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1
Claus, Sonia Carmel, University of Western Sydney, of Science Technology and Environment College e of Science Food and Horticulture School. "Heavy metals in biota from temperate Australian estuaries". THESIS_CSTE_SFH_Claus_S.xml, 2003. http://handle.uws.edu.au:8081/1959.7/503.
Testo completoAbstract (sommario):
The detection of anthropogenic impacts in our estuaries has become a critical social, political and scientific concern in recent years. Work has focussed on the effects of these impacts on the spatial and temporal patterns of biotic assemblages and searched for bioindicators and biomarkers of pollutants that may act as early warning signs. The estuaries in temperate Southeastern Australia have a diversity of biotic assemblages living in the soft sediment. One of the most abundant macroinvertebrates is the little studies mussel, Xenostrobus securi that is found living with an assemblage of benthic biota including amphipods, crabs, isopods and tanaids, bivalves and gastropods. Two commercial fish species bream and mullet also inhabit these estuaries. Numerous stormwater drains can be found entering the estuaries through the mangrove forests lining the shores. Along with inputs of freshwater, stormwater drains are thought to be responsible for the entry of heavy metals into estuaries. These heavy metals have the potential to alter the patterns of biotic assemblages and bioaccumulate in the tissues of miacroinvertebrates, mussels and fish living within temperate estuaries. Over the time of this study the concentrations of heavy metals in the sediment tissues and shell of X.Securis varies spatially and temporally. Although this study adds substantially to current knowledge there is still more that is needed to establish X. Securis as a bioindicator. Questions remain about uptake, depuration and response to environmental gradients of heavy metals in X. Securis. Before X Securis can be used routinely in monitoring heavy metal contamination these questions need to be further investigatedDoctor of Philosophy (PhD)
2
Leung, Siu Ying. "Accumulation of DDTs, heavy metals and PBDEs in fish collected from fish ponds and mariculture zones of the Pearl River Delta, China". HKBU Institutional Repository, 2008. http://repository.hkbu.edu.hk/etd_ra/880.
Testo completo
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Martinez, Maria L. 1960. "Organochlorine Pesticides and Heavy Metals in Fish From the Trinity River, Texas". Thesis, University of North Texas, 1990. https://digital.library.unt.edu/ark:/67531/metadc500474/.
Testo completoAbstract (sommario):
The Trinity River passes through the Dallas-Fort Worth metroplex receiving point and non-point source contaminant loadings. Lepomis spp. were collected at twelve sampling locations in the Trinity River in August 1987 and September 1988 and analyzed for organochlorine pesticides and heavy metals. Results from the study were compared to existing U.S. FDA action and tolerance levels, LC50s, and historical data. Various longitudinal trends and some concentration patterns were observed. Continual study of pesticide and metal body burdens in fish allow testing for trends, and thereby, lead to a better understanding of the distribution of contaminants in the Trinity River.
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Johnson, Adam Nicholas. "Toxicological Comparison of Heavy Metal Salt and Semiconductor Nanoparticle Exposure in Zebrafish (Danio rerio)". Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/JohnsonAN2007.pdf.
Testo completo
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Zhou, Hai Yun. "Evaluation of organochlorines and heavy metals in the Pearl River Delta and Hong Kong, with emphasis on bioaccumulation in freshwater fish". HKBU Institutional Repository, 1999. http://repository.hkbu.edu.hk/etd_ra/207.
Testo completo
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Adijaya, Mardan. "The effects of humic water, heavy metals and parasitism on freshwater teleost fish in West Kalimantan, Indonesia". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ35466.pdf.
Testo completo
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Sherwood, Graham D. "Fish energetics in polluted ecosystems". Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=38280.
Testo completoAbstract (sommario):
Conventional wisdom in ecotoxicology predicts reductions in organismal fitness to follow from exposure-related physiological effects. This expectation may be appropriate for controlled laboratory environments, but may not necessarily reflect what is likely to take place in the wild. In an extensive review of the ecotoxicology literature, it was revealed that fish condition factor (an index of energetic fitness) is just as likely to respond favourably to pollutant exposure as it is to respond negatively. The remainder of this thesis examines some of the ecological reasons for this apparent paradox. One possible cause of altered energetic status in wild, pollutant-exposed fish is variable food availability. Addressing this possibility, I showed that consumption rates (estimated using a 137Cesium mass-balance approach) were not related to growth reductions in hormonally-impaired yellow perch ( Perca flavescens) from metal-contaminated lakes. Another possibility is that fish forage less efficiently in metal-polluted lakes as a result of lowered prey choice. In this thesis, I develop an enzymatic and individual-based biomarker for fish activity costs (muscle lactate dehydrogenase, LDH, activity) and show, through the use of this tool that the cost of fish activity is intimately tied to prey type and the ability to make normal ontogenetic diet shifts. Through the application of LDH measurements, as well as through bioenergetic modelling, diet and prey community analyses, a link between decreased prey choice and high perch activity costs leading to zero growth efficiency (energetic bottlenecks) was demonstrated in yellow perch from metal-contaminated lakes. This finding provided one of the first examples in ecotoxicology of a mechanistic link between community and organismal endpoints. The findings of this thesis emphasize the need for ecotoxicology to consider ecology when looking for and interpreting ecologically relevant endpoints. The final chapter of this thesis ex
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Merciai, Roberto. "Effects of global change on fish assemblages in Mediterranean streams". Doctoral thesis, Universitat de Girona, 2016. http://hdl.handle.net/10803/405192.
Testo completoAbstract (sommario):
L'objectiu d'aquesta tesi és de'explorar alguns aspectes de l'impacte humà sobre les poblacions de peixos i altres components dels ecosistemes fluvials Mediterranis de Catalunya. Es va mostrar com els peixos del Riu Llobregat acumulen quantitats significatives de metalls pesants, amb concentracions en el múscul que varien al llarg del riu i segons l'espècie i la talla dels peixos. En el Riu Tordera, afectat per l'extracció d'aigua, el règim de temperatures es veu alterat en correspondència dels trams intermitents, en els quals la probabilitat de supervivència i l'abundancia dels peixos , i en menor mesura el creixement i la condició corpòria, també pateixen les conseqüencies de l'alteració hidrològicaThe goal of this thesis is to explore some aspects of anthropogenic impact on the fish populations and other components of two Mediterranean stream ecosystems in Catalonia NE Spain). It was shown how Llobregat River's fish accumulate significant trace metal quantities, with muscle concentrations varying across sampling sites along the river, fish species and size. In the Tordera Stream, affected by water abstraction, the temperature regime was disrupted in correspondence of the intermittent reaches, where fish abundance and survival probability and, at a lower extent, growth and body condition, also suffered the consequences of hydrologic alteration
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Andreikėnaitė, Laura. "Genotoxic and cytotoxic effects of contaminants discharged from the oil platforms in fish and mussels". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2010. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2010~D_20101102_153642-57785.
Testo completoAbstract (sommario):
Aquatic ecosystems are still being polluted with crude oil and other technogenic contaminants. In order to evaluate genotoxic and cytotoxic impact of this pollutants, micronucleus test and analysis of the other nuclear abnormalities is rather frequently being used. The main objective of the study is assessment of genotoxicity and cytotoxicity effects in different fish and bivalves exposed to the crude oil and other technogenic contaminants discharged from the several oil platforms (Statfjord B, Oseberg C, Minija).
Environmental genotoxicity and cytotoxicity was evaluated by measuring the frequencies of micronuclei and other nuclear abnormalities in cells of mussels and fish caged in different oil platforms (Ekofisk, Statfjord B) field zones in situ. The study results provide new information about environmental geno-cytotoxicity in oil platforms field zones. The peculiarities of genotoxicity and cytotoxicity in fish and mussels after experimental treatment with crude oil from the North Sea oil platforms and Minija well in Lithuania and other technogenic contaminants (produced water, mixtures of PAHs, alkylphenols and heavy metals) were assessed. There were determined time-tissue-species-concentration-related relationships in induction of nuclear abnormalities in studied fish and mussels. The study results revealed usefulness of genotoxicity endpoints, as well as cytotoxicity endpoints for the evaluation of damage, caused by the contamination discharged from the marine oil... [to full text]Į vandens ekosistemas patenka dideli kiekiai žaliavinės naftos bei naftos išgavimo technologinių procesų metu susidarančių teršalų. Šiame darbe analizuotas Šiaurės jūroje veikiančių naftos platformų (Statfjord B, Oseberg C), Barenco jūroje išgaunamos arktinės bei Lietuvoje esančio Minijos naftos gręžinio žaliavinės naftos, taip pat skirtingų gamybinių vandenų atskiedimų, įvairių poliaromatinių angliavandenilių ir alkilfenolių bei sunkiųjų metalų mišinių genotoksinis (pagal mikrobranduolių ir branduolio pumpurų dažnius) bei citotoksinis (pagal fragmentuotų-apoptozinių ir dvibranduolių ląstelių dažnius) poveikis skirtingų rūšių moliuskų ir žuvų ląstelėse. Taikant aktyvaus monitoringo metodą nustatytas Statfjord B ir Ekofisk naftos platformų aplinkos genotoksiškumas ir citotoksiškumas in situ. Šio darbo tyrimų rezultatai suteikė naujos informacijos apie naftos platformų aplinkos geno-citotoksiškumą, taip pat skirtingose platformose išgaunamos žaliavinės naftos, gamybinių vandenų, įvairių alkilfenolių, sunkiųjų metalų mišinių geno-citotoksinį poveikį vandens organizmams. Atlikti tyrimai leido įvertinti genotoksiškumo ir citotoksiškumo dėsningumus skirtingose organizmų grupėse ir jų audiniuose. Eksperimentų metu nustatyta skirtingų žaliavinės naftos, alkilfenolių, sunkiųjų metalų mišinių skirtingų koncentracijų, ekspozijos laiko bei geno-citotoksiškumo indukcijos priklausomybė. Darbe aprašyti metodai gali būti sėkmingai naudojami monitoringe kaip ankstyvieji biožymenys įvairių... [toliau žr. visą tekstą]
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Van, Look Katrien Jo Warda. "The development of sperm motility and morphological techniques for the assessment of the effects of heavy metals on fish reproduction". Thesis, University of Sheffield, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369940.
Testo completo
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Barst, Benjamin Daniel. "Hepatotoxicity of Mercury to Fish". Thesis, University of North Texas, 2010. https://digital.library.unt.edu/ark:/67531/metadc31525/.
Testo completoAbstract (sommario):
Tissue samples from spotted gar (Lepisosteus oculatus) and largemouth bass (Micropterus salmoides) were collected from Caddo Lake. Gar and bass livers were subjected to histological investigation and color analysis. Liver color (as abs at 400 nm) was significantly correlated with total mercury in the liver (r2 = 0.57, p = 0.02) and muscle (r2 = 0.58, p = 0.01) of gar. Evidence of liver damage as lipofuscin and discoloration was found in both species but only correlated with liver mercury concentration in spotted gar. Inorganic mercury was the predominant form in gar livers. In order to determine the role of mercury speciation in fish liver damage, a laboratory feeding study was employed. Zebrafish (Danio rerio) were fed either a control (0.12 ± 0.002 µg Hg.g-1 dry wt), inorganic mercury (5.03 ± 0.309 µg Hg.g-1 dry wt), or methylmercury (4.11 ± 0.146 µg Hg.g-1 dry wt) diet. After 78 days of feeding, total mercury was highest in the carcass of zebrafish fed methylmercury (12.49 ± 0.369 µg Hg.g-1 dry wt), intermediate in those fed inorganic mercury (1.09 ± 0.117 µg Hg.g-1 dry wt), and lowest in fish fed the control diet (0.48 ± 0.038 µg Hg.g-1 dry wt). Total mercury was highest in the viscera of methylmercury fed zebrafish (11.6 ± 1.86 µg Hg.g-1 dry wt), intermediate in those fed inorganic diets (4.3 ± 1.08 µg Hg.g-1 dry wt), and lowest in the control fish (below limit of detection). Total mercury was negatively associated with fish length and weight in methylmercury fed fish. Condition factor was not associated with total mercury and might not be the best measure of fitness for these fish. No liver pathologies were observed in zebrafish from any treatment.
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Ebrahimi, Mansour. "Effects of pollution on steroidogenesis and sperm in fish". Thesis, University of Sheffield, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389736.
Testo completo
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Wainaina, Steven. "Effect of heavy metals on syngas fermentation". Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-10203.
Testo completoAbstract (sommario):
The goal of this work was to establish the suitable and limiting concentrations of Zn, Cu and Mn compounds during syngas fermentation. The results showed that cells encased in polyvinylidene difluoride (PVDF) membranes had a faster accumulation of methane in reactors containing fermentation medium dosed with 5 mg/L of each heavy metal compared to free cells. It was also revealed that total inhibition of biohydrogen production occurred in medium containing 5 mg/L Cu, 30 mg/L Zn and 140 mg/L Mn while the most suitable metal concentration level was 0.1 mg/L Cu, 0.6 mg/L and 2.8 mg/L Mn. In addition, a comparison test showed that for the most suitable metal concentration in the medium, rate of performance at pH 6 and 7 was higher than at pH 5.
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Claus, Sonia Carmel. "Heavy metals in biota from temperate Australian estuaries /". View thesis, 2003. http://library.uws.edu.au/adt-NUWS/public/adt-NUWS20051013.092820/index.html.
Testo completoAbstract (sommario):
Thesis (Ph.D.) -- University of Western Sydney, 2003."Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy at the University of Western Sydney Hawlesbury" Bibliography : leaves 245-278.
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Morris, Thomas Colin. "Fish parasites as bio-indicators of heavy metals in two South African embayments". Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/15608.
Testo completoAbstract (sommario):
The Cape Elephant fish (Callorhinchus capensis) and two common sand shark species (Rhinobatos annulatus and Rhinobatos blochii) were caught off False Bay and Saldanha Bay and surveyed for their parasite community in 2013 and 2014. The surveys were used to build species accumulation curves (SAC) and calculate biodiversity indices, particularly, rarefied species richness, Shannon Weiner's diversity index, Simpson's index and Pielou's J index. The biodiversity indices were correlated with the host's biological data and parasite infection data, to determine the parasite community structure and provide insight into the host's community structure. The parasites identified in C. capensis (n=19) include a cestode (Gyrocotyle plana), two monogeneans (Callorhynchicotyle callorhynchi and Callorhinchicola multitesticulatus) and an isopod (Anilocra sp.). The cestode was the most prevalent at 68.4 % and the monogenean, C. callorhynchi was the most abundant (1.68 ±0.78) and had the highest infection intensity (4.00 ±1.45). The SAC and biodiversity measures indicate a uniform parasite community across the host population, suggesting a highly interactive shark community. Conversely, Rhinobatos annulatus (n=19) and R. blochii (n=17) had very limited parasite infection with two species of nematode found infecting the stomach (Proleptus obtusus) and encysted in the kidneys (Ascaris sp.) and a copepod species (Clavelottis sp.) found infecting the gills. Proleptus obtusus was the most prevalent (31.6 % and 29.4%), the most abundant (1 ±0.37 and 3.68 ±2.76) and had the highest mean infection intensity (3.17 ±0.4 and 14 ±1.5). A cestode (Trilocularia sp.) was found infecting three specimens of R. annulatus from False Bay. The SAC and biodiversity indices combined with the limited parasite infection indicate a non-uniform parasite community across the host population, suggesting an isolationist population. Within the parasite community discovered, a potential biological indicator for heavy metal accumulation was identified to determine the levels of heavy metal pollution within these two anthropogenically impacted bays. Gyrocotyle plana and Proleptus obtusus were chosen as potential indicators due to their high prevalence and the close relationship they have with their hosts. The results support the use of higher trophic level animals as biological indicators. The results also indicate that G. plana is an incredibly good accumulator of certain metals, particularly As (4073.52 ± 5561.54 μg/g), Mn (522.16 ± 578.21 μg/g), Pb (64.87 ± 101.7 μg/g), Ti (1821.42 ± 1348.16 μg/g), and Zn (12439.57 ± 9743.60 μg/g). Unfortunately water and sediment samples were not tested, however, concentrations were compared to baseline values, and the accumulation of these metals are orders of magnitude above the surrounding environment. Proleptus obtusus did not significantly accumulate metals from its surrounding environment. These results show that parasites can be used to infer their own and their host's community structure and confirm their usefulness as indicators of pollution in marine ecosystems.
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Omar, F. A. "The effect of heavy metals on growth of marine phytoplankton". Thesis, Swansea University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638366.
Testo completoAbstract (sommario):
A study has been made on the effect of zinc, calcium and copper on the growth and 14C fixation of Phaeodactylum tricornutum and Dunaliella primolecta. Experiments were carried out to examine the uptake of 65Zn by Phaeodactylum and Dunaliella in laboratory culture, to investigate the processes involved, its relationship to metabolism, and the factors affecting it. Also, experiments were carried out to investigate the effect of these metals on chlorophyll concentration and protein content of Phaeodactylum and Dunaliella. It has been found that the organisms displayed varying degrees of tolerance to the presence of the metals zinc, cadmium and copper in the growth medium. Of the three metals copper was found to be more effective upon the growth, 14C fixation, zin-65, chlorophylla concentration and protein content of Phaeodactylum and Dunaliella.
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Salah, Sharif Ali. "Heavy metals uptake by wheat under two transpiration rates". Thesis, McGill University, 2001. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33838.
Testo completoAbstract (sommario):
The present project aimed at measuring plant heavy metal uptake as a function of transpiration rates and dissolved heavy metal level in the soil solution. Two experiment was conducted separately in two season (Spring and Fall 2000). In these two experiments, young wheat plants ( Triticum aestivum) were irrigated with nine different solutions containing Cd and Zn. The study was conducted in two chambers where relative humidity was controlled to obtain two different levels of transpiration rates. Each control chambers contained 27 pots filled with sand and seeded with wheat plants, each nine triplicated pots receiving a different treatment: three Cd treatments with levels of 0.01, 0.10, and 0.50 mg/L; one Zn treatment with level of 25mg/L and four treatment combinations of Cd/Zn with levels of 0.01 Cd/25Zn, 0.10Cd/25ZN, 0.50Cd/25Zn and 0.50Cd/50Zn mg/L. The transpiration rate of the plants was monitored over a period of 30 days, measured from the emergence of the plants by weighing the pots daily. On day 15 and 30, three plants were removed from each pot, to weigh their dry matter production and to analyze their heavy metal uptake. (Abstract shortened by UMI.)
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Roach, John Paul. "Trace Metals in Fish From a Reservoir Receiving Runoff From a Developing Watershed". Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/40820.
Testo completoAbstract (sommario):
The objective of this research was to measure the concentrations of the cadmium, chromium, copper, lead, mercury and zinc in bass and carp taken from the Occoquan Reservoir in Virginia with three purposes in mind. First, to determine whether the amounts of metals present represent any hazard to humans when the fish are used as food. Second, to assess the degree of change in the concentrations over time when compared with a previous study. Third, to discover whether the geographical patterns of metal concentrations point to source areas of elevated stream contamination.
Fish were collected from three stations. Liver and fillet samples were prepared using wet digestion techniques and analyzed using an atomic absorption spectrophotometer. Average concentration in the edible fillet of all fish sampled for all metals studied were below published action levels. Eleven out of sixty-four bass had levels of lead in the fillet above a US FDA action level of 0.25 µg/g. Zinc and copper in bass livers, and zinc in carp livers were significantly higher than in fish sampled in the earlier study. However these increases could be caused by seasonal variations, and not be indicative of a long-term increase in metals levels. Bass from the arm of the reservoir that passes through the most highly developed area of the watershed were found to have significantly higher liver copper levels and fillet mercury levels, than did bass taken from the other stations.Master of Science
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McCluskey, Seánín Marie. "The effect of heavy metals on antibiotic resistance in the environment". Thesis, University of Strathclyde, 2014. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=24354.
Testo completoAbstract (sommario):
Antibiotic resistance is a significant clinical problem, with bacterial infections becoming increasingly difficult to treat. Efforts, such as reducing the use of antibiotics, have proved unsuccessful, and we now face the prospect of a future without antibiotics. The natural environment acts as a reservoir for resistance genes. The selection and maintenance of resistance could counteract clinical efforts to reduce antibiotic resistance. Heavy metals have been linked to antibiotic resistance by genetic mechanisms whereby metals potentially select for and maintain antibiotic resistance, even in the absence of the antibiotic itself. Here, the role of heavy metals in enhancing, or maintaining, antibiotic resistance in the environment is investigated. Background levels of metals in soil were found to correlate to antibiotic resistance gene abundances, implying the effect heavy metals in the environment have on antibiotic resistance is more intrinsic than anticipated. Using controlled microcosm studies, the influence of pollution levels on antibiotic resistance was further investigated.
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Lawton, Michelle. "The effect of heavy metals on differentiated neuronal and glial cells". Thesis, Nottingham Trent University, 2007. http://irep.ntu.ac.uk/id/eprint/219/.
Testo completoAbstract (sommario):
Heavy metal poisoning poses a serious health risk among populations worldwide. The symptoms presented by exposure are varied and depend upon the species of the metal, the age of the individual and the exposure dose. All heavy metals have debilitating effects on the CNS. Children are especially sensitive to the neurological effects due to the intense growth and activity of a developing nervous system and inadequately developed defences. The aims of this study were to determine the effects of sub-lethal concentrations of numerous heavy metals on neuronal and glial cell differentiation. Using established cellular models, the toxicity of zinc, lead, mercury, methylmercury and thimerosal were investigated using assays of cell viability and morphology on differentiating N2a and C6 cells. Initial research revealed thimerosal, methylmercury and cadmium to be the most toxic compounds tested, in terms of their ability to inhibit the outgrowth of neurites in both cell lines at sub-lethal concentrations. Although cadmium chloride showed similar patterns of toxicity to the mercury compounds, thimerosal and MeHgCl were chosen for further investigation at a molecular level. Methylmercury chloride a common environmental pollutant and thimerosal; a preservative found in many medicines, were chosen for further investigation, as previous work has demonstrated the health risks posed by the two organic mercury compounds but little is known about non-lethal changes that occur in the nervous system, especially with thimerosal. Both thimerosal and MeHgCl inhibited MTT reduction and neurite outgrowth after 4 and 24 hours exposure at sub-lethal concentrations (0.1 and 1 µM). The inhibition of neurite outgrowth by sub-lethal concentrations of MeHgCl and thimerosal was accompanied by cytoskeletal changes in the cells. At 4 hours in C6 cells there was no change in the levels of tyrosinated a-tubulin, whereas in N2a cells the level of tubulin tyrosination was shown to be reduced compared to the control. Both cell lines exhibited a fall in total a-tubulin, tyrosinated a-tubulin and total ß-tubulin after 24 hours of exposure to organic mercury compounds, indicating proteolysis and/or reduced synthesis of the tubulin subunit. N2a cells also showed a decrease in the levels of phosphorylation in the neurofilament heavy chain after 4 hours of exposure to thimerosal and MeHgCl, whereas after 24 hours there appeared to be proteolytic degradation, as the total neurofilament heavy chain levels were reduced compared to the untreated controls. Reduced levels of tubulin and NFH were confirmed by immunofluorescence staining of fixed cell monolayers. Western blotting analysis also indicated increased ERK activation in glial cells incubated with 0.1 and 1 µM thimerosal for 4 hours, followed by reduced activation after 24 hours exposure, whereas exposure to MeHgCl decreased the levels of ERK activation at both time points. In the neuronal cell line ERK activation was suppressed at both 4 and 24 hours and with both concentrations of the organic mercury compounds. As ERK activation plays a key role in the regulation of neurite outgrowth and NFH phosphorylation, both of which were inhibited by the addition of thimerosal and MeHgCl, the findings are consistent with a role for disrupted ERK signalling in the sub-lethal toxicity of these compounds. Both thimerosal and MeHgCl caused redistribution of SERCA and ryanodine receptors, both of which are mechanisms by which intracellular Ca2+ concentrations are maintained. As the endoplasmic reticulum (ER) houses both SERCA and ryanodine receptors, the reorganisation may indicate that organic mercury compounds cause redistribution of the ER. Such disruption may lead to sustained increases in intracellular Ca2+, causing elevated activity in Ca2+ dependant enzymes. Indeed, western blotting analysis and enzyme assays showed that calpain activity (particularly calpain 1) increased in response to sub-lethal concentrations of the organic mercury compounds. As calpains target cytoskeletal proteins, the increased activity may be at least partly responsible for reduced levels of tubulin and NFH.
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Kwan, Sai-ping, e 關世平. "Heavy metals in Hong Kong rabbitfish (Siganus canaliculatus)". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31221038.
Testo completo
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Wireko, A. A., Катерина Олексіївна Сікора, Екатерина Алексеевна Сикора, Kateryna Oleksiivna Sikora, Микола Сергійович Линдін, Николай Сергеевич Лындин, Mykola Serhiiovych Lyndin, Наталія Іванівна Гирявенко, Наталья Ивановна Гирявенко e Nataliia Ivanivna Hyriavenko. "Heavy metals effect on the chemical composition variations in rat uterus tissue". Thesis, The Romanian National Library, 2020. https://essuir.sumdu.edu.ua/handle/123456789/81896.
Testo completoAbstract (sommario):
Heavy metals (HM) belong to our vital activity's chemical components, which can be essential, potentially dangerous, and dangerous. Their acceptable concentration present in all layers of the biosphere. Simultaneously, excessive environmental pollution causes the disruption of the living organism’s microecology and imbalanced accumulation of HM in the organs. Besides, it is rather difficult to predict the pollutant effect on the body, as the organs and systems may have different sensitivity. One of these organs that can be exposed to the impact of exogenous factors is the uterus. Moreover, the unknown genesis of HM action on the uterus can lead to severe disorders of reproductive health. The aim of our study was to study the peculiarities of the chemical composition accumulation in the rat`s uterus wall under the experimental HM salts mixture influence.
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Al-Rasheid, Khaled A. S. "The effect of heavy metals on the marine ciliate Euplotes mutabilis (Tuffrau, 1960)". Thesis, University of Southampton, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358875.
Testo completo
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Sikora, Kateryna Oleksiivna, Світлана Григорівна Золотова, Светлана Григорьевна Золотова, Svitlana Hryhorivna Zolotova, Катерина Олексіївна Сікора e Екатерина Алексеевна Сикора. "Dangerous of heavy metals spreading in the environment and their effect on uterus". Thesis, Sumy State University, 2020. https://essuir.sumdu.edu.ua/handle/123456789/77982.
Testo completoAbstract (sommario):
One of the problems of our century is the unfavorable environmental status. Among the large spectrum of pollutants, special attention is paid to the effect of heavy metal salts pollution. These chemical elements in background concentrations can be found in all layers of the ecosystem. Moreover, most of these microelements are essential for the functioning of the organisms. However, when heavy metals enter the body in high concentrations, they may obtain their toxic properties.
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Tomazelli, Andréa Cristina. ""Estudo comparativo das concentrações de cádmio, chumbo e mercúrio em seis bacias hidrográficas do Estado de São Paulo"". Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/59/59139/tde-15032005-173014/.
Testo completoAbstract (sommario):
Concentrações de cádmio (Cd), chumbo (Pb) e mercúrio (Hg) foram determinadas em amostras de água (teores dissolvidos e particulados), sedimento de fundo, peixes e bivalves, coletados em seis bacias hidrográficas do Estado de São Paulo: Alto Paranapanema, Peixe, Aguapeí, São José dos Dourados, Mogi-Guaçu e Piracicaba, as quais apresentam diferentes características quanto ao uso e ocupação da terra. Dentre estas bacias, as dos rios Piracicaba e Mogi-Guaçu apresentam maiores densidades demográficas e industrialização, o que gera, conseqüentemente, maior degradação da qualidade das águas, enfatizando a necessidade de estudos freqüentes nesses sistemas. As amostragens de água e sedimento foram feitas bimestralmente durante o ano de 2001. Os peixes e bivalves foram amostrados no mesmo ano em dois períodos: seca e cheia. As concentrações de Cd e Pb foram determinadas por espectrometria de absorção atômica com atomização eletrotérmica, e as de Hg por espectrometria de fluorescência atômica. Os teores de Cd e Pb na fração trocável do sedimento também foram determinados. Os resultados obtidos mostraram baixas concentrações dos metais Cd e Pb na coluna dágua, tanto nas formas dissolvidas quanto particuladas, no entanto, tais concentrações foram maiores nas bacias dos rios Piracicaba e Mogi-Guaçu. No sedimento de fundo e nos bivalves, as maiores concentrações de Pb foram observadas no rio Mogi-Guaçu, embora este elemento tenha ocorrido em pequenas quantidades na fração trocável do sedimento (<1%). O Cd ocorreu em maiores teores no sedimento e no material particulado do rio Piracicaba. Por outro lado, as maiores concentrações de Pb nos bivalves foram detectadas no rio Mogi-Guaçu. Na fração trocável do sedimento, o Cd ocorreu em altas proporções (até 76%), principalmente, nos rios Itapetininga (Bacia do Alto Paranapanema), Piracicaba e Mogi-Guaçu. Em algumas amostras de água e sedimento de fundo ocorreram quantidades relativamente elevadas de Hg. Por outro lado, nos bivalves os teores do elemento foram sempre baixos. No entanto, nenhuma tendência significativa de distribuição espacial ou temporal de Hg ocorreu nas amostras. Portanto, acredita-se que os altos teores registrados para algumas amostras foram resultantes de fontes de origem difusa não-pontual, como deposição atmosférica e fontes originárias da agricultura. Nos peixes, as concentrações de Cd e Pb foram sempre inferiores aos limites de detecção (0,005 e 0,08 µg/g peso seco, respectivamente). Por outro lado, peixes carnívoros coletados no reservatório de Jurumirim (bacia do Alto Paranapanema) apresentaram altas concentrações de Hg (média: 1,14 +/- 0,54 µg/g peso úmido) e metilmercúrio (média: 1,04 +/- 0,51 µg/g peso úmido). Este último, representou em média 92% do mercúrio total determinado no músculo dos peixes. Tais concentrações foram maiores que o máximo permitido pela legislação brasileira para peixes predadores (1 µg/g peso úmido) e, provavelmente, foram resultante de altos teores de metilmercúrio produzido no reservatório devido aos processos de produção e liberação de mercúrio a partir da vegetação e solos inundados. Portanto, concluiu-se que os peixes do reservatório de Jurumirim estavam contaminados com Hg, recomendando-se que novos estudos sejam realizados para se identificar as fontes e processos responsáveis por tais contaminações. As bacias dos rios do Peixe, Aguapeí, Alto Paranapanema e São José dos Dourados apresentaram baixas quantidades de todos os elementos estudados. Por outro lado, foram observadas concentrações relativamente elevadas de Cd no rio Piracicaba, e Pb e Cd no rio Mogi-Guaçu, os quais devem ser periodicamente avaliados.Concentrations of cadmium (Cd), lead (Pb), and mercury (Hg) were determined in water (dissolved and particulate), bottom sediment, fish, and bivalves sampled in six watersheds located in the State of São Paulo (Southeast, Brazil): the Alto Paranapanema, the Peixe, the Aguapeí, the São José dos Dourados, the Mogi-Guaçu, and the Piracicaba. These watersheds show different levels of land-use. Among these basins, the Piracicaba and the Mogi-Guaçu River Basins show highest population and industrialization rates. Such features lead, consequently, to a higher degradation of water, thus decreasing its quality. These facts emphasize the need of new and frequent studies in those systems. Water and sediment samplings were carried out bimonthly during 2001. Fish and bivalves samples were collected twice a year: at the end of the rainy and dry season. Cd and Pb concentrations were determined through electrotermal atomic absorption spectrometry, whereas Hg through atomic fluorescence spectrometry. In addition, exchangeable Cd and Pb were determined in sediment. The results showed low concentrations of Cd and Pb in water (dissolved and particulate). However, these concentrations were higher in the Piracicaba and the Mogi-Guaçu River Basins. Pb concentrations in sediment and bivalves were the highest in the Mogi-Guaçu River, even so this element occurred in low levels in the exchangeable fraction of sediment (< 1%). The highest Cd concentrations in sediment and particulate suspended matter were related to the Piracicaba River, although the highest levels for bivalves occurred in the Mogi-Guaçu River. High Cd concentrations in the exchangeable fraction of sediment (up to 76%) were observed, mainly in the Itapetininga (the Alto Paranapanema Basin), the Piracicaba, and the Mogi-Guaçu River. High concentrations of Hg were detected in some water and sediment samples, whereas in bivalves Hg was always in low levels. However, no significant tendency of temporal and/or spatial distribution was observed for Hg, so it is belived that the high levels reported for some samples were a result from diffuse non-point source pollution, such as atmospheric deposition and residues from agricultural practices. Cd and Pb concentrations in fish were always lower than the detection limit (0.005 and 0.08 µg/g dry wt, respectively). On the other hand, high concentrations of Hg (1.14 +/- 0,54 µg/g wet wt) and methylmercury (1.04 +/- 0.51 µg/g wet wt), which represented 92% of the total mercury, were found in carnivorous fish samples from the Jurumirim Reservoir (the Alto Paranapanema Basin). These concentrations were higher than the maximum limit permitted by Brazillian legislation for predatory fish (1 µg/g wet wt) and, probably, were a result from high methylmercury levels produced and released in the reservoir supported by inundated soil and vegetation. Hence, we concluded that carnivorous fish from the Jurumirim Reservoir were contamined with Hg, therefore new research sould be carried out in that area in order to identify the sources and processes responsible for high levels of mercury. The Peixe, the Aguapeí, the Alto Paranapanema, and the São José dos Dourados River Basins showed relatively low concentrations of all elements studied. Conversely, high Cd concentrations were determined in the Piracicaba River, and Pb and Cd in the Mogi-Guaçu River, pointing out that these areas should be frequently monitored.
26
Сікора, Владислав Володимирович, Владислав Владимирович Сикора, Vladyslav Volodymyrovych Sikora, Микола Сергійович Линдін, Николай Сергеевич Лындин, Mykola Serhiiovych Lyndin, Наталія Іванівна Гирявенко et al. "Effect of heavy metals on microstructural and microelemental changes in the rats urinary bladder". Thesis, Springer, 2020. https://essuir.sumdu.edu.ua/handle/123456789/81348.
Testo completoAbstract (sommario):
Global environmental pollution leads to the distribution of heavy metal salts (HMS) in the ecosystem and their impact on the organism. To study the influence of the heavy metals (HM) accumulation on the ultrastructural changes in rat’s urinary bladder (UB).
27
Линдін, Микола Сергійович, Николай Сергеевич Лындин, Mykola Serhiiovych Lyndin, Анатолій Миколайович Романюк, Анатолий Николаевич Романюк, Anatolii Mykolaiovych Romaniuk, Роман Андрійович Москаленко, Роман Андреевич Москаленко e Roman Andriiovych Moskalenko. "The effect of heavy metals accumulation on morphological and immunohistochemical features of breast cancer". Thesis, Springer, 2016. http://essuir.sumdu.edu.ua/handle/123456789/46490.
Testo completoAbstract (sommario):
Objective: The chemical composition determination of neoplastic breast :issue,
study of prognostic-important receptors expression in the breast cancer cells,
establishing linkages between all the derived indicators.
28
Lan, Xiao Yu. "Rapid immunological detection of heavy metal cadmium in traditional Chinese medicine". Thesis, University of Macau, 2018. http://umaclib3.umac.mo/record=b3952139.
Testo completo
29
Stanley, Jean Frances. "Studies on the metal-containing granules in the mussels, Mytilus galloprovincialis and Velesunio angasi". Access via Murdoch Univeristy Digital Theses Project, 2003. http://wwwlib.murdoch.edu.au/adt/browse/view/adt-MU20040528.12421.
Testo completo
30
Chen, Xuehui. "Accumulation of heavy metals and organochlorine pesticides in human milk and adipose tissues, and its health concerns". HKBU Institutional Repository, 2007. http://repository.hkbu.edu.hk/etd_ra/779.
Testo completo
31
Ball, Jihane Sokhn. "The effect of heavy metals on the degradation of polycyclic aromatic hydrocarbons by soil microorganisms". Thesis, University of Surrey, 2005. http://epubs.surrey.ac.uk/842888/.
Testo completoAbstract (sommario):
This study aimed to assess the effect of heavy metals, especially Cu, Zn and Cd, on the ability of the white rot fungus (WRF) Bjerkandera sp. BOS55 and several soil bacterial isolates to degrade a selection of polycyclic aromatic hydrocarbons (PAHs). To investigate the effect of heavy metals on PAH degradation by Bjerkandera sp. BOS55, the fungus was grown in both a rich undefined medium and a defined medium containing the PAH pyrene and different concentrations of Cu or Cd. It was found that both metals reduced fungal growth and production of ligninolytic enzymes but that toxicity was modified by the growth medium. The fungus exhibited adaptation and tolerance to both metals in the defined medium containing up to 600 ppm metal but was inhibited in the rich medium containing as little as 50 ppm metal. Whilst WRF are capable of PAH oxidation, complete mineralisation to CO2 is often unachieved resulting in the production of polar and often toxic metabolites. In soil, these metabolites can be further oxidised by bacterial populations to non-toxic products. However, bacteria often exhibit a greater sensitivity to heavy metals than WRF. This sensitivity to heavy metals could block the detoxification process of the soil environment. The three PAH-oxidising bacterial isolates that were tested for metal tolerance were found to be highly susceptible to Cu, Zn and Cd at concentrations of 200 ppm each, resulting in a reduced degradation of phenanthrene and pyrene. It was therefore concluded that the presence of heavy metals in the environment, even at fairly low levels, could potentially lead to the incomplete degradation of PAHs, and possible accumulation of toxic metabolites. Finally, co-cultures of the metal-sensitive bacterial isolates and the fungus were used to establish if a combination of WRF and a bacterial isolate could be used to accelerate the degradation of PAHs. Anthracene and anthraquinone were used as model PAHs because anthraquinone is a dead-end metabolite produced during the oxidation of anthracene by Bjerkandera sp. BOS55. It was found that some of the fungal-bacterial co-cultures tested synergistically removed anthracene, resulting in significantly faster degradation than observed for each organism individually. Moreover, one co-culture removed anthraquinone, suggesting that a combination of WRF and bacteria are essential for the rapid mineralisation of PAHs in the environment.
32
Ghaderian, Seyed Majid. "The effect of toxic heavy metals upon fungi of the genus Pythium isolated from soil". Thesis, University of Sheffield, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301558.
Testo completo
33
Линдіна, Юлія Миколаївна, Юлия Николаевна Лындина, Yuliia Mykolaivna Lyndina, Владислав Володимирович Сікора, Владислав Владимирович Сикора, Vladyslav Volodymyrovych Sikora, Микола Сергійович Линдін et al. "The study of the toxic effect of the heavy metals salts on the erythropoiesis in the rats". Thesis, Springer, 2020. https://essuir.sumdu.edu.ua/handle/123456789/81318.
Testo completoAbstract (sommario):
Heavy metals salts (HMS) are the most common pollutants that are proved to have the negative effect. The objective is to determine the morphological features of the marrow in rats, caused by the combined effect of the heavy metals salts.
34
Maleri, Rudolf A. "The ability of terrestrial Oligochaeta to survive in ultramafic soils and the assessment of toxicity at different levels of organisation". Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/1200.
Testo completoAbstract (sommario):
Thesis (PhD (Botany and Zoology)) -- University of Stellenbosch, 2006.Metals are natural elements of the earth crust usually present at low concentrations in all soils. Although many metals such as cobalt, copper, iron and zinc are essential to living organisms, at elevated concentrations most metals are toxic to organisms living in and on soils. Elevated concentrations of metals are caused either by anthropogenic deposition following remobilisation from the earth crust or are of natural origin. Ultramafic soils do not only pose unfavourable living conditions such as drought and poor organic content, these soils are also characterized by extremely high concentrations of a range of metals known to be toxic under normal circumstances. Ultramafic soils are of high ecological importance as a high proportion of endemic organisms, especially plants, live on these soils. As it is known that earthworms do occur in ultramafic soils, the aims of the present study were to investigate the abilities of earthworms to survive in these soils and the influences of elevated chromium, cobalt, copper, manganese and nickel levels. For the evaluation of the metal background conditions, soils originating from ultramafic rocks of the Barberton Greenstone Belt, Mpumalanga, South Africa were collected and different fractions representing different levels of bioavailability were analyzed for arsenic, chromium, cobalt, copper, manganese and nickel. To assess the mobile, readily available metal fraction, i.e. Ca2+- exchangeable metal cations, a 0.01 mol/L CaCl2 extraction was performed. To investigate the mobilisable metal fraction, representing the amount of easily remobilisable complexed and carbonated metal ions, a DTPA (di-ethylene-triamine-pentaacetic acid) extraction was conducted. In relation to non-ultramafic or anthropogenic contaminated soils, a far lower proportion of metals were extractable by the above mentioned extraction methods. To investigate the availability and effects of these metals on earthworms, two ecophysiologically different species were employed. Aporrectodea caliginosa and Eisenia fetida were long-term exposed to the ultramafic soils collected at the Barberton region and a control soil from a location at Stellenbosch with a known history of no anthropogenic metal contamination. The responses to the ecological stress originating in the ultramafic soils were measured on different levels of earthworm organisation. As endpoints affecting population development, cocoon production, fecundity and viability were evaluated. On individual level, growth, metal body burden and tissue distribution were investigated. As endpoints on subcellular level, the membrane integrity was assessed by the neutral red retention assay, the mitochondrial activity was measured by the MTT colorimetric assay and as a biomarker for the DNA integrity, the comet assay was performed. Focussing on manganese and nickel, the uptake by E. fetida of these metals was investigated with the exclusion of soil related properties using an artificial aqueous medium to draw comparisons to the uptake of these metals in natural soils. The possible development of resistance towards nickel was tested by exposing pre-exposed (for more than 10 generations) E. fetida specimens to ultramafic soils with concentrations of more than 4000 mg/kg nickel. The results showed that, except on the endpoint survival, which was less sensitive than all other bioassays, significant responses to the ultramafic challenge were observed in all earthworm bioassays and on all levels of organisation. The sensitivity of the responses of the earthworms towards the ultramafic conditions was not predictable by the level of organisation. The two species showed different strategies of metal elimination. In A. caliginosa, metals such as nickel, manganese and chromium were transported to the posterior section and the posterior section was subsequently pushed off by autotomization. In E. fetida, metals such as chromium and nickel were sequestered in storage compartments in the coelomic cells or fluid. Other metals, such as cobalt, were not taken up at elevated concentrations. Although an increased accumulation of nickel was observed in E. fetida specimens pre-exposed to nickel, development of resistance or cross resistance was not observed in this species. In contrast, pre-exposed specimen exposed to elevated concentrations of nickel showed a higher sensitivity in terms of survival, indicating the absence of acclimatisation or even genetic adaptation. A comparison of the two species employed indicated that A. caliginosa was less suited for the assessment of the ultramafic soils due to the high individual variation in metal body burden, the mass loss observed and the slow reproduction rate even in the control soils. This happened despite the fact that A. caliginosa was a soil dwelling species supposed to be better adapted to the soil substrate than the litter dwelling E. fetida. The toxicity of the ultramafic soils was not necessarily related to total or environmentally available amounts of the selected metals. Thus, it can be speculated that either these soils contained unidentified toxicants with resulting interactions between toxicants playing an important role or earthworms were able to remobilize metals occurring in these soils. As the singular application of an ecotoxicological endpoint did not give reliable results, especially seen over the duration of the exposures, it can be concluded that, when studying soils with such a complex composition, the utilisation of endpoints addressing different levels of organisation is necessary for the assessment of toxic stress emerging from these ultramafic soils.
35
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.
Testo completoAbstract (sommario):
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.
36
Yuncu, Bilgen. "Effect Of Extracellular Polymer Composition Of Activated Sludge On The Removal Of Heavy Metals By Biosorption". Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1087733/index.pdf.
Testo completoAbstract (sommario):
Activated sludge microorganisms can remove many hazardous substances from
wastewater by adsorbing and concentrating them on their surfaces. Biosorption of
these substances onto activated sludge surfaces are influenced by the chemical
properties of the substance in question as well as the surface properties of the
microorganisms. The purpose of this study is to identify the biosorption
mechanisms of heavy metals and the effect of extracellular polymer (ECP)
composition of activated sludge on the biosorption of Pb(II), Cd(II), Cu(II), Zn(II)
and Ni(II). Microorganisms cultured under different growth conditions are expected
to have different compositions of ECPs and hence, different biosorption capacities.
For this purpose, three sets of reactors with C/N ratios of 9, representing a carbonlimited
case21, representing conventional municipal wastewater treatment plant activated sludge and 43, representing nitrogen-limited condition, were set up. The semi continuous reactors were fed synthetically and operated at a sludge age of 8 days. Isotherm and kinetic experiments that were held with three different C/N ratios was indicated that the biosorptive capacity of activated sludge was highly dependent on metal species and the C/N ratio. Although, the dependence of biosorptive capacity on C/N ratio was different for each metal, biosorption properties of activated sludge were found to be directly related with ECP composition. Among the heavy metals tested, Pb(II) was the one that was adsorbed at the highest capacity at all C/N ratios. Also, with the purpose of understanding the mechanism of the process, Ca(II) and Mg(II) ions and carbohydrates released into the solution were also monitored and it was indicated that an ion exchange process is involved in the biosorption of heavy metals especially at high metal concentrations but the whole metal removal can not be explained by ion exchange.
37
Peppler, Jessica Elise. "The Effect of Heavy Metals on the Uptake of L-Histidine by the Polychaete Nereis Succinea". Thesis, University of Hawaii at Manoa, 2002. http://hdl.handle.net/10125/6957.
Testo completoAbstract (sommario):
Integumentary uptake of 3H-L-Histidine by Nereis succinea was measured in the presence and absence of selected heavy metals and inhibitors in 60% artificial seawater (ASW). At low concentrations of L-Histidine (10 uM), metals stimulated L-Histidine uptake from ASW. Higher concentrations of metal inhibited L-Histidine uptake. In amino acid kinetic experiments, 0.5 uM Zn2+ significantly (P < 0.003) increased both L-Histidine influx Jmax (control: 4.7 ± 0.4; treatment: 15.3 ± 1.7 nmol/g dry weight x 15 min), and Km (control: 23.8 ± 5.1; treatment: 44.0 ± 8.8 uM). Fe3+ (0.5 uM) stimulated influx of 10 uM L-Histidine (Jmax = 6.9 ± 0.4 nmol/g dry wt x 15 min; Km = 86.7 ± 12.3 uM), but neither Ag+ nor Al3+ significantly (P > 0.05) altered amino acid influx. L-Leucine (25 uM) reduced Zn2+ -stimulated L-Histidine influx, suggesting a possible role of the Na-independent L-transport system in metal-stimulated L-Histidine transport by worm integument.vii, 35 leaves
38
Edwards, Paula Kay. "The Correlation of the Concentration of Selected Metals Determined in Water and Fish Samples from a Public Pond". Digital Commons @ East Tennessee State University, 2010. https://dc.etsu.edu/etd/1774.
Testo completoAbstract (sommario):
The concentrations of heavy metals (Cd, Cu, Fe, Ni, Pb, Zn) were measured in water, and fish samples caught from the pond at Fishery Park in Unicoi County, TN. The water samples were collected once a week for 8 weeks. The amounts of metals in the muscle tissues, gill, and liver of the two fish species were measured. This was to determine if any correlation exists between the metal contents in water and those in the fish samples. The concentration ranges for the heavy metals found in the water samples are as follows: Zn 0.04-0.13; Cu, 0.00-0.00; Pb, 0.00-0.59; Cd, 0.0067-0.0071; Fe, 0.208-0.512; and Ni, 0.044-0.270 ppm. The concentration range for the heavy metals found in the fish tissues are as follows: Zn 0.0-0.48; Cu, 0.00-0.00; Pb, 0.00-0.43; Cd, 0.00-99.7; Fe, 25.7-1245.5; and Ni, 0.00-268.5 ppm. There was a strong correlation found between the water and fish tissue samples.
39
Chiu, Ki Kin. "Using organic amendments and chelates for remediation of metal-contaminated soils by vetiveria zizanioides". HKBU Institutional Repository, 2003. http://repository.hkbu.edu.hk/etd_ra/417.
Testo completo
40
Ho, Ching-yee Christina. "The biomonitoring of heavy metal pollution in the wood and leaf chemistry of urban trees in Hong Kong". Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21089978.
Testo completo
41
Ntuli, Themba Dominic. "Preparation of chemically modified Macadamia nutshells for adsorptive removal of selected heavy metals". Thesis, Vaal University of Technology, 2017. http://hdl.handle.net/10352/379.
Testo completoAbstract (sommario):
M. Tech. (Chemistry, Faculty of Applied and Computer Science), Vaal University of TechnologyThe abundance of agricultural waste materials has led to its use as adsorbents for trace metal adsorption. The raw Macadamia nutshell (RMN) powder was treated with a hydrochloric acid solution to obtain acid modified Macadamia nutshells (AMM), and with sodium hydroxide solution to obtain base modified Macadamia nutshells (BMM). Then, the AMM and BMM materials were grafted with 0.5 M, 1 M, and 2 M acrylic acid. The different AMM grafted materials were labelled 0.5 GAM, 1 GAM and 2 GAM representing the different grafting ratios. The same naming order was followed for the BMM grafted materials, that is, 0.5 GBM, 1 GBM and 2 GBM corresponding to different concentrations used. The prepared Macadamia based adsorbents were characterized using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), carbon, hydrogen, nitrogen and sulphur (CHNS) analysis, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) analysis. The determination of surface properties such as the point of zero charge (pHPZC), bulk density and the surface negative charge was accomplished with appropriate wet chemistry methods. The adsorption of selected trace metals (Cu(II), Cd(II), Co(II), and Cr(VI)) was done in batch experiments. Atomic absorption spectroscopy (AAS) was used for the determination of metal ions concentrations and total Cr. The ultraviolet-visible (UV–Vis) spectroscopy was used for the determination of Cr(VI) concentration remaining in solution after adsorption. The RMN, AMM, and BMM adsorbents showed potential in removing more than 45% Cu(II) ions, but less than 30% for both Cd(II) and Co(II) ions. However, more than 90% removal of Cr(VI) ions was achieved with the same adsorbents. Consequently, only the adsorption of Cr(VI) was further investigated in the study due to the higher removal efficiency displayed by the Macadamia based biosorbents. The optimum adsorption conditions for the RMN, AMM, and BMM materials were found to be pH 2, 100 mg/L initial concentration of Cr(VI), 600 min contact time and 0.2 g adsorbent mass. The ideal conditions for the 0.5 GAM and 0.5 GBM were found to be pH 2, 25 mg/L initial concentration of Cr(VI), 180 min contact time, and 0.15 g adsorbent mass. The optimum temperature was found to be 40℃ for all materials. A volume of 20 mL was used for all batch experiments. The RMN, AMM, BMM, 0.5 GBM, and 0.5 GAM adsorption mechanisms were better described by the Langmuir isotherm which predicted a monolayer sorption process. The kinetic data fitted better to the pseudo second-order rate model which signified a chemisorption type of interaction. The thermodynamic parameters showed that the adsorption reaction was feasible, spontaneous and endothermic. The Macadamia based materials showed greater potential as adsorbents for the adsorption of Cr(VI) ions from aqueous solution compared to the other selected trace metal ions [Cd(II), Cu(II) and Co(II)].
42
Hong, Wei. "Investigation on heavy metals and species of arsenic in natural Cordyceps sinensis". Thesis, University of Macau, 2008. http://umaclib3.umac.mo/record=b2162715.
Testo completo
43
Clements, William H. "Community responses of aquatic macroinvertebrates to heavy metals in laboratory and outdoor experimental streams". Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/53937.
Testo completoAbstract (sommario):
This research describes aquatic macroinvertebrate community responses to heavy metals (copper, zinc) in experimental streams and at metal-impacted sites in the field. Experiments employed substrate-filled trays which were colonized in the field and then transferred to laboratory or outdoor streams.
Laboratory experiments conducted over three seasons showed that acute (96 h) exposure to copper (Cu) at 15-32 μg Cu/L significantly reduced macroinvertebrate abundance and number of taxa during each season. Owing to differences in sensitivity among taxa, the percent composition of dominant groups varied between control and dosed streams. Mayflies were quite sensitive to Cu, particularly during the summer when water temperatures were higher.
Community responses to Cu and Zn in outdoor experimental streams were similar to those observed at metal-impacted sites in the field. Control streams and field reference Stations were dominated by mayflies and Tanytarsini chironomids. In contrast, treated Streams and impacted field sites were dominated by net-Spinning caddisflies (Hydropsychidae) and Orthocladiini chironomids. The similarity of these experimental results to those observed in the field suggest that macroinvertebrate community responses to heavy metals are highly predictable.
Responses of these communities to Cu were greatly influenced by water quality. Effects were more severe in New River Streams, where water hardness and alkalinity were low, compared to Clinch River Streams, where hardness and alkalinity were higher. In soft water Streams, abundance was reduced by 84% after 10 d exposure to Cu (measured concentration = 13 μg/L). In contrast, abundance was reduced by only 45% in hard water Streams after 10 d at Similar Cu levels. These results demonstrate the importance of accounting for water quality characteristics of receiving systems when establishing site-specific criteria for metals.
Chronic exposure (14 d) to sublethal levels of Cu (< 6 μg/L) increased Vulnerability of caddisflies (Hydropsyche morosa and Chimarra sp.) to predation by the Stonefly, Paragnetina fumosa. Caddisflies were also the major component of stonefly diets and were consumed Significantly more frequently in dosed Streams than controls. These results demonstrate that single Species bioassays were inadequate for predicting effects of toxicants on community level processes.Ph. D.
44
Diouf, Aissatou. "Effect of Organic Amendments on Heavy Metal Distribution and Uptake in Vegetable Gardens in Senegal". Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/73036.
Testo completoAbstract (sommario):
The major constraints to food production in West Africa are related to the lack of suitable lands. Consequently, farmers incorporate organic amendments and wastewater to improve their yields. Within some limits, such wastes enhance soil fertility and can improve its physical properties. However, the advantages of using organic waste as fertilizer and soil amendment should be assessed with possible environmental and toxicological impacts due to the potential presence of heavy metals. The objective of this study was to assess the effect of organic amendments on heavy metal distribution in soils and vegetables in market gardens in Senegal. Organic amendments and soils samples were collected from four sites in eastern and southern Senegal. Samples were analyzed for physicochemical properties including particle size, total heavy metals, carbon content, nutrients, and pH. A sequential extraction procedure was conducted to determine heavy metal sinks. Results showed that sites were sandy in nature, low to medium in organic carbon content (8300 to 36600 mg kg-1), and had pH ranging from 5 to 7.9. The sequential extraction procedure showed that metals were distributed in the more stable soil fractions: Fe-Mn oxide, organic and residual. The highest soil metal concentrations in soils were found in Pikine and Rufisque sites. Plant samples were collected from these two sites and analyzed for total metal content. Results showed that all metal concentrations in soils, organic amendments, and vegetables were within the safe limits proposed by the World Health Organization, with the exception of Cd, Pb and Zn levels in vegetables.Master of Science
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Peterson, Robert. "Interaction Effect of Filler Material on Fungal Biomass Activity for Heavy Metal Biosorption in Stormwater". Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-14984.
Testo completoAbstract (sommario):
In the wake of ever more occurring and evident consequences brought by climate change such as droughts and an increasing world population, a responsible use and handling of freshwater has never been as important as before. Stormwater is more than often not treated and simply released back in nature with any kind of pollution it has collected on its way, one of which being heavy metals. By treating stormwater not only would this underutilised resource be made use of, creating a new source of freshwater, but environmental pollution caused by untreated stormwater could be potentially decreased, as it can be converted into a potential resource rather than a waste caused by nature. There are a number of already established methods to lower the concentration of heavy metals in water, however there are inherent economical and practical disadvantages with each of them. A method that has shown promising results with potential to challenge these contemporary solutions is biosorption. This study has explored the use of fungal biomass of Rhizopus oryzae for heavy metal biosorption in conjuncture with an organic filler material. The metals investigated were Zn, Cu and Fe. Moreover, the effects of pre-treating the fungal biomass with primarily NaOH were also investigated together with the optimal ratio between biomass and filler material and retention time, in order to maximise biosorption.Pre-treating the fungal biomass with NaOH resulted in a considerable increase in biosorption. Moreover, the presence of the filler material had a positive impact on biosorption by further enhancing it. The best effect was obtained at a 4:1 ratio between biomass and filler material. Finally, the best retention time was determined to be around 2 hours, slowly levelling off at higher retention times. However, the use of pre-treated R. oryzae with filler material did not prove to be efficient regarding the removal of heavy metal ions in stormwater at very low concentration of metals, between approximately 4 to 10 ppb. In the future, it would be worthwhile to investigate the viability of this method on stormwater with higher metal concentrations as well as looking into the effects of pH and temperature.Som en påföljd av de konsekvenser som klimatförändringen har orsakat, som till exempel svåra torkor tillsammans med en ökande världsbefolkning, har det blivit av allt större vikt att hanteringen av sötvatten sker på ett mer ansvarsfullt och hållbart sätt. Stormvatten brukar inte behandlas överhuvudtaget utan släpps tillbaka i miljön tillsammans med föroreningarna som det samlat på sig under sin väg, bland annat tungmetaller.Det finns redan ett antal metoder för att minska koncentrationen av tungmetaller i vatten, dock inte utan ekonomiska och praktiska svårigheter. Hur som helst så har det forskats en del kring en relativt ny metod som har tidigare visat goda resultat och skulle kunna konkurrera med befintliga lösningar, nämligen biosorption. I denna studie har man utforskat möjligheten att använda svampen Rhizopus oryzae tillsammans med ett organiskt fyllmedelsmaterial för biosorptionen av tungmetaller i stormvatten. De tungmetaller som undersöktes var Zn, Cu och Fe. Dessutom har man undersökt effekterna av ett förbehandlingssteg hos biomassan med NaOH tillsammans med det optimala förhållandet mellan biomassan och fyllemedelsmaterialet och retentionstiden för att maximera biosorptionen. Förbehandlingssteget visade en markant förbättring av biosorptionen. Fyllemedelsmaterialet hade för övrigt också en positiv inverkan genom att ytterligare öka biosorptionen. Ett 4:1 förhållande mellan biomassan och fyllemedelsmaterialet resulterade i det optimala förhållandet för komponenterna med tanke på biosorptionen. För retentionstiden visade det sig de bästa resultaten erhålles vid 2 timmar i lösningen. Emellertid visade det sig att användningen av den förbehandlade svampen tillsammans med fyllemedelsmaterialet inte var effektivt på stormvatten med en väldig låg tungmetallkoncentration, ungefär mellan 4 till 10 ppb. I framtiden skulle det vara intressant att undersöka inte bara metodens genomförbarhet på stormvatten med högre metallkoncentrationer, utan även hur pH-värde samt temperatur kan påverka resultaten.
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Bateman, Mark J. "The uptake of heavy metals by aquatic macrophytes and the development of microsampling analytical techniques". Thesis, Coventry University, 1999. http://curve.coventry.ac.uk/open/items/82ba9974-f8fc-6290-40a7-3a64e63ff8a6/1.
Testo completoAbstract (sommario):
This thesis reviews literature relating both to the treatment of metal rich wastewaters by the use of constructed wetlands and the use of slurry analytical procedures for the determination of heavy metals in environmental micro-samples. A survey of metal contaminated wetland sites showed that aquatic plants maintain low levels of metals in aerial parts despite some very elevated sediment metal concentrations and extreme acidity. A series of greenhouse trials investigated the uptake of metals into aerial sections of Typha, Phragmites and Equisetum in long term hydroponic experiments. Phragmites was shown to accumulate zinc to a higher level than Typha. The toxicity of zinc supplied in the nutrient solution at 5 mg.dm-3 over long periods was found to limit the viability of such non-sediment based systems. A reliable routine analytical procedure was developed along with a program of quality control for the study of metal uptake into aquatic plants. A micro sampling technique, eminently suited for the analysis of small plant sections was developed. This technique uses ozone to ash the plant samples at a low temperature and following suspension in a liquid medium provides a sample ready for slurry determinations by a variety of analytical instrumentation. It is proposed that this method may also be suitable for the determination of metals in individual invertebrates and other zoological micro-samples as well as potential applications in the medical field.
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Obbard, Jeffrey Philip. "The effect of heavy metals on microbial processes related to nutrient cycling in sewage sludged-amended soils". Thesis, Lancaster University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306430.
Testo completo
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Hagos, Mebrahtu T. "Effect of heavy metals on spawning and hatching of Penaeus indicus in KwaZulu-Natal (Amatikulu Prawn Farm)". Master's thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/6262.
Testo completoAbstract (sommario):
Includes bibliographical references.Generally aquaculture continues to suffer from pollution and this has resulted in the decline of production. The effect of pollution can be directly on the organisations cultured causing immediate death or retarding their growth and making them vulnerable to a variety of diseases, or indirectly by reducing their reproductive capacity. This study was carried out to investigate the effect of zinc and lead on the hatched eggs, and zinc and copper on spawing and hatching of eggs from mature female Penaeus indicus. The experiment for each heavy metal was conducted separately. In the post-spawning experiment, hatched eggs were counted and exposed to 0.0, 0.1, 10., 10.0 and 100 ppm of zinc and lead to see the effect of the heavy metals on hatching of the eggs and survival of the hatched eggs. Concentrations of 0.0, 0.1 and 1.0 ppm of zinc and lead did not show signicant difference of hatch rate among each other but 10.0 and 100.0 ppm of zinc and lead gave significantly lower hatch rate as compared with the lower concentrations. Hatch rate completely failed at 100.0 ppm of both heavy metals.
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Serot, Julie Lynn. "Heavy metal analysis in Heaviside's dolphins (Cephalorhyncus heavisidii)". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/193469.
Testo completoAbstract (sommario):
Skin and blubber tissue samples were collected from two hundred and six freeranging Heaviside’s dolphins (Cephalorhyncus heavisidii) during January through June of 2008, 2009, and 2010, along the coast of South Western Africa, to be analyzed for heavy metal concentration levels. Inductively coupled mass spectrometry (ICP-MS) was used to determine sample solution concentrations of all metals (aluminum, arsenic, cadmium, chromium, copper, iron, lead, manganese, mercury, nickel, selenium and zinc). Data provided by this thesis is the first reference of its kind for this species (Cephalorhyncus heavisidii), which is one of the least-known cetacean species in the world. In addition to baseline heavy metal concentration information for the Heaviside’s dolphin, meaningful population structural and ecological information was obtained. A level of site fidelity or specific movement pattern across certain sites was indicated by the presence of different concentration levels across individuals sampled in different areas, especially adjacent areas. With an investigation into the potential sources of the marine heavy metal contamination, it was deduced that these sources contributed to each site’s unique and characteristic toxicological and hydrological profile as reflected by the bioaccumulation patterns seen in this study. It was confirmed by this study that bioaccumulation levels are a meaningful and novel measure of population structure. Potential evidence of differences in bioaccumulation patterns between sexes was observed in this study, as well. Although not definitive, a difference in metabolism, heavy metal elimination, or ranging pattern between males and females was suggested by the results. Variation in the results suggests a deepened level of complexity in the physiological and ecological aspects of trace elements accumulation and detoxification in the tissue of an apex predator like the Heaviside’s dolphin. Finally, a general assessment of health implications for the species was established, and it was found that Heaviside’s dolphins have higher than average mammalian trace element concentrations, and higher than average concentrations as specifically compared with other odontocetes. Further research using a larger sample size and using internal organs will provide more insight and a deeper understanding of the novel information presented here.published_or_final_version
Biological Sciences
Master
Master of Philosophy
50
Pheiffer, Wihan. "Investigating morphological changes in fish tissue, due to the presence of persistent organic pollutants and metals / W. Pheiffer". Thesis, North-West University, 2012. http://hdl.handle.net/10394/9814.
Testo completoAbstract (sommario):
Levels of selected metals and persistent organic pollutants (POPs) were investigated in sediment and fillet tissue of the sharptooth catfish (Clarias gariepinus), from sites along the Orange-Vaal River system, South Africa.
A histological assessment was done on the livers, kidneys, and gills of the fish sampled to determine morphological changes. The sediment and fish sampling sites were selected up- and downstream of major pollution sources such as mining, industrial and agriculture. The concentrations of the metals in the fish and sediment was determined with an inductively coupled plasma mass spectrometry and the POPs with a high resolution gas chromatographyhigh resolution mass spectrometer. Indices were calculated to describe the quality of the sediment The enrichment factor (Ef) of individual heavy metals evaluated elevation in levels above natural geology. The geo-accumulation index (Igeo) determined the degree of pollution by the enrichment levels of the individual metals. The pollution effect of the total mixture of the heavy metals was investigated by the metal pollution index (MPI) and pollution load index (PLI). Ecological risk was determined by calculating the sediment quality guideline index (SQG-I) and a sediment quality index (SQI) to determine the quality of the sediment. For the SQG-I and SQI, international sediment quality guidelines were used, since South Africa does not have them. The bio-accumulation factor (BF) was calculated between sediment and fish. A limited human health risk assessment was done for the consumption of Clarias gariepinus. A semi-quantitative histopathological assessment was preformed and alterations found were numerically described with the aid of mean organ indices.
The POPs values were very low. The Igeo and Ef of Se, Hg, Ag and Au were the highest at all the sites. Parys had the most metals that were enriched to different degrees, but Rooipoort had the highest MPI and PLI. The SQG-I indicated that the sites had a moderate chance of posing an ecological risk to its biota, except for Rooipoort that had a high toxic probability. The SQI classified Rooipoort as “fair” in terms of sediment quality and the rest of the sites as “good”. The semi-quantitative histology based assessment results showed that the mean organ and fish indices fell within class 1 (normal tissue structure with slight histological alterations) or class 2 (normal tissue structure with moderate histological alterations). The mean gill, -liver and kidney indices for all the sites fell in class 1. The mean fish index for all the sites however, fell in class 2. The human health risk assesment showed high risk for non-carcinogenic effects from Ag, Hg, As and Cr if fish from the sample sites were to be consumed.
The results from this study identified that the river system is polluted by anthropogenic activities. Results showed that the pollutants of concern in the system were ultimately Ag, Hg and PFOS. Although the morphology of Clarias gariepinus was not altered, the results indicated that the Orange-Vaal River system is polluted and that these fish is unsafe for human consumption.Thesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2013.