 20 g of scFv-cage with 64Cu. In conclusion, a significant reduction in Cu, Fe and Zn contaminants was achieved when processing 64Cu using the Pinctada module: i) after replacement of the Cu heater block; ii) after elimination of glass reagent storage containers from the Pinctada module and procedures during preparation of the 64Ni plating solution and iii) after implementation of a new purification protocol (Thieme et al. 2012). Introduction of a 6M HCl wash-up cycle of the module prior to the dissolution procedure was also effective. However in recent 64Cu productions slightly elevated Ag levels have been observed and are under investigation (see TABLE 1, ID 9).

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Durrant, Christopher. "Effects of metal contamination on fish populations." Thesis, King's College London (University of London), 2010. http://kclpure.kcl.ac.uk/portal/en/theses/effects-of-metal-contamination-on-fish-populations(cd690b4f-265d-48cd-805e-c561e411b370).html.

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Sabet, Mitra Deliri, and n/a. "Aquatic plants as indicators of heavy metal contamination." University of Canberra. Resource, Environmental & Heritage Sciences, 1997. http://erl.canberra.edu.au./public/adt-AUC20061107.161814.

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Concentrations of heavy metals (Cu, Cd, Cr, Zn, Mn, Fe and Pb) in the water columns, aquatic plants and sediments of fourteen lakes of varied levels of pollution were measured. Correlation analysis was carried out between heavy metal concentrations in aquatic plants and heavy metal concentrations in water and sediment. The aquatic plants which accumulated heavy metals in their tissues in proportion to that in water and sediments were identified. The aquatic plants studied were: 8/yxa auberti Rich, Cabomba caroliniana Gray, Ceratophyllum demersum L, Ceratopteris thalictroides (L.) Bron, Chara globularis, Eichhornia crassipes Solmn, Hydrilla verticillata Royle, Ipomoea aquatica Forsk, Limnophila aromatica (Lam.) Merr., Ludwigia adscendens (L) Hara, Nelumbo nucifera Gaertn, Nymphaea stallata Linn, Nymphoides indica (L.) Kuntze, Typha angustata Bony & Chaub and Utricularia aurea Lour. Metal uptake by aquatic plants varied between different species and within the same species depending on lake water contamination levels. The level of metal uptake to a great extent was a function of the environment water metal concentration. Results showed that Utricularia accumulated Mn, Zn, Cr, Cd and Pb in direct proportion to the overlying waters (r2 = 0.69, 0.63, 0.69, 0.65 and 0.39 respectively). Hydrilla accumulated Cu, Mn, Zn, Fe, Cr, Cd and Pb in direct proportion to the overlying waters (r2 = 0.65, 0.66, 0.44, 0.72, 0.38, 0.63, and 0.73 respectively). Blyxa leaves accumulated Zn, Fe, Cr, Cd and Pb in direct proportion to the overlying waters (r2 = 0.74, 0.74, 0.72, 0.60 and 0.82 respectively). Echhornia leaf accumulated only Cr in direct proportion to the overlying waters r2 = 0.81. Nymphaea leaf and Chara did not accumulate any metal in direct proportion to the overlying waters. Roots of Blyxa auberti, Ceratopteris thalictroides, and Eichhornia crassipes contained higher concentrations of heavy metals than their leaves. Roots of Blyxa accumulated Cr, Cd and Pb in direct proportion to the overlying waters (r2 = 0.91, 0.65 and 0.69 respectively). Echhornia root accumulated Cd in direct proportion to the overlying waters with r2 = 0.90. Nymphaea stem showed no significant correlations between the metal concentrations in the waters and in the plant. Utricularia accumulated Zn, Fe, Cr, Cd and Pb in direct proportion to the metals in the underlying sediment extracted by cold hydrochloric acid (r2 = 0.84, 0.51, 0.47, 0.68 and 0.80 respectively). Hydrilla accumulated Cu, Zn, Cr, Cd and Pb in direct proportion to the underlying sediment (r2 = 0.34, 0.37, 0.91, 0.49 and 0.96 respectively). Blyxa accumulated Zn, Fe, Cr, Cd and Pb in direct proportion to the underlying sediments (r2 = 0.99, 0.61, 0.82, 0.75 and 0.64 respectively) . Echhornia leaf showed significant correlation between the Cu (r2 = 0.83) and Cr (i2 = 0.88) concentration in underlying sediment and the plant. Nymphaea leaf showed a significant correlation between the Zn (r2 = 0.83) concentration in the plant and the underlying sediments. Roots of Blyxa showed significant correlation between concentrations of Cu, Cr and Pb in sediment extracted by hydrochloric acid and plant (r2 = 0.9, 0.7 and 0.9 respectively). Roots of Echhornia had no significant correlation with the sediment metal concentrations (hydrochloric acid extractable). Two techniques (cold hydrochloric acid extractable and nitric acid extractable) to extract metals from sediment were compared. Based on correlations of metal concentrations in plant tissue and metal extracted from the sediment, it was concluded that the cold hydrochloric acid extractable metal technique is more suitable for determining bioavailable sediment metal concentration in environmental studies. Laboratory studies investigations on the bioaccumulation of Zn and Cu in Hydrilla confirmed that Hydrilla is a good bioindicator of Cu as it accumulated 20360 ug/g dry weight of Cu in 72 hours. Hydrilla showed higher bioaccumulation factor with low concentration of Cu in the solution, in the laboratory studies. Hydrilla was determined to be the best indicator species as it reflected the heavy metal concentration in the environment which was supported by the laboratory studies.

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Watts, Sarah Jane. "Recovery of the Mersey Estuary from metal contamination." Thesis, University of Plymouth, 2004. http://hdl.handle.net/10026.1/2133.

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The Mersey Estuary has received significant quantities of industrial wastes and sewage over several decades. Although contarninant loads are reducing and the estuary is showing signs of recovery, the sediment reservoir remains a repository of historical contamination and still contains high concentrations of trace metals and organic compounds. A combination of hydrodynamic, sedimentary and geochernical processes are responsible for maintaining trace metal concentrations at present-day levels. The distributions of trace metals in bed sediments reflect changes in granulometry, differences in POC content and the magnitude of past inputs rather than the locations of point sources in the estuary. The association of contaminant metals with SPM varies not only with axial changes in salinity and particle concentration but also in response to the relative magnitudes of freshwater and tidal inflows and cyclic variations in water and particulate chemistry that occur on intratidal, intertidal and seasonal timescales. The most influential of these arise from axial changes in dissolved oxygen and the delivery. of organic carbon from both external and internal sources which modify the relative degree of sorptive control exerted by Fe, Mn and organic C at different locations in the estuary and at different times. These factors, combined with the efficient trapping of sediments and possible salting out of neutral metalorganic complexes, assist in the retention and internal recycling of particles and associated metals betweent he bed and water column. Geochernicalr eactivity is suppressedin Mersey SPM and metal decontamination is not predicted to occur through the loss of particulate metals to the surrounding coastal zone. Rather, it is envisaged that sediment resuspension and the desorption of metals into fresh and low salinity waters, supplemented by the release of metals from tidally stirred diagenetically modified sediments, are more likely to be important long term cleansing mechanisms, with the latter occurring particularly during the summer months when bacterial numbers and the degradation of accumulated organic detritus becomes more pronounced. Futured eclinesi n metalsf rom bed sedimentsh aveb eene stimatedu sing two methodsa nd two independendt ata sets. Resultingv aluesa re not only metal-dependenbtu t also vary with sedimentlo cation.L osseso f Cd, Co, Cu, Hg, Ni andZ n arep redictedt o takeu p to 40 years,w hilst removal of substantiallye levatedc oncentrations of Pb in sedimentsin the upper estuary could span hundreds of years.

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Brodd, Patrick. "Long term heavy metal contamination from leakage water sediments." Thesis, Uppsala University, Department of Earth Sciences, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-88909.

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Hall, C. J. "Trace metal contamination of lakes and ponds in London." Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1409852/.

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Few studies of metal pollution in lakes have been carried out in urban environments. This research aimed to determine both temporal and spatial changes in metal concentration in sediments of lakes in London, and identify the current extent of contamination in lake ecosystems as a whole. The novel use of sediment archives to reconstruct potential toxicity was also explored. Sediment cores were taken from seven lakes across London and analysed for Ni, Cu, Zn, As, Pb and Hg concentrations. The cores were dated using a combination of radiometric and SCP dating, and lake age. Temporal trends were found to vary within and between sites, due to metal behaviour, catchment disturbance and the proximity to and type of metal source. PCA showed that there was some evidence for a regional pattern of contamination. Across all sites metal concentrations were very high, exceeding guideline values both in the past and at present. At various times the concentration of Pb had reached levels that were over 2000% higher than the guideline value. Increasing levels of enrichment and flux towards the surface of the cores also showed that contamination was not declining. Metal concentrations were also determined in deposition, water, and biota at one of the lakes. The concentration of Pb was found to exceed guideline values in both water and fish. The extent of Pb contamination in London lakes is therefore a major cause for concern. The potential toxicity of the combination of metals analysed in the sediment cores was reconstructed, through the calculation of mean toxicity quotients. Every core exceeded the potential toxicity threshold at all depths. Comparison to laboratory toxicity test data carried out on sediments from the OPAL lakes showed that the sediments were likely to be toxic, which would have implications for lake ecosystems should they be disturbed.

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Buchholz, Florian. "Metal surface contamination in c-Si solar cell processing." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2016. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-203660.

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Fe und Cu wurden als Schlüsselspezies für die Betrachtung von Oberflächenkontamination in der Prozessierung von c-Si-Solarzellen identifiziert. Studien mit gezielt aufgebrachten Metallkonzentrationen vor verschiedenen Passivierungs- und Diffusionsprozessschritten ergaben relativ hohe kritische Werte für Cu, außer bei thermischer Oxidation. Niedrige Werte wurden für beide Elemente vor Hochtemperaturschritten im n-Typ-Hocheffizienzprozess beobachtet, wobei sich die B-Diffusion als etwas weniger empfindlich darstellte. Temporäre Gettereffekte für Fe (in p-Typ-Si) und Cu (in n-Typ-Si) wurden beobachtet. Es zeigte sich, dass As-Cut-Wafer, unabhängig von der Sägeart (SiC-slurry oder Diamantdraht) sehr hohe Metallverunreinigungen (im Bereich 1*1011 – 5*1014 cm-2) in den Prozess einbringen. Das alkalische Ätzen verringert diese Menge kaum, was hohe Anforderungen an die anschließende Reinigung ergibt. Die Optimierung von HF/O3-Reinigungslösung für diese Flächen ergab beste Reinigungsergebnisse bei niedrigen HF-Konzentrationen, abhängig vom alkalischen Ätzschritt und anschließendem HCl/HF-Dip.

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Gilbert, Lucy Jane. "Heavy metal contamination in the Black River, Cape Town." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/19961.

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Urban river sediments are often contaminated as a result of development and anthropocentric activity, and the Black River in Cape Town is a prime example of a river system suffering from unsustainable development. Methods of deter mining total and background concentrations of selected heavy metals were researched and utilized in the effort to quantify heavy metal concentrations derived from anthropogenic sources in the Black River . The findings were intended for use in the aim of producing sediment quality guidelines (SQG) for South Africa as described in the Water Research Commission Phase I Report; Developing Sediment Quality Guide lines (Gordon and Muller, 2010). The ability of the invasive Eichhornia crassipes (water hyacinth) to uptake and store heavy metals was also briefly investigated to identify its potential as a phyto - remediator in the Black River. Toxicity of the sediment was quantified using the consensus - based mechanistic approach (Gordon & Muller, 2010) whereby assuming that total concentration of a heavy metal is the critical factor in its hazardousness. Sediment samples were divided into grain size and measured by X - Ray Fluorescence and concentrations of the focus elements antimony, arsenic, cadmium, chromium, copper, nickel, lead, and zinc in the mud fraction were compared with Consensus Based Sediment Quality Guidelines (McDonald et al., 2002). Based on guide line exceedances, the most toxic sample was collected from anoxic sediment conditions at the point where the N2 Highway crosses the Black River. The succeeding high toxic ity risk locations were all within areas slightly downstream of a river convergence or within 50 m of one, specifically the Vygekraal, Jakkelsvlei, Esliekraal and Kromboom rivers. Exceedances were most common for chromium, copper, lead, nickel and zinc. The least toxic sample was collected 160 m downstream of the Athlone wastewater treatment works, with the one sample collected between these two points also holding relatively low toxicity risk. Concentrations of the selected analytes were also compared to results from a previous study conducted in 2002 on the Black River sediment (Haniff). The comparison suggested contamination has generally worsened in the past 13 years however due to potentially large analytical error from the differences in sample analyses in 2002 and in this investigation; the reliability of the comparative study is limited to general observation. The data implies that the Athlone wastewater treatment works was contributing to heavy metal concentrations in the sediment in 2002, but now in 2015 appears to improve sediment quality. The Water Research Commission Phase I report identifies four ways to assess sediment quality to produce SQG; one of which is to establish normal background concentrations. In this investigation, background concentrations of heavy metals from natural sediment input to the Black River was estimated using two methods, the first was by combining globally recognized average shale values (Turekian and Wedepohl, 1961; USGS, 2000) with results obtained from studies undertaken on virgin soils of the Black River catchment area (Soderberg, 2003; Herselman, 2007) to form what is referred to as Estimated Background Values (EBV). The second method was to measure element concentrations of weakly - acid rinsed and milled coarse grain fraction of the Black River sediments. This was to see whether concentrations of the coarse fraction reflect those of the EBV, and to establish whether this would be a feasible method of estimating background concentrations which takes into account the multiple inputs of natual sediment across the river catchment. It was concluded from the application of the t - test that the coarse grain fraction held similar concentrations to 19 major and trace elements of the EBV with 95% certainty, and were comparable for all the focus elements accept antimony and arsenic. The mud fraction heavy metal concentrations were then applied to three statistical indicators; the Pollution Load Index (PLI), the Geo - accumulation Index (I - Geo) and the Enrichment Factor (EF) in the objective to quantify anthropogenic input using both the EBV and coarse grain fraction results as reference values. All statistical indicators suggest the river is most enriched with cadmium, copper, lead and zinc, which most likely derive from roadside deposit/stormwater drainage and industries. The application of EBV to the statistical indicators revealed relatively little pollution enrichment, whereas the coarse grain results suggested much higher leve ls of pollution enrichment in the Black River. This disparity verifies the importance in selecting/obtaining suitable data sets as screening values for investigating heavy metal enrichment (Gałuszka & Migaszewski, 2012). It was concluded that the coarse grain fraction element concentrations would not be feasible for use as EBV in the case of the Black River. This is due to the large assumptions made whilst using this method, namely that the coarse grain fraction is assumed to derive from the same source as the mud fraction. Due to the known disturbances to natural sedimentation in the Black River, it is doubtful that the fractions come from the same source. Also given the relatively low heavy metal concentration in the coarse grain fraction, it is likely that the majority of the sand in the sediment of the Black River derives from the coastline. Heavy metal concentrations in the water hyacinth and sediments were applied to the Bio - accumulation Factor to identify the potential of the species as a phyto - remediating agent in the Black River. All four water hyacinth samples contained high concentrations of cadmium, and high concentrations of arsenic, nickel and antimony in three samples. Mercury was present (albeit at low concentrations) in three out of the four plant samples, yet was not detected in any of the 32 sediment samples, supporting the conclusions of Buta et al (2011) that the plant has a very strong affiliation to mercury, and that the element has a high affinity to bind with dissolved organic carbon and suspended sediment. The Bio - accumulation Factor revealed the phyto - remediation potential of the water hyacinth is high for antimony, arsenic, cadmium, mercury, lead and nickel. Water hyacinth could therefore be utilized more effectively (with the use of controlled growth) to remediate sediments indirectly by removing heavy metals from the water and preventing them settling into the sediment. Short - term fluctuations in heavy metal presence and kinetic components cannot be conservatively evaluated due to sediment disturbances, complexities within river system inputs and the ever changing environmental conditions. The findings are based on equilibrium status and the conditions at the time of sampling, and are limited to confinements of the reliability of data generated from sample collection, preparation methods and sample analysis. The distribution of metals in sediments of the Black River if not controlled by dredging is generally controlled by the association of heavy metals with very fine grained, organic - rich sediment. In addition, locations of high element enrichment reflect other river inputs which drain from various areas of the Cape Flats, with the most significant being the Esliekraal convergence. Conclusions from the investigation suggest the method of establishing background concentration from the coarse grain fraction could be applicable only to urban rivers which have seen few sedimentation disturbances and are relatively isolated from externa l sources away the local catchment. This method could reduce sampling costs and be used along with the application of other means available mentioned in the Water Research Commission Phase I report to create South African sediment quality guidelines.

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Zhang, Liming 1966. "Contamination and galvanic corrosion in metal chemical-mechanical planarization." Diss., The University of Arizona, 1998. http://hdl.handle.net/10150/282840.

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Chemical mechanical planarization (CMP) of metals is a critical process in the manufacturing of ultra-large scale integrated (ULSI) circuit devices. The overall success of a CMP process requires minimal particulate and metallic contamination of the structures subjected to CMP. The objective of this study was to investigate alumina particle contamination during tungsten CMP, copper contamination in copper CMP, and galvanic corrosion between metal films and adhesion layers during the final stages of tungsten and copper CMP. Particular attention was paid to the use of short chain organic carboxylic acids in reducing the contamination. Both electrokinetic and uptake measurements showed that citric acid and malonic acid interact with alumina particles by electrostatic as well as specific adsorption forces. Systematic immersion contamination and polishing experiments were carried out to demonstrate the effectiveness of the acids in controlling alumina particulate contamination on wafer surfaces. The difference in the surface cleanliness was interpreted using the electrokinetic data and the calculated interaction energy between alumina particles and the wafer surface. Electrochemical tests showed no severe attack on tungsten films by the acids. Copper ions were found to adsorb onto the silicon dioxide surface, leading to copper contamination levels of upto 10¹³ atoms/cm². The extent of copper contamination was found to depend on the solution pH and the presence of additives such as hydrogen peroxide. Both electrokinetic measurements and immersion contamination experiments showed that citric acid can reduce the copper contamination on the silicon dioxide surface. TiN is more noble than tungsten in the solutions containing oxidants used in tungsten CMP slurries. The most significant corrosion of tungsten was found in the presence of hydrogen peroxide. Copper was found to be more noble than tantalum in acidic solutions. However, in alkaline ammonium hydroxide solutions, the relative nobility of copper and tantalum can be reversed by adding hydrogen peroxide. The corrosion of tungsten and copper appears to be very minimally affected by coupling with TiN and tantalum, respectively.

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Valencia, Avellan Magaly Genoveva. "Heavy metal contamination of river water : sources, behaviour and remediation." Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/18772/.

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Pollution from metal mining has led to severe environmental damage. The assessment of metals is very complex as they interact with a broad spectrum of biotic and abiotic components depending on physicochemical conditions. Worldwide, discharges from ancient mines are considered one of the major causes of point and diffuse pollution. This thesis investigated the sources and mobility of metal pollution associated with historical mining in a carboniferous upland catchment, located in the Northern Pennines in the UK. From chemical analysis and geochemical modelling I identified metal sulphates and metal carbonates as the main mineral sources of metals. I also demonstrated that metal carbonates are controlling metal mobility, while seasonality is also producing changes in flow and pH conditions, affecting metal concentrations and behaviour. By using speciation modelling, ecotoxicological assessment tools and in situ macroinvertebrate survey I highlighted the dynamics of metals occurring in neutral mine drainage; and suggested the application of environmental quality standards based on bioavailability data within a realistic context relating response of aquatic organisms to river water chemistry and metals. I also evaluated the effects of episodic rainfall on aqueous metal mobility and toxicity to address some knowledge gaps. I found that rainfall conditions did not alter the circumneutral conditions of the catchment, although metal mobility and speciation were affected by the abundance of carbonate and bicarbonate minerals derived from bedrock weathering. I showed that metal toxicity occurred at circumneutral pH, and mainly attributable to zinc. Moreover, I assessed the effects of episodic rainfall in metal toxicity and calculations revealed that short-term fluctuations of metal concentrations are not reflected in the predicted acute toxicity risk to aquatic organisms, underlining the complexity of chemical speciation especially during episodic events. Likewise, I provided a baseline for future mitigation strategies for catchments under risk of metal pollution. Finally, I stressed the importance of the public perception and community involvement in a holistic management of catchments for protecting riverine ecosystems and improving their water quality. Overall, this thesis provides the evidence that a comprehensive metal assessment requires a great understanding of processes and reactions occurring from metal sources to potential endpoint environments (e.g. water, sediments, and biota). For regulatory purposes, technical knowledge needs to be sensibly transferred to the community for achieving an effective integrated catchment management. Findings from this thesis are suitable for the assessment of streams draining spoil waste areas with similar geochemical conditions and inform future management strategies.

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Schmid, John Robert 1952. "A model for estimating allowable transition metal contamination in DRAMs." Thesis, The University of Arizona, 1993. http://hdl.handle.net/10150/291463.

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Due to new memory-cell architectures, the leakage-current requirements for semiconductor memories will become less stringent with increased levels of integration. The implication of these requirements with regard to allowable metallic contamination levels is investigated with a one-dimensional model based on Shockley-Read-Hall generation-recombination. The model was developed to predict leakage-current in carrier-depleted regions as a function of basic process and metallic contaminant parameters. As device dimensions are reduced, transition metal homogeneous contamination in process chemicals can be an important source of generation-recombination centers that result in the dominant generation-current in the space-charge region. The model allows an estimation of an upper bound for transition metal contamination in advanced processes and is applied for DRAM leakage predictions. Using the model, it is demonstrated that the trend toward lower leakage-current density requirements reverses after the 64-Mbit generation DRAM as a result of memory-cell architecture trends which significantly reduce the space-charge volume.

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Lin, Zhi-Qing. "Trace metal contamination in forests of southern Quebec and pathway studies of airborne metal deposits." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40177.

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Trace metal contamination of the air-soil-tree system was examined in southern Quebec, where acid deposition and tree dieback have been recorded in high elevation forests. Mn pollution was emphasized due to its large emission from gasoline combustion in Canada. Airborne Cu, Mn, V, and Zn showed higher concentrations than those reported for other remote locations. Significant fluctuation in Mn concentrations during the winter-spring season was explored by air mass back trajectory analysis. The study suggested that high Mn concentrations resulted from the atmospheric long-range transport from Canadian industrialized and metropolitan regions. Metal concentrations in podzolic topsoils were generally higher than their world-wide average values. Concentrations of trace metals in balsam fir (Abies balsamea (L.) Mill) needles were below their suggested potential phytotoxic levels, except for Mn, which also increased with elevation. The scanning of needles with micro-PIXE showed no significant correlation between metal accumulation and epistomatal distribution on foliar surfaces.
Pathways of trace metals deposited in the soil-tree system were elucidated through application of $ sp{54}$Mn and $ sp{65}$Zn on shoot, bark, and soil surfaces in growth-chamber experiments with balsam fir seedlings. Uptake and accumulation by seedlings 70 days after application on the shoot surface was about 25-30% of the remaining activities for $ sp{54}$Mn and $ sp{65}$Zn. Less than 1% of absorbed isotopes was translocated from the bark surface to other plant organs, whereas more than 50% of the radioisotopes absorbed at the shoot moved to the rest of the seedling. Acidic wetness facilitated the metal absorption through tree surfaces. Downward movement of the radioisotopes in podzolic soils was documented, and accumulation in seedlings by root uptake was 5% of the remaining activity for $ sp{54}$Mn and 3% for $ sp{65}$Zn 70 days after application. No appreciable elemental migration from internal tissues to epicuticular wax layers was found, and the leaching ratio was below 0.5 and 1.0% for $ sp{54}$Mn and $ sp{65}$Zn, respectively. This study helps to understand the links between atmospheric deposition and the elevated levels of Mn in trees, and potential effects of acid deposition on the bioaccumulation of toxic metal pollutants in high elevation forests in southern Quebec.

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Nkqenkqa, Vuyiseka. "Metal and microbial contamination of agricultural soil and the Veldwachters River, Stellenbosch, South Africa." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2423.

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Thesis (MTech (Environmental Health))--Cape Peninsula University of Technology, 2017.
Surface water is used as a source of water supply in many countries, including South Africa. One of the sources of surface water pollution is leachate and surface runoff from landfills. In agricultural soils, the landfill runoff and leachate deteriorate the quality and affect the fertility of soil. The entry of metals and microorganisms from landfill leachate to adjacent environments is through surface runoff due to rainfall. Adverse effects on human- and environmental health triggers a need to monitor and control contaminants in the environment. The aims of the study are to determine the effect of landfill runoff and leachate on agricultural soil and river water (Veldwachters River) running adjacent to the Devon Valley landfill site and to identify potential metal-tolerant organisms in environmental samples collected in Stellenbosch, Western Cape, South Africa. Samples (agricultural soil, river water and sediments) were collected once a month for a period of six months from the study area for analysis. Physicochemical parameters that are known to have major effects on environmental samples were assessed and the concentrations of various metals (Al, Pb, Cr, Mn, Mo, Co, Ni, Cu, Zn, Fe, Cd and V) were also determined by means of inductively coupled plasma mass spectrometry (ICP-MS). Soil texture analysis was tested in order to monitor the metal distribution in soils under the influence of environmental factors.

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Sandifer, Richard D. "The effects of cadmium, lead and zinc contamination on arthropod communities in the vicinity of a primary smelting works." Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339519.

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Burton, Susan Mary. "Evaluation of stream meiofauna as a monitor of trace metal contamination." Thesis, University of Plymouth, 1998. http://hdl.handle.net/10026.1/2168.

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Members of the meiobenthos have been used extensively to determine the effects of anthropogenic perturbation in marine systems (Coull & Chandler, 1992). Despite this, the meiofauna has been virtually excluded from freshwater pollution monitoring. This thesis aimed to address this research caveat, by evaluating the potential of stream meiofauna for monitoring metal-contamination. Meiofaunal communities were sampled from streams in SW England representing a gradient in metal contamination. Environmental variables in these streams were also measured to identify the important forcing agents structuring the stream benthos. Multivariate techniques demonstrated Cu, either alone or in combination with other environmental variables was of most importance in correlations with the composition of meiofaunal communities. Comparison with the macrofaunal data demonstrated that both components of the benthos responded in a similar way to metal contamination, although the meiofauna also highlighted other differences in water chemistry. The combination of meiofauna, macrofauna and temporary meiofauna in a combined metazoan community analysis gave the best discrimination of sites. Detection of metal-contamination was retained in meiofaunal data aggregated to the family level. The abundances of the harpacticoid copepod Bryocamptus zschokkei were consistently important in contributing to between-site differences in community structure. The harpacticoid, therefore was selected as an ecologically-relevant freshwater toxicity test for Cu. Laboratory experiments demonstrated that Cu had toxic effects on the survival and reproduction of Bryocamptus zschokkei. Although acute toxicity tests gave more rapid results, these effects on survival occurred at a higher Cu concentration than those in the chronic tests. Sub-lethal concentrations of Cu led to a reduction in the numbers of offspring per brood Animals with pre-exposure to chronic concentrations of Cu exhibited greater tolerance to this metal. In conclusion, more information may be gained by including the meiofauna, alongside the macrofauna, when monitoring the impact of contaminants on freshwater systems. To reduce the effort of processing samples it appears family level data could be used to detect metal-contamination. The novel use of B. zschokkei in laboratory tests, where it showed lethal and sub-lethal responses to Cu, demonstrated that this species may have much potential as an ecologically-relevant freshwater bioassay organism for this metal. The advantages of using meiofaunal species such as B. zschokkei as toxicity test organisms are discussed.

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16

Sarin, Charoon. "A lux-based bioassay of heavy metal contamination of organic wastes." Thesis, University of Aberdeen, 2000. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU123515.

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The luxCDABE genes (i.e. full cassette) were inserted into the bacterial strain used in this study, E. coli HB101, using a multi copy plasmid, (pUCD607). A number of experiments were carried out in this thesis to study the potential of using the biosensor, E. coli HB101 (pUCD607), for ecotoxicity testing. Growth and bioluminescence of E. coli HB101 (pUCD607) were characterised and optimised, as well as the stability of this biosensor to a range of environmental parameters. The biosensors were found to be sensitive to a range of pollutants and provided a highly consistent bioluminescence response under conditions likely to be encountered in environmental toxicity testing. Assessment of the potential of the lux-based bioassay for revealing the combination of toxicities of metals was carried out. This is necessary because samples in ecotoxicity testing may contain a number of types of pollutants. The biosensors showed high sensitivity of response to mixed metals and identified the combined toxicity of the mixture. Biosensor bioluminescence could also be used to diagnose the distinction between toxicity after 15 and 30 minutes exposure. Results suggested that exposure time is an important factor affecting on the toxicity of metals in mixtures. The results from challenging lux-based biosensors with heavy metals with various concentration of Cl- demonstrated the effect of Cl- ion complex formation for metals on the bioluminescence of E. coli HB101 (pUCD607). The bioluminescence response of the biosensor also related to the results from computer modelling (GEOCHEM) and was used to diagnose the effect of Cl- on metal toxicity. The results showed that E. coli HB101 (pUCD607) is sensitive to complexes of metals such as are formed by Cl- ion. Immobilised cells of E. coli HB101 (pUCD607) were used to investigate the toxicity of metals, both singly and in mixture. This work aimed to assess the potential of immobilised cells, as an alternative form of biosensor, for use in ecotoxicity testing. Bioluminescence response of immobilised cells varied with the test solution pH and showed that it has great potential for use in low pH environments. Immobilised cell biosensors demonstrated sufficient sensitivity to identify the toxicity of individual and mixed metals. High levels of bioluminescence of immobilised cells lasted up to 5 hours after bead production, suggesting that biosensor immobilisation increases the flexibility of the toxicity assay.

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17

Karapanagiotis, Nicolas Konstantine. "Heavy metal retention by the organic fraction of sewage sludge." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342264.

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Ginnever, Rhoda C. "Soil and plant contents of lead and other trace elements with special reference to the influences of parent rock and pollution." Thesis, Aberystwyth University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324309.

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19

Mamboya, Florence Alex. "Heavy metal contamination and toxicity : Studies of Macroalgae from the Tanzanian Coast." Doctoral thesis, Stockholm : Department of Botany, Stockholm University, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-6818.

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20

Challa, Swapnika. "Metal contamination and methane oxidising bacteria around a formerly industrialised suburban river." Thesis, Sheffield Hallam University, 2015. http://shura.shu.ac.uk/19438/.

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Heavy metal pollution is a very prominent problem persisting globally at the present time. Many technologies have been put forward to remediate such pollution. Bioremediation is a promising and eco-friendly tool to resolve environmental pollution. Microbes belonging to diverse phylogenetic groups have been investigated previously for remediation and immobilisation of pollutants. One among such groups are methanotrophs, which grow on methane as their sole source of carbon and energy and are able to remediate diverse hydrophobic organic pollutants due to the wide range of substrates utilised by their oxygenase enzymes. Recently, it was shown that the methanotroph Methylococcus capsulatus (Bath) was also able to remediate hexavalent chromium contamination. In the current study sediment samples were enriched from an urban river in Sheffield in Northern England that has previously suffered serious heavy metal pollution due to previous activity of the steel industry (17th to 19th century). The site selected for the present study was the River Sheaf located on south west of Sheffield in Northern England and approximately 3 miles from city centre, and which flows from Totley through Millhouses Park. Sediment samples were collected and characterised, according to various size fractions and then heavy metal analysis was carried out in the various fractions of the sediments. The most abundant heavy metals found at site were lead, chromium, nickel, arsenic and cobalt. The maximum concentrations of the heavy metals Pb, Cr, Ni, As and Co in the site were 412.80 mg/kg, 25.232 mg/kg, 25.196 mg/kg, 8.123 mg/kg and 7.66 mg/kg, respectively. Methanotrophs were enriched and isolated from the Sheaf sediments and then the isolated methanotrophs were investigated to determine their ability to reduce the hexavalent chromium. A strain of Methylomonas koyamae, which was given the strain designation SHU1, was isolated and found to remove hexavalent chromium across a range of concentrations in the range of 10-1000ppm after cultivation on methane as growth substrate. The Cr (VI) may be reduced to Cr (III) but the production of Cr (III) was not experimentally investigated and so there is the possibility that some or all of the chromium removal could be due to biosorption and uptake into the cells e.g. via the sulphate transport pathway. It was also found that the removal of Cr (VI) was inhibited by the addition of the metabolic inhibitor sodium azide, thus indicating that removal of chromium is largely a metabolic reaction mediated by enzymes rather than a passive biosorption process. It was speculated that methane monooxygenase (MMO) provides electrons from the oxidation of methane which may be used by other enzymes for removal (e.g. chemical reduction) of hexavalent chromium. Phenyl acetylene is a strong inhibitor of soluble MMO (sMMO) but inhibits particulate MMO (pMMO) less effectively. When cells expressing sMMO and pMMO were inhibited by phenyl acetylene the chromium removal reaction was completely inhibited compared in cells expressing sMMO. The above isolated organism produces a sMMO when there is copper deficiency in the media which is another distinguishing characteristic to potentially apply the organism in bioremediation of hydrophobic organic compounds, because sMMO generally has a wider substrate range than pMMO. The proteins encoded by available genome sequences of Methylomonas strains were compared with proteins from other microbes that are involved in chromium reduction, efflux systems and chromium uptake. Highly significantly similar proteins were found in the Methylomonas strains which resembled the proteins known to be involved in chromium removal, uptake and reduction. A number of strains of the Methylomonas genus are known to possess a gene for the sulphate transporter systems which could also play a major role in transportation of chromium (VI) into the cells. To the author's knowledge this is the first description of a strain of the widely environmentally distributed genus Methylomonas that is capable of remediating hexavalent chromium.

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Shuping, Likentso Sylvia. "Biomonitoring of metal contamination in the lower Diep River, Milnerton, Western Cape." Thesis, Cape Peninsula University of Technology, 2008. http://hdl.handle.net/20.500.11838/786.

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Thesis (MTech (Environmental Health))--Cape Peninsula University of Technology, 2008
The lower Diep River is a major freshwater ecosystem in the Western Cape. The river is surrounded by many possible sources of metal pollution such as an oil refinery, industries, a sewage treatment plant and a landfill site. However, metal contamination levels have not been monitored in this river. The aim of the study was therefore to monitor the degree of metal pollution in the lower Diep River, over a period of one year, and to investigate the use of the sedge Bolboschoenus maritimus, as biomonitor species. Three sampling sites were used. Site I was located in the vicinity of landfill sites and farm areas. Site 2 was located I km upstream from a wetland reserve, surrounded by heavy industrial activity and continuous residential developments. Site 3 was located downstream of the wetland reserve, 2 km from the river mouth. The following metals were investigated: aluminium, cadmium, chromium, cobalt, copper, iron, lead, manganese, nickel and zinc. Water and sediment samples were collected every two months for a period of one year. Plant specimens (roots, leaves and stems) were collected seasonally from site I and site 3. Samples were acid digested and metal analysis was done using an ICP - AES (Inductively Coupled Plasma- Atomic Emission Spectrophotometer). Statistical analyses were done to investigate possible differences between the sites, sampling occasions and various plant components.

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Adediran, Gbotemi Abraham. "Role of plant growth promoting bacteria and a leguminous plant in metal sequestration from metal contaminated environments by Brassica juncea." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/10523.

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The worldwide occurrence of sites contaminated with toxic metals and the associated high costs of remediating them using chemical and mechanical methods have led to calls to develop inexpensive and sustainable approaches based on the use of plants that naturally accumulate large amounts of metals in their tissues. The ability of plants to remediate metals has been rigorously studied and some species have been identified as excellent phytoremediators. However, the growth of phytoremediators is often retarded under high soil metal concentrations, rendering them ineffective. Meanwhile, some plants do not have remediating abilities but are capable of growing in contaminated environments with little or no sign of stress. Despite the volume of research dedicated to the screening and evaluation of phytoremediators, major questions remain about why some plants survive but do not remediate while the growth of phytoremediators is mostly hindered. The growth and metal-remediating efficiency of plants exposed to toxic concentrations of metals can be enhanced by inoculating phytoremediating plants with certain bacteria but the mechanisms behind this process remain unclear. Furthermore, the use of leguminous plants to improve the growth of a target plant under a mixed planting system has long been recognised as an effective yield-enhancing cropping system. However, the possibility of a non-remediating but tolerant leguminous plant conferring metal tolerance to a phytoremediator has not been explored. This thesis reports results from repeated glasshouse and lab-based growth experiments on the phytoremediating plant Brassica juncea exposed to 400 – 600 mg Zn kg-1. The aim was to investigate the abilities of two plant growth promoting bacteria (PGPB) species Pseudomonas brassicacearum and Rhizobium leguminosarum, and a leguminous plant Vicia sativa to promote B. juncea growth and enhance remediation of Zn-contaminated soil. B. juncea plant roots were analysed using synchrotron based micro-focus X-ray Fluorescence (μXRF) imaging and X-ray Absorption Near Edge Structure (μXANES) analysis to probe Zn speciation. P. brassicacearum exhibited the poorest plant growth promoting ability, while R. leguminosarum alone and in combination with P. brassicacearum significantly enhanced B. juncea growth and Zn bioaccumulation. X-ray Absorption Spectroscopy (XAS) analysis showed that reduced plant growth was due to root accumulation of Zn as Zn sulphate, Zn oxalate and Zn polygalacturonic acids. The better growth and increased metal accumulation observed in plants inoculated with R. leguminosarum and its combination with P. brassicacearum was attributed to root storage of Zn in the chelated forms of Zn phytate and Zn cysteine. A subcellular analysis of plant root also showed that the PGPB enhanced tolerance to Zn contamination by enhancing epidermal Zn compartmentalisation depending on the nature of root colonization, and induced changes in Zn speciation to less toxic Zn species in the epidermis and endodermis of plant root. The thesis therefore identifies enhanced Zn compartmentalization at the root epidermis and bacterial mediated changes in Zn toxicity through changes in Zn speciation as key complimentary mechanisms of plant growth promotion and enhanced Zn accumulation in plants by PGPB. Further experiments investigating alternative phytoremediation strategies showed that the use of the leguminous plant V. sativa in a mixed planting system with B. juncea plants completely out performed the effects of bacteria in promoting the growth and remediation potential of B. juncea under Zn contamination. By combining PGPB with mixed planting, B. juncea recovered full growth while also achieving maximum phytoremediation efficiency. The novel legume assistedmicrobial phytoremediation method that is reported in this thesis is the first to demonstrate complete plant growth recovery in plants exposed to 400 – 450 mg kg-1 soil Zn contamination for 5 weeks. Survival of V. sativa was attributed to its root storage of Zn in the chelated forms of Zn histidine and cysteine whereas in the roots of stunted B. juncea plants the majority of Zn was present as Zn oxalate and toxic Zn sulphate. Although the use of natural and synthetic chelates has been reported to enhance phytoremediation, this thesis recommends a legume-assisted-microbialphytoremediation system as a more sustainable method for Zn bioremediation.

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23

Redfern, Farran Mack. "Heavy Metal Contamination from Landfills in Coastal Marine Sediments: Kiribati and New Zealand." The University of Waikato, 2006. http://hdl.handle.net/10289/2323.

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Landfill leachates are a concern in the Pacific Region where they may contribute contaminants to the coastal marine environment. Poor waste management and pollution of coastal waters are amongst the major environmental problems in Kiribati, particularly in South Tarawa. An investigation of areas adjacent to coastal landfill sites; Betio, Kiribati and Auckland, New Zealand was undertaken. The Kiribati case study investigated metal contamination in marine sediments at an operational landfill while the New Zealand study was adjacent to a coastal landfill decommissioned in the 1970s. Surficial sediments (top 15 cm) were collected along transects. At both the New Zealand and Kiribati sites, 3 transects adjacent to the landfill and 1 control transect were sampled. The sediments were analyzed for particle size distribution, organic matter content, and Cd, As, Cr, Cu, Pb, Hg, Ni and Zn concentrations. The pH was also measured. The Kiribati study site had a groundwater pH of 7.14 - 8.85, and sediment materials were dominated by sand with a low organic matter content (1.60 - 2.21 %). At the Kiribati sites Cd, As, and Ni were below the detection limits. The Cr, Cu, Pb and Zn concentrations were lower at the Kiribati control transect than the landfill transects. Cr level decreased away from the landfill indicating the landfill as a possible source. However, Cu and Zn did not show any distribution pattern suggesting other potential sources (port and shipwrecks) may have contributed to the elevated levels. At the Kiribati landfill and control transects the Cr, As, Cd, Cu, Pb, Ni, and Zn concentration were below the Effects Range-Low (ERL) and the threshold Effects levels (TEL) of the Sediment Quality Guidelines (SQCs) of the National Oceanographic and Atmospheric Administration (NOAA) and the Florida Department of Environmental Protection, indicating no potential adverse ecological effects on the biota. At the Kiribati control site the Cr, As, Cd, Cu, Pb, Ni and Zn concentrations were within the background ranges published for clean reef sediment but the concentration at the landfill transects exceeded the background ranges. The concentration of mercury at both the control and landfill transects in Kiribati exceeded the Effects Range-Median (ERM) and the Probable Effects Level (PEL) of the SQGs indicating potential adverse ecological effects on the local benthic communities. The New Zealand study site sediments had a pH of 6.22 - 7.24, and comprised up to 90 % clay/silt, with an organic matter content of 5 - 22 %. At the New Zealand landfill transects Arsenic concentrations decreased away from the landfill indicating the landfill as a possible source. Other metals such as Cr did not show a pattern of distribution along the transects, or with depth, suggesting that the landfill was not the only source of these metals. There was a weak correlation between organic matter content, particle size distribution, and metal enrichment. At the New Zealand site, there were no marked differences in metal concentrations between the landfill and control transects suggesting the landfill was not the only source of metals and that the wider urban or industrial run-off may have contributed. All the metal concentrations, except Hg and Zn, exceeded the ERL and the TEL values indicating the potential for adverse ecological effects of metals on the benthic communities. At the New Zealand site the Hg and Zn concentrations exceeded both the ERM and PEL of the SQGs and are considered highly contaminated.

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24

Van, Loon Gabriel. "Levels of trace metal contamination in selected stormwater BMPS and potential ecotoxic impacts." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0022/MQ31264.pdf.

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25

Buckby, Tracy. "Processes of persistent metal contamination in the RiÌo Tinto, south west Spain." Thesis, University of Reading, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428101.

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26

Costenla, Mariana Mascarenhas de Menezes. "Heavy metal contamination in seafood and consumer exposure in the Gulf Cooperation Council." Master's thesis, Faculdade de Ciências e Tecnologia, 2014. http://hdl.handle.net/10362/13156.

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Dissertação para obtenção do Grau de Mestre em Tecnologia e Segurança Alimentar
The population from countries surrounded by the Gulf and Arabian Sea depend on fisheries. Industry is growing and discharges by desalination plants and refineries lead to the presence of heavy metals which accumulate in the environment and seafood. The aim is to review seafood contamination with cadmium, arsenic, lead and mercury in Saudi Arabia, Oman, Kuwait, United Arab Emirates, Bahrain and Qatar and estimate the consumer exposure to these metals. All samples of molluscs and crustaceans tested for arsenic (As) showed concentrations above maximum permitted levels, Qatar and UAE being the most contaminated. All samples from Kuwait contained lead (Pb), cadmium (Cd) and mercury (Hg). Bahrain samples contained Pb above permitted levels. On the coast of Oman and Qatar shellfish showed concentrations of Cd above permitted levels. The EWI for As from shellfish is above the PTWI for all samples. For Cd, all except shellfish from Oman, Bahrain and KSA entail a EWI above the PTWI. None of the samples, except from Kuwait, provide Pb above the PTWI and for Hg, only the clam, mussel and crab contain higher amounts. Four locations in the UAE contained fish with Cd above permitted levels. Tuna fish from KSA had higher levels of Cd and Pb. Highest levels of Hg could be found in fish from Kuwait. Bahrain and Qatar showed the highest levels of As. Hg EWI exceeded for the UAE, Kuwait and Qatar. Estimated weekly intakes of As and Cd from shellfish are extremely high and above the Provisional Tolerable Weekly Intake. Fish from these countries does not contain high levels that pose a threat to public health, except for As. The risk is probably in chronic low exposure. Risk groups should be properly advised.

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27

Mdzeke, Naomi Patience. "Contamination levels in and cellular responses of intertidal invertebrates as biomarkers of toxic stress caused by heavy metal contamination in False Bay." Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/53733.

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Thesis (PhD) -- Stellenbosch University, 2004.
ENGLISH ABSTRACT:Heavy metals are persistent environmental contaminants whose sources of inputs into the environment are both natural and anthropogenic. The levels of heavy metals (cadmium, copper, nickel, lead and zinc) in the False Bay intertidal zone were measured in the water, sediments and invertebrate species between August 2000 and August 2001. The results of the water and sediment analyses revealed that most pollution was associated with the northern shore of the bay between Strand and Muizenberg, where the most populated and industrial catchments occur. Significant spatial variations occurred, indicating the presence of localised contamination, while seasonal variations may be related to changes in precipitation and runoff at different times of the year. The concentrations of cadmium, nickel and lead were occasionally higher than the levels recommended by the South African Water Quality Standards. The possible sources of pollution at the different sites are also discussed. The concentrations of the five metals in the different invertebrate species (Oxystele tigrina, 0. sinensis, Choromytilus meridionalis, Patella oculus, Patiriella exigua and Tetraclita serrata) also revealed significant seasonal and spatial variations, with both the soft tissues and shells accumulating heavy metals. The barnacle T serrata from Rooiels had the highest cadmium concentration (70.67 J.lg/g dry weight), which may be related to historic pollution inputs from the military activities which took place at a weapons testing site at this site between 1987 and 1994, although no evidence was found to confirm this. The periwinkle 0. tigrina from Strand had the highest copper concentration (70.25 J.lg/g) while the limpet P. oculus from the same site had the highest nickel concentration (35.75 J.lg/g). The shells of the mussel C. meridionalis from Muizenberg had the highest concentration of lead (25.75 J.lg/g). Since cadmium occurs as a constituent of phosphate fertilisers used widely in the False Bay catchments, the effects of cadmium exposure on the different species were investigated during 14-day laboratory exposures to 200 and 400 J.lg/LCdCh. The results revealed a general pattern of tissue metal increase in the exposed organisms, followed by slight reductions after decontamination in clean seawater. The viscera and kidneys of C. meridionalis accumulated most of the dissolved cadmium. The shells of the mussels also accumulated cadmium, indicating the possible use of shells as a detoxification matrix.
AFRIKAANSE OPSOMMING:Swaarmetale is persisterende omgewingskontaminante waarvan die insetbronne beide natuurlik of van menslike oorsprong kan wees. Die kontaminasievlakke van swaarmetale (kadmium, koper, nikkel, lood en sink) in die Valsbaai tussengetysone is in die water, sedimente en invertebraatspesies bepaal vanaf Augustus 2000 tot Augustus 2001. Voorlopige resultate van die water- en sedimentontledings het getoon dat die meeste besoedeling by die noordelikke oewer van die baai voorgekom het tussen Strand and Muizenberg, waar die mees digbewoonde en ge-industrialiseerde opvangsgebiede is. Betekenisvolle ruimtelike en seisoenale variasie het in die konsentrasies van swaarmetale voorgekom, met die ruimtelike variasie wat moontlik gelokaliseerde kontaminasie aandui terwyl die seisoenale variasies weer verband mag hou met veranderings in die neerslag en afloop gedurende verskillende tye van die jaar. Die konsentrasie van kadmium, nikkel en lood was somtyds hoer as die vlakke wat deur die Suid-Afrikaanse Waterkwaliteitsstandaarde voorgestel word. Die moontlike bronne van besoedeling in die verskillende areas is ook in bespreking genoem. Die konsentrasies van die vyf swaametale in die verskillende invertebraatspesies (Oxystele tigrina, 0. sinensis, Choromytilus meridionalis, Patella oculus, Patiriella exigua and Tetraclita serrata) het ook seisoenale en ruimtelike variasies vertoon, die swaarmetale het in die sagte weefsel en skulpe van die invertebrate geakkumuleer. Die hoogste gemiddelde konsentrasie van kadmium (70.67 ).lg/g droe massa) is in die heel-liggaam monsters van die eendemossel T serrata gemeet wat by Rooiels versamel is. Die vlakke mag verband hou met die oprigting en aktiwiteite van die wapentoetsingsaanleg in die opvanggebied van die Rooiels lokaliteit tussen 1987 en 1994, maar geen bewyse daarvan is gevind nie. Die tolletjie, 0. tigrina wat in die 10kaliteit by Strand versamel is het die hoogste gemiddelde konsentrasie koper gehad 70.25 pig droe massa), terwyl die klipmossel P. oculus by dieselfde versamelpunt die hoogste konsentrasie nikkel (35.75 ).lg/gdroe massa) gehad het. Eksperimentele studies is ook uitgevoer op vier invertebraat spesies wat vir 14 dae in akwaria blootgestel is aan see-water met 200 en 400 p,g/L CdCh, en daama gedekontamineer is in skoon seewater.
The NRF and the University of Stellenbosch, for funding this study.

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Hooda, Partap Singh. "The behaviour of trace metals in sewage sludge-amended soils." Thesis, Queen Mary, University of London, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343892.

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29

Geffard, Alain. "Reponses du biota a la contamination polymetallique d'un milieu estuarien,la gironde ,fr : exposition, impregnation, induction d'une proteine de detoxication, la metallothioneine, impact au niveau individuel et populationnel.(doctorat ecotoxicologie)." Nantes, 2001. http://www.theses.fr/2001NANT11VS.

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30

Whitfield, Lynn. "Heavy metal tolerance and mycorrhizal colonisation in Thymus polytrichus A. Kerner ex BorbaÌs ssp. britannicus (Ronn.) Kerguelen (Lamiaceae)." Thesis, University of Newcastle Upon Tyne, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246685.

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31

Haring, Peter G. "The nature of heavy metal contamination in organic lake sediments near the Buchans massive sulphide base metal mines, Central Newfoundland /." Internet access available to MUN users only, 2002. http://collections.mun.ca/u?/theses,25133.

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32

Otomo, Patricks Voua. "Stress responses of Eisenia andrei and Enchytraeus doerjesi (Oligochaeta) to combined effects of temperature and metal contamination." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/6900.

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Thesis (PhD)--Stellenbosch University, 2011.
ENGLISH ABSTRACT: The terrestrial Oligochaete species Eisenia andrei and Enchytraeus doerjesi were exposed to different concentration series of Cd and Zn, both separately and in mixtures for 28 days in artificial OECD soil at 15, 20 and 25°C. At the end of the four week exposure period, survival and reproduction were assessed in E. doerjesi and survival, reproduction, biomass change, metal uptake and biomarker responses (MTT and comet assays) in E. andrei. Survival results for both E. andrei and E. doerjesi indicated that the lethality of Cd increased at higher temperatures, whereas the opposite was observed for Zn.Cadmium LC50 values were the highest at 15°C and the lowest at 25°C. In the Zn exposures LC50 increased with increasing temperature. Mixture results in both test organisms indicated that mixtures were less lethal than the metals separately. Effects of mixtures on survival, nonetheless, increased with increasing temperature. In the Cd experiment, reproduction in E. andrei was only recorded in the control treatments at the three temperatures investigated. However, the deleterious effect of Zn on the reproduction of both E. andrei and E. doerjesi decreased with increasing temperature and Zn EC50 for reproduction increased with increasing temperature. Results for exposures to mixtures indicated in both test organisms that the interaction between Cd and Zn were antagonistic. In both E. andrei and E. doerjesi, the effect of mixture exposures on reproduction decreased with increasing temperatures. The highest mixture EC50 values for reproduction were found at higher temperature. In E. doerjesi (using reproduction results in MixToxModules) Cd and Zn interactions were dose level dependent at the three temperatures investigated. Antagonism was the predominant interaction at lower mixture concentrations whereas synergism occurred at mixture concentrations equal to or higher than the mixtures’ EC50 values. Biomass loss increased with increasing temperature in the Cd exposures (p 9 0.05) but not in the Zn exposures in E. andrei. In this species mixture results indicated antagonistic interactions between Cd and Zn at all temperatures investigated. The deleterious effect of mixtures on the biomass of E. andrei increased with increasing temperature. When Cd and Zn interactions were further investigated in E. andrei (using biomass results in MixToxModules) it was found that they were dose level dependent at the three temperatures investigated. Antagonism was the predominant interaction at lower mixture concentrations whereas synergism occurred at mixture concentrations higher than the mixtures EC50 values. The assessment of metal uptake in E. andrei revealed a temperature dependent Cd uptake with higher Cd body burdens occurring at higher exposure concentrations and temperatures (p ≤ 0.05). In the case of Zn, although uptake was lower at higher temperature, there was no statistical difference in uptake between exposure concentrations and between temperatures. Mixture results however indicated that in mixture exposures less Cd was accumulated by E. andrei than in single Cd exposures (p ≤ 0.05). Inversely, in mixture exposures more Zn was accumulated by E. andrei than in single Zn exposures (p ≤ 0.05). Biomarker studies revealed that Cd and Zn were both cytotoxic and genotoxic whether in single or mixture exposures. Factorial ANOVA analyses of the effects of temperature and metals on the reduction of MTT by E. andrei indicated that temperature rather than the metals was the most important factor controlling mitochondrial activity (p < 0.001). In both Cd and Zn exposures significant deleterious metal effects on mitochondrial processes were found to increase with temperature (p ≤ 0.01). Mixture exposures indicated decreasing cytotoxicity with increasing temperature (p ≤ 0.05) and possible antagonism between Cd and Zn at cellular level. Results of the comet assay showed that the genotoxic profile of Cd was the opposite of the genotoxic profile of Zn. Cd was less genotoxic at lower temperature and increasingly deleterious at higher temperature while Zn was more genotoxic at lower than higher temperature (p ≤ 0.05). The results of mixture exposures indicated decreasing mixture genotoxicity with increasing temperature and suggested that the interactions between Cd and Zn at molecular level were probably antagonistic.
AFRIKAANSE OPSOMMING: Eisenia andrei en Enchytraeus doerjesi is aan verskillende konsentrasiereekse van Cd en Zn, afsonderlik en in mengsels, vir 28 dae in OECD kunsmatige grond onderskeidelik by 15, 20 en 25°C blootgestel Die volgende eindpunte is aan die einde van die vier weke blootstellingsperiode gemeet: oorlewing en voortplanting (by E. doerjesi) en oorlewing, voortplanting, biomassaverandering, metaalopname, MTT en komeettoetse (by E. andrei). Oorlewingsresultate by beide E. andrei en E. doerjesi het getoon dat toenemende temperatuur die letale toksisiteit van Cd laat toeneem terwyl die teenoorgestelde waar was vir Zn. By die Cd blootstellings was die LK50 waardes die hoogste by 15°C en die laagste by 25°C. By die blootstellings aan Zn het die LK50 waardes toegeneem by hoër temperatuur. Resultate by die mengsels by beide toestspesies het aangetoon dat die mengsels minder letaal was as die afsonderlike metale. Effekte van mengsels op oorlewing het nietemin toegeneem met toenemende temperatuur. By die Cd blootstellings is voortplanting slegs by die kontroles en in die geval van E. andrei by die drie onderskeie temperature ondersoek. Die nadelige uitwerking van Zn op voortplanting by beide E. andrei en E. doerjesi het afgeneem met stygende temperatuur en die Zn LK50 vir voortplanting het toegeneem met toenemende temperatuur. Resultate van die blootstellings aan mengsels het getoon dat die wisselwerking tussen Cd en Zn by beide spesies antagonisties was. By beide spesies het die invloed van die mengsels op voortplanting afgeneem met stygende temperatuur. Die hoogste mengsel LK50 waardes vir voortplanting is by hoër temperature gevind. By E. doerjesi was Cd en Zn wisselwerkings by blootstelling aan mengsels (voortplantingsresultate ondersoek deur van MixToxModules gebruik te maak) dosisvlak verwant by die drie temperature wat ondersoek is. Antagonisme was die oorwegende wisselwerking by laer mengsel konsentrasies terwyl sinergisme voorgekom het by mengsel konsentrasies gelyk aan of hoër as die LK50 waardes van die mengsels. In die geval van die Cd blootstellings by E. andrei het biomassaverlies toegeneem met toenemende temperatuur (p ≤ 0.05) maar nie by die Zn blootstellings nie. Resultate van blootstellings aan mengsels het getoon dat die uitwerking van mengsels op die biomassa van E. fetida toegeneem het met toenemende temperatuur. By die verdere ondersoek van Cd en Zn wisselwerkings, waar gekyk is na dosis verhouding of dosisvlak antagonisme (deur van biomassa resultate in MixToxModules gebruik te maak), is gevind dat Cd en Zn wisselwerkings dosisvlak afhanklik was by die drie temperature wat ondersoek is. Antagonisme was die oorwegende wisselwerking by laer mengselkonsentrasies terwyl sinergisme voorgekom het by mengselkonsentrasies hoër as die mengsel EK50 konsentrasies. Die bepaling van metaalopname deur E. andrei het ’n temperatuurafhanklike opname van Cd getoon met hoër Cd liggaamskonsentrasies by hoër blootstellingskonsentrasies en temperature (p ≤ 0.05). Alhoewel Zn opname laer was by hoër temperatuur was daar geen statisties betekenisvolle verskille in opname tussen blootstellingskonsentrasies of temperature nie. Die bepaling van metaalopname by wurms wat aan mengsels blootgestel is, het getoon dat minder Cd deur E. andrei opgeneem is as waneer die wurms aan Cd as enkelmetaal blootgestel is (p ≤ 0.05), Daarteenoor het die teenoorgestelde gebeur in die geval van Zn, Meer van die metaal is opgeneem wanneer E. andrei aan mengsels blootgestel is as aan die enkelmetaal. Biomerkerstudie het getoon dat Cd en Zn beide sito- en genotoksies kan wees ongeag of dit as enkelmetale of in mengsels toegedien is. Faktoriale ANOVA analises van die effekte van temperatuur en metale op die verlaging van MTT by E. andrei het getoon dat temperatuur ’n belangriker faktor was as metaalbesoedeling by die kontrole van mitochondriale aktiwiteit. (p ≤ 0.001). By beide Cd en Zn blootstellings was daar in elk geval statisties betekenisvolle metaaleffekte op mitochondriale prosesse met toename in temperatuur (P ≤ 0.01). By blootstellings aan mengsels is gevind dat sitotoksisiteit afgeneem het met toenemende temperatuur (p ≤ 0.05) asook ’n moontlike antagonisme tussen Cd en Zn op sellulêre vlak. Resultate van die komeettoets het getoon dat die genotoksiese profiel van Cd die teenoorgestelde was as die van Zn. Cd was minder genotoksies by laer temperature en meer en meer skadelik by hoër temperature terwyl Zn meer genotoksies was by laer as by hoër temperature (p ≤ 0.05). Die resultate van blootstlling aan mengsels het laer genotoksisiteit getoon met toename in temperatuur. Dit dui daarop dat wisselwerkings tussen Cd en Zn op molekulêre vlak moontlik antagonisties was.

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Cebrian, Pujol Emma. "Sublethal effects of heavy metal contamination on marine sponges: Responses at different biological levels." Doctoral thesis, Universitat de Barcelona, 2007. http://hdl.handle.net/10803/805.

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Many antrophic activities release pollutants to the marine environment. Among them heavy metals are of great importance, since they are conservative pollutants, which can be accumulated through trophy chains. Sometimes, the liberation to the marine waters is acute and drastic, leading to massive mortalities. However, more often, the liberation is by means of low and chronic concentrations. The main objective of the present thesis is to analyze the sponge responses in face to sublethal concentrations of heavy metals and to determine, if it is possible, whether they can be used as biomonitors of such kind of pollution. First, we have studied their availability to accumulate havey metals in both, temporal and especial scales. And then, by means of the use of different biomarkers, to analyze the sublethal effects of heavy metals on sponges at different levels of biological organization, from molecules to populations. The present thesis has been performed by means of experiments in situ and at the laboratory, in order to elucidate heavy metal accumulation patterns and their effects depending on the specie and metal considered.
TÍTOL DE LA TESI: "Efectes subletals de la contaminació per metalls pesats en esponges marines: Respostes a diferents nivells d'organització".

TEXT:

Moltes activitats antròpiques alliberen contaminants en el medi. Entre els contaminants hem de destacar els metalls pesants, ja que són contaminants conservatius y que s'acumulen a través de les xarxes tròfiques. En alguns casos la alliberació dels contaminants en el medi es dona de forma aguda i dràstica, el què pot provovar mortalitats massives. De totes formes, de forma general l'alliberació al medi dels metalls pesants es dóna a baixes concentracions i de forma crónica. L'objectiu principal d'aquesta tesis és analitzar les respostes de les esponges a concentracions subletals de metalls pesants i determinar la seva utilitat com a biomonitors d'aquest tipus de contaminació. En primer lloc, s'ha d'estudiar la capacitat de les esponges per acumular metalls pesants tant a una escala temporal com espaial. En segon lloc, mitjançant l'ús de diferents biomarcadors, analitzar els efectes subletals dels metalls en les esponges, a diferents nivells d'organització biológica, desde les molècules fins a les poblacions. Aquesta tesis s'ha dut a terme mitjançant experiments que convinen aproximacions in situ i en el laboratori per tal de compendre de millor maners els models d'acumulació i els seus efectes en funció de l'espècie i el metall considerat.

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Gorenc, Shelley Anne. "Heavy metal contamination of surficial tidal flat sediments in the Yangtze River Estuary, China." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ61896.pdf.

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Swanton, Kerry Vivienne. "Food safety and waste water reuse : heavy metal contamination in peri-urban Varanasi, India." Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428327.

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Korre, Anna. "A methodology for the statistical and spatial analysis of soil contamination in GIS." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266111.

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Plathe, Kelly Lee. "Nanoparticle - Heavy Metal Associations in Riverbed Sediments." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/26229.

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Relationships between trace metals and nanoparticles were investigated using analytical transmission electron microscopy (aTEM) and asymmetric flow field flow fractionation (aFlFFF) coupled to both multi-angle laser light scattering (MALLS) and high resolution-inductively coupled plasma mass spectroscopy (HR-ICPMS). Riverbed sediment samples were taken from the Clark Fork River in Montana, USA where a large-scale dam removal project has released reservoir sediment contaminated with toxic trace metals (namely Pb, Zn, Cu and As) which accumulated from one and a half centuries of mining activities upstream. An aqueous extraction method was used to attempt to separate the nanoparticles from the bulk sediment. After analysis of initial results, it was found that low density clays were being selected for in this process and made up a major portion of the particles within the extracts. However, it was also realized that the metals of interest were associated almost exclusively with nano-sized Fe and Ti oxides. In order to more fully examine these relationships, a density separation method, using sodium polytungstate (2.8g/cm3), was developed to separate these higher density oxides from the lower density clays. The heavy fraction was then subjected to an aqueous extraction routine to extract the nanoparticulate fraction. FFF results indicated a smaller size distribution and more ideal fractionation with this method. The aFlFFF-HR-ICPMS profiles for Fe and Ti also matched strongly with the data for the trace metals. The majority of particles analyzed with the TEM were nano-sized Fe and Ti oxides (most commonly goethite, ferrihydrite and brookite), which typically had trace metals associated with them. In many cases, it was aggregates of these nano oxides that were found hosting trace metals. Nanoparticles and aggregates are known to behave differently than their bulk mineral phases or constituent particles, respectively. Nanoparticles are also capable of extended transport in the environment. For these reasons, it is important that their associations with toxic trace metals be extensively evaluated, as they will affect the bioavailability and toxicity of these metals with implications for any type of contaminant sediment relocation, dam removal or metal contaminated site.
Ph. D.

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Xiangdong, Li. "The study of multielement associations in the soil-plant system in some old metalliferous mining areas, England." Thesis, Imperial College London, 1993. http://hdl.handle.net/10044/1/7803.

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Saunders, Graham R. "The effects of copper on marine meiobenthic communities : field and laboratory studies." Thesis, Heriot-Watt University, 2000. http://hdl.handle.net/10399/1231.

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Bunker, Adrian John. "The impact of the oil industry on subtidal meiobenthos." Thesis, Heriot-Watt University, 1999. http://hdl.handle.net/10399/1269.

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Arshad, Aziz. "Temporal and spatial responses of benthic communities and populations across upper estuarine environmental gradients." Thesis, University of Plymouth, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284365.

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42

Souza, José Ivanildo de. "Mucorales de solo contaminado com metais pesados na região do pólo cerâmico de Santa Gertrudes, SP : ocorrência e capacidade de biossorção de chumbo e zinco /." Rio Claro : [s.n.], 2006. http://hdl.handle.net/11449/103975.

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Orientador: Iracema Helena Schoenlein-Crusius
Banca: Carmen Lidia Amorim Pires-Zottarelli
Banca: Sandra Farto Botelho Trufem
Banca: Dejanira de Franceschi de Angelis
Banca: Carlos Renato Corso
Resumo: Em solo contaminado com metais pesados na região do pólo cerâmico do município de Santa Gertrudes, Estado de São Paulo, Brasil, foi realizado o levantamento taxonômico de fungos da ordem Mucorales (Zygomycota) utilizando-se o método da placa-de-solo, modificado pela aplicação de uma suspensão de solo (10%, p v-1) sobre malte agar (2%, p v-1) acrescido de Pb(NO3)2 ou Zn(NO3)2 nas concentrações de 0 (controle), 100, 200, 500 e 1000 mg L-1. As identificações e descrições taxonômicas foram realizadas utilizando-se SMA (synthetic Mucor agar), sendo obtidos os táxons: Absidia cylindrospora v. cylindrospora Hesselt. & Ellis, Cunninghamella phaeospora Boedijn, Mucor circinelloides Tiegh. f. circinelloides, M. circinelloides Tiegh. f. lusitanicus (Bruderl.) Schipper, M. circinelloides Tiegh. f. janssenii (Lendn.) Schipper, Mucor hiemalis Wehmer f. hiemalis, M. hiemalis Wehmer f. luteus (Linnem.) Schipper, Mucor racemosus Fresen. f. racemosus, Rhizopus oryzae Went & Prins. Geerl., Zygorrhynchus moelleri Vuill. e Mucor bainieri Mehrotra & Baijal, que é citado pela primeira vez para o Brasil. Análises químicas de amostras de solo coletadas em quatro locais na área estudada confirmaram a contaminação severa por metais pesados em alguns dos locais, sendo que comparações entre o número de táxons obtidos no presente estudo com os dados de literatura permitiram concluir que houve prejuízo à diversidade de fungos na região. As biomassas secas e pulverizadas (2 g L-1) de Mucor hiemalis f. hiemalis (SPC 2040) e de Mucor hiemalis f. luteus (SPC 2044) foram colocadas em contato, sob agitação a 120 rpm por 14 h, com soluções aquosas (pH 4) de Pb(NO3)2 e Zn(NO3)2 nas concentrações de 0,06, 0,13 e 0,17 mM e de 0,08, 0,16 e 0,23 mM, respectivamente, sendo comparadas ao carvão ativado (CA), utilizado como material adsorvente de referência
Abstract: In a heavy metal contaminated soil at ceramic pole of Santa Gertrudes region, São Paulo State, Brazil, a taxonomic survey of fungi of the order Mucorales (Zygomycota) have been done using the soil plate method, modified for a soil suspension (10%, p v-1) application on malt agar (2%, p v-1) added with Pb(NO3)2 or Zn(NO3)2 at 0 (control), 100, 200, 500 and 1000 mg L-1 concentrations. Taxonomic identifications and descriptions have been done with SMA (synthetic Mucor agar), obtaining the taxa: Absidia cylindrospora v. cylindrospora Hesselt. & Ellis, Cunninghamella phaeospora Boedijn, Mucor circinelloides Tiegh. f. circinelloides, M. circinelloides Tiegh. f. lusitanicus (Bruderl.) Schipper, M. circinelloides Tiegh. f. janssenii (Lendn.) Schipper, Mucor hiemalis Wehmer f. hiemalis, M. hiemalis Wehmer f. luteus (Linnem.) Schipper, Mucor racemosus Fresen. f. racemosus, Rhizopus oryzae Went & Prins. Geerl., Zygorrhynchus moelleri Vuill. and Mucor bainieri Mehrotra & Baijal, that is cited first time for Brazil. Chemical analyses of soil samples taken from four sites in the studied area confirm a severe contamination of heavy metals in some of the sites, and comparisons between taxa numbers obtained in the present study with literature data allowed conclude that there was fungal diversity disturbance in the region. The dry and grounded biomasses (2 g L-1) of Mucor hiemalis f. hiemalis (SPC 2040) and Mucor hiemalis f. luteus (SPC 2044) was kept in contact, under agitation at 120 rpm during 14 h, with aqueous solutions (pH 4) of Pb(NO3)2 and Zn(NO3)2 at 0.06, 0.13, 0.17 mM and 0.08, 0.16, 0.23 mM concentrations, respectively, being compared with activated charcoal (AC) as the reference adsorbent. The percentages amounts of metals removed from solutions, express by q% index, had presented the following adsorption sequences: AC > SPC 2044 > SPC 2040 for Pb and AC > SPC 2040 > SPC 2044 for Zn
Doutor

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43

Simpson, Julia Marie. "Effects of heavy metal contamination on burial rates of Austrovenus stutchburyi implications for sediment transport /." The University of Waikato, 2009. http://hdl.handle.net/10289/2766.

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Urbanisation in coastal catchments has significantly increased not only the input of terrestrial sediment to the marine environment but also the input of contaminants. In Tamaki Estuary, Auckland, heavy metals have accumulated in the upper estuarine muddy sediments and metal contamination has been detected on downstream intertidal sandflats. Sub-lethal levels of heavy metal contamination may affect the growth and behaviour of benthic organisms, which in turn may influence key ecosystem processes and productivity. The aim of this study was to examine whether the burial rate of an ecologically important bivalve species (Austrovenus stutchburyi) differed between a contaminated and a lesser-contaminated site and whether burial rates were affected by density. A secondary aim was to determine whether the burial of Austrovenus affected sediment transport and consequently if this was affected by density. This study demonstrated no consistent difference in burial time between source populations (sites). This was explained by a lack of measured difference in the condition index and heavy metal tissue loading of Austrovenus used throughout this study. The present range of contamination measured in Tamaki Estuary, Auckland, did not have negative biological consequences on the key ecosystem engineer, Austrovenus stutchburyi. Contamination levels in Tamaki Estuary may not be high enough to cause major physiological or behaviour changes to infaunal organisms, such as Austrovenus. Sediment erodability was not significantly correlated with any measured environmental and biotic factors. Austrovenus density was the only predictor variable that could be used to explain any variation in sediment erodability. There was no significant density effects observed between the amounts of sediment eroded for densities gt; 150 ind. m-2. There was a significant difference between sediment void of Austrovenus (0 ind. m-2; smooth, flat undisturbed sediment surface) and sediment containing Austrovenus (gt;150ind. m-2; physical structure on/in the sediment surface, increase in bed roughness). These results indicate that there is little or no effect of Austrovenus on the critical erosion threshold, suggesting that in the absence or presence of Austrovenus the current required to erode 10 g m-2 of sediment would remain somewhere between 28.5 and 30.5 cm s-1. This study found that there was considerable variation in the burial rate of individuals and the greatest variation was recorded in the lowest density treatments (150 ind. m-2), which corresponded to the same density that had the greatest variation in sediment erodability. Further investigations are needed to gain a better understanding into the important roles (the importance of the various feedbacks and limitations and interrelationships) that Austrovenus play in the soft-sediment ecosystem, as losses of this species are likely to have large-scale impacts on the wider soft-sediment communities and ecosystem functioning.

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Eastwood, Shawn. "Effects of environmental metal contamination on the condition of northeastern Ontario yellow perch (Perca flavescens)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq61265.pdf.

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45

Barak, Najim A.-E. "Aspects of biology and heavy metal contamination of eels and roach in East Anglia rivers." Thesis, University of Essex, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.328860.

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46

PORTELLA, CRISTIANE MARIA DE MELLO ALVES. "EVALUATION OF THE POSSIBILITY OF CONTAMINATION OF SEA WATER BY METAL IONS PRESENT IN OIL." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2005. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=6942@1.

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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
Com a probabilidade de ocorrer derrames de óleo em águas marinhas e a carência de informação sobre o comportamento de metais neste evento, viu-se a necessidade de se intensificar estudos referentes aos complexos metálicos, para que se possa entender a competição entre os ligantes do petróleo e os ligantes da água do mar. Para isto é necessário determinar a estabilidade dos complexos formados no petróleo, compará-los com os correspondentes na água do mar. Neste trabalho foram estudados os sistemas binários de complexos de ácido hexanóico (ligante que representa os ácidos carboxílicos do petróleo) e 1-propanotiol (representante das mercaptans) com os íons metálicos de interesse para a indústria do petróleo - Ni(II), V(IV) e Fe(II) - por estarem presentes em maior quantidade. Embora presentes em menor quantidade, Cd(II) e Pb(II) foram estudados por serem metais tóxicos e controlados pelas organizações ambientais. O ácido hexanóico apresenta o oxigênio do grupamento carboxilato, como sítio de coordenação enquanto que o 1-propanotiol possui o enxofre do grupamento tiol. O estudo da complexação foi realizado em solução utilizando a titulação potenciométrica e a espectrofotometria de ultravioleta- visível, Foram calculadas as constantes de dissociação dos ligantes e de formação dos complexos ML, ML2, ML3, MLOH, ML(OH)2, ML(OH)3, ML2OH, ML2(OH)2, ML3OH. Os valores das constantes de estabilidade dos complexos poderiam ser divididos em dois grupos: o dos complexos binários com ácido hexanóico e os complexos binários do 1- propanotiol. Dos complexos formados com o ácido hexanóico, a espécie ML com o íon metálico Pb(II) foi que apresentou maior estabilidade. No sistema onde temse complexos com 1-propanotiol, a espécie ML do íon metálico Cd(II) foi o que apresentou maior estabilidade. Na distribuição de espécies com ligantes representantes do petróleo e ligantes da água do mar observou-se a formação de complexos em pH = 7 para os íon metálicos V(IV), Ni(II) e Fe(II) com o ácido hexanóico. Para o íon metálico Pb(II) o complexo formado foi com o 1- propanotiol. Já para o íon Cd(II) houve a formação de complexo com o cloreto. Para o íon Cd(II), neste pH houve formação de pouca proporção de complexos com 1-propanotiol e um percentual maior (60 por cento) de complexos com os íons cloreto e sulfato da água do mar. Entretanto, como a concentração de cádmio é em torno de ppb no óleo combustível, este valor tem pouca relevância em termos de poluição. Assim, se estes ligantes estudados, que são monodentados, ligam-se preferencialmente aos metais do que os ligantes da água, com certeza isto acontece com os ligantes polidentados do petróleo como por exemplo as porfirinas. Com a utilização da técnica de espectrofotometria de ultravioletavisível foi possível observar as bandas referentes a transferência de carga e banda d-d. Foi realizada também uma simulação de derrame de óleo combustível. Para isto analisou-se a concentração de metais foi medida em tempos variados. Os dados teóricos e da simulação confirmam que íons metálicos ficam retidos no óleo mesmo quando há derrame do óleo na água do mar.
In face of the probability of occurrences of oil spill in marine waters and the lack of information concerning the behavior of the metals in such events, it is necessary to intensify the studies of metal complexes in order to understand the competition between oil ligands and sea water ligands. For such, it is necessary to determine the stability of the complexes formed in oil and compare them with the correspondent ones in sea water. In the present work the binary systems of the complexes of hexanoic acid (a ligand that represents the carboxylic acids of the oil) and 1-propanethiol (which represents the mercaptans) with the metal ions of interest to the petroleum industry - Ni(II), V(IV) and Fe (II) - were studied because they are present in greater quantities. Despite being present in smaller quantities, Cd(II) and Pb(II) were also studied because they are toxic and controlled by environmental organizations. Hexanoic acid has an oxygen atom of the carboxylate group as donor atom, and 1-propanethiol has a sulfur atom of the thiol group. The complexation study was performed in solution using potentiometric titration and ultraviolet-visible spectrophotometry. The dissociation constants of the ligands and the formation constants of the complex species ML, ML2, ML3, MLOH, ML(OH)2, ML(OH)3, ML2OH, ML2 (OH)2 and ML3(OH) were calculated. The values of the stability constants can be divided in two groups: one with the binary complexes of hexanoic acid and the other with the binary complexes of 1-propanethiol. Among the complexes formed with hexanoic acid, the ML species with metal ion Pb(II) was the most stable. In the system of the complexes with 1-propanethiol, the ML species with Cd(II) was the most stable. In the species distribution as a function of pH including the representative ligands of oil and sea water, it could be observed that at pH =7 the most stable species for the metal ions V(IV), Ni(II) and Fe (II) were those with hexanoic acid. In relation to ion Pb(II) the complex formed was with 1- propanethiol. Cd(II), this pH occurred the formation of a small proportion of the complex with 1-propanethiol and a higher percentual (60 percent) of the complexes with the chloride and sulfate íons of sea water. Since the concentration of Cd(II) is in the range of ppb, this metal ion is less relevant when pollution is concerned. Thus, if the monodentate oil ligands studied in this work preferably bind metal ions rather than sea water ligands, than this certainly happens with the polydentate oil ligands such as porphyrins. Using the ultraviolet-visible spectrophotometry technique it was possible to observe the charge transfer bands and the d-d bands. A simulation of oil dispersion was also performed and the concentration of the metals was measured at various times. Both theoretical and simulation data showed that the metal ions are retained in the oil, even when the oil is spread in sea water.

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47

Thuong, Nguyen Thi. "Heavy Metal Contamination in Water and Sediment of To Lich River in Inner City Hanoi." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/180494.

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MA, JUN. "Risk Assessment and Sequestered Contamination Evaluation for Legacy Heavy Metal Contaminants in Cleveland Area Brownfields." Case Western Reserve University School of Graduate Studies / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=case1106351960.

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Nussle, Sean Brian. "TRICHOPTERAN LARVAE AS BIOMONITORS OF TRACE AND HEAVY METAL CONTAMINATION IN NORTHEAST OHIO URBAN STREAMS." Kent State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=kent1534960377604447.

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Maxwell, Deborah. "REMEDIATION OF HEAVY METAL CONTAMINATION IN SEDIMENTS: APPLICATION OF IN SITU TREATMENT UTILIZING EMULSIFIED LIQUID MEMBRANE AN." Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4329.

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Abstract:

Heavy metal contamination of soils, sediments and groundwater presents an ongoing source of hazardous and persistent environmental pollution. How best to remediate these contaminants is the impetus of continuing research efforts. Methods include containment, ex situ and in situ techniques. A successful in situ method utilizing a combination of emulsified liquid membranes, ELM, and zero-valent metal, ZVM, and bimetals has demonstrated impressive heavy metal reduction in 100 ppm solutions of Cd, Cu, Ni, Pb, Cr and U. This promising in situ method has been employed by the Industrial Chemistry Laboratory at the University of Central Florida and it has demonstrated considerable success in treating several environmental threats. Contaminated soils, surfaces, sediments and groundwater with offending agents such as trichloroethene, polychorobiphenyls and heavy metals have been treated utilizing emulsified liquid membrane systems containing zero-valent iron or bimetal particles. In vial studies, lead spiked sediments have shown repeatable 60% removal of lead after seven days of treatment. A persistent pattern emerged at ten days whereupon remediation levels began to drop. The current study was established to determine the reason for the decline at ten days and beyond. Questions addressed: Does the formation of an impeding oxide layer diminish the remediation capacity of the iron/magnesium system? Does the emulsion reach a maximum capacity to withdraw the contaminant? Do the soil components or the soil structure interfere with the access to the contaminant? This study has yielded insight into the reasons emulsified liquid membrane systems containing zero-valent metals achieved maximum lead removal at day seven, and thereafter begin to lose their effectiveness. A three part study was implemented to address and to answer the three questions pertaining to the consistent pattern of diminishing remediation levels exhibited at day ten and beyond. Initially, from Study I results it appeared that the formation of an impeding oxide layer on the bi-metal which was inside the emulsion droplet and which plated or precipitated with the lead was not occurring at day ten. Results indicated that the iron/magnesium was still capable of removing lead. Furthermore, from Study II results the emulsion dose injected appeared adequate to remove the lead, meaning that the emulsion had not reached its maximum capacity for remediation. The emulsion dose was not a limiting factor. Lastly, Study III results seemed to indicate that the drop in remediation after day seven pertained to the soil structure. There appeared to be some merit to the idea that with aging of the sediment, the lead was diffusing and migrating to some inaccessible interior sites within the sediment particles. Additionally, indications from day ten and day fourteen delineated that a second emulsion dose injection might restore lead removal levels to approach those first observed at day seven and consequently be a useful field application. In order to explore the effectiveness of injecting a second dose of emulsion, another vial study was implemented. The typical pattern of observing sixty percent maximum lead removal at day seven was observed. In separate groups, a second injection of emulsion was added at day five, and then for another vial series, a second dose was added at day seven. The second emulsion dose treatment for either day five or day seven did not yield any increases in percent lead removal. Another theory emerged after viewing micrographs of recovered iron/magnesium compared with fresh ball-milled bimetal. In addition, scanning electron microscopy appeared to confirm the explanation that the emulsified zero-valent metal system might be compromised after day seven. This would lead to exposure of the iron/magnesium to the air and the elements. Corrosion of the bimetal might be occurring. With time, release of the plated or precipitated lead back into the sediment mixture could follow. The results of Study I had led to the conclusion that an impeding oxide layer had not formed; however, this conclusion may have been premature because the recovered iron/magnesium was exposed to lead solution in the vial study. Perhaps if the recovered iron/magnesium was inserted back into an emulsion and injected into lead spiked sediments the percent lead removed might give a more accurate picture of the iron/magnesium's capability to continue performing remediation. Remediation of sediments contaminated with lead is a complicated task because of the complex nature of sediment components. Emulsified liquid membranes utilizing zero-valent bimetals has repeatedly demonstrated impressive results at day seven; however, this treatment method is not without its limitations. Optimal results appear to be gained at day seven after emulsion injection. The bimetal and plated or precipitated lead must be removed at that point; otherwise the effective remediation of the contaminant is progressively reversed.
M.S.
Department of Chemistry
Sciences
Industrial Chemistry MS

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