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1
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
2
High, Kim. "Metal-specific high-performance liquid chromatography detection approaches for the characterization of metallothionein-like proteins from freshwater mussels". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0012/NQ29958.pdf.
Testo completo
3
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]
4
Davies, Nicola Anne. "Uptake of heavy metals from artificial sediments by Mytilus edulis". Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295239.
Testo completo
5
Freeman, Emily K. "Effects of Dreissenid Mussel Druses on Heavy Metals Transfer via Benthic Macroinvertebrates". Bowling Green State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1372077038.
Testo completo
6
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.
7
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.
8
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.
9
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.)
10
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)
11
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.
12
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.
13
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
14
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
15
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
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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
17
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
18
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.
19
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.
20
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.
21
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.
22
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
23
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
24
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
25
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)].
26
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
27
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.
28
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.
29
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.
30
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.
31
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
32
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.
34
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
35
Butler, Reece. "Effect of Heavy Metals Found in Flue Gas on Growth and Lipid Accumulation for Green Algae Scenedesmus obliquus". DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/1159.
Testo completoAbstract (sommario):
This study evaluated the effect of several heavy metals that are present in flue gases on the algae, focusing on the growth and accumulation of lipids in the algae that can be converted to biodiesel. Concentrations for the heavy metals were calculated based on literature and assumptions. Metals were tested individually first at the highest concentrations that might be present (reference concentrations). The metals and their reference concentrations were: arsenic at 1.56 mg/L, cadmium at 0.3 mg/L, chromium at 2.6 mg/L, cobalt at 0.32 mg/L, copper at 2.62 mg/L, lead at 1.09 mg/L, nickel at 5.08 mg/L, mercury at 0.2 mg/L, selenium at 0.2 mg/L, and zinc at 8.8 mg/L. At these concentrations, most of the metals had a negative effect on the growth and lipid content of the algae. All of the metals were then tested at lower concentrations. At 1/20 the reference concentrations, the metals enhanced growth as well as lipid accumulation in the algae. At higher concentrations there was a negative effect.
36
Cornelissen, Stephanie. "The impact of copper on filamentous fungi and yeasts present in soil". Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/16290.
Testo completoAbstract (sommario):
Thesis (MSc)--University of Stellenbosch, 2004.ENGLISH ABSTRACT: Numerous workers studied the impact of pollutants and agricultural chemicals, containing heavy metals such as copper (Cu), on soil microbes. It was found that elevated soil Cu levels do have a detrimental effect on soil bacterial populations however the filamentous fungi seemed to be less affected. Most of these studies were conducted in soils containing already relatively high Cu levels and the effect of this heavy metal on the nonfilamentous fungi (i.e. yeasts) was never investigated. The aim of this study was therefore to determine the impact of elevated Cu levels on filamentous fungi and yeasts occurring in soils containing relatively low natural Cu levels. A synthetic selective medium containing glucose as carbon source, thymine as nitrogen source, vitamins, minerals and chloramphenicol as anti-bacterial agent (TMV-agar), was used to enumerate ascomycetous and basidiomycetous Cu resistant yeasts in a sample of virgin soil containing ~ 2ppm Cu. Media that were used to enumerate Cu resistant filamentous fungi were malt extract agar, malt extract agar with streptomycin sulfate, maltyeast- extract-peptone agar with chloramphenicol and streptomycin sulfate, benomyl–dichloran-streptomycin medium for the enumeration of hymenomycetous fungi and two selective media for the isolation of mucoralean fungi. Cu resistant fungi able to grow on all of the above mentioned solid media supplemented with 32 ppm Cu occurred in the soil sample. To obtain an indication of the level of Cu tolerance of fungi present in this soil sample, a number of fungal isolates were screened for the ability to grow on a series of agar plates, prepared from glucose-glutamate-yeast extract agar, containing increasing concentrations of Cu. It was found that filamentous fungi and yeasts that were able to grow on this agar medium containing up to 100 ppm Cu were present in the soil. A series of soil microcosms was subsequently prepared from the soil sample by experimentally contaminating the soil with increasing amounts of copper oxychloride, were after fungal populations in the microcosms, including Cu resistant fungi, were monitored using plate counts. At the end of the incubation period, after 245 days, fungal biomass in the microcosms was compared by determining the concentrations of the fungal sterol, ergosterol, inthe soil. Generally, Cu had little impact on the numbers of filamentous fungal colony forming units on the plates, as well as on the ergosterol content of the soil. The numbers of filamentous fungi in the soil, including the Mucorales and hymenomycetes, seemed to be less affected by the addition of copper oxychloride than the numbers of soil yeasts able to grow on TMV-agar. The focus of the next chapter was on the response of yeasts in different soils to elevated levels of Cu in the soil. TMV-agar was used to enumerate yeasts in soil microcosms prepared from four different soil samples, which were experimentally treated with copper oxychloride resulting in Cu concentrations of up to 1000 ppm. The selective medium supplemented with 32 ppm Cu was used to enumerate Cu resistant yeasts in the microcosms. The results showed that the addition of Cu at concentrations ≥ ~1000 ppm did not have a significant effect on total yeast numbers in the soil. Furthermore, it was found that Cu resistant yeasts were present in all the soil samples regardless of the amount of Cu that the soil was challenged with. At the end of the incubation period, yeasts in the microcosms with zero and ~1000 ppm additional Cu were enumerated, isolated and identified using sequence analyses of the D1/D2 600-650bp region of the large subunit of ribosomal DNA. Hymenomycetous species dominated in the control soil, while higher numbers of the urediniomycetous species were found in the soil that received Cu. These observations suggest that urediniomycetous yeasts may play an important role in re-establishing overall microbial activity in soils following perturbations such as the addition of Cu-based fungicides.
AFRIKAANSE OPSOMMING: Vele navorsers het al die impak van besoedelingstowwe en landbouchemikalieë wat swaarmetale soos koper (Cu) bevat, op grond-mikrobes bestudeer. Dit is gevind dat verhoogde Cu vlakke ‘n nadelige effek het op grond-bakteriese populasies, maar dat die filamentagtige fungi geneig is om minder geaffekteer te word. Meeste van hierdie studies is gedoen met gronde wat alreeds relatief hoë Cu vlakke bevat het en die effek van hierdie swaarmetaal op die nie-filamentagtige fungi (d.i. giste) is nooit ondersoek nie. Die doel van hierdie studie was dus om die impak van verhoogde Cu vlakke op filamentagtige fungi en giste in gronde, wat natuurlike lae vlakke van Cu bevat, te bepaal. ‘n Sintetiese selektiewe medium wat glukose as koolstofbron, timien as stikstofbron, vitamiene, minerale asook chloramfenikol as anti-bakteriese agent bevat (TMV-agar), is gebruik om askomisete en basidiomisete Cu weerstandbiedende giste in ‘n monster ongeskonde grond, bevattende ~ 2dpm Cu, te tel. Media wat gebruik is om Cu weerstandbiedende filamentagtige fungi te tel, was mout-ekstrak agar, moutekstrak agar met streptomisiensulfaat, benomiel-dichloran-streptomisien medium vir die tel van hiemenomiseetagtige fungi en twee media vir die isolasie van mukoraliese fungi. Cu-weerstandbiedende fungi wat op al die bogenoemde media, aangevul met 32 dpm Cu, kon groei, het in die grondmonster voorgekom. Om die mate van Cu-weerstandbiedendheid van fungi wat in die grondmonster voorkom, te bepaal, is ‘n getal fungus-isolate op agarplate, voorberei met glukose-glutamaat-gis ekstrak agar, bevattende verhoogde konsentrasies Cu, nagegaan. Daar is gevind dat daar filamentagtige fungi en giste in die grond voorkom wat die vermoë het om op media bevattende 100 dpm Cu te groei. ‘n Reeks grond mikrokosmosse is dus voorberei vanaf die grondmonster deur om dit eksperimenteel te kontamineer met verhoogde hoeveelhede koper oksichloried, waarna die fungus-populasies asook die Cu-weerstandbiedende fungi in die mikrokosmos gemoniteer is deur middel van plaattellings. Aan die einde van die inkubasie periode, 245 dae, is die fungus biomassa in al die mikrokosmosse bereken deur die konsentrasie van die fungus sterool ergosterool te bepaal en dit met mekaar te vergelyk. Oor die algemeen het Cu min impak ten opsigte van diegetal filamentagtige fungi kolonie vormende eenhede die plate, asook op die ergosterool inhoud van die grond gehad. Dit wil voorkom of die getal filamentagtige fungi in die grond, insluitende die Mucorales en die hymenomisete, minder geaffekteer is deur die toediening van koperoksichloried as die aantal grondgiste wat op die TMV-agar kan groei. Die fokus van die volgende hoofstuk was dus op die reaksie wat giste in verskillende grondtipes gehad het op verhoogde Cu in die grond. TMV-agar is gebruik om die getal giste te bepaal in die grond mikrokosmosse van die vier verskillende grondmonsters, wat voorberei is deur om dit eksperimenteel met koper oksikloried te kontamineer tot en met Cu konsentrasies van 1000 dpm. Die selektiewe medium wat gesupplementeer is met 32 dpm Cu, is gebruik om Cu weerstandbiedende giste in die mikrokosmosse te bepaal. Die resultate toon dat die toevoeging van Cu by konsentrasies ≥ ~1000 dpm nie enige beduidende effek op die totale gis getalle gehad het nie. Daar is ook gevind dat daar Cu weerstandbiedende giste in die grond monsters voorkom gekom het ten spyte van die hoeveelheid Cu wat tot die grond toegevoeg is. Aan die einde van die inkubasie periode is die giste wat die die mikrokosmosse bevattende nul en ~1000 dpm Cu getel, geïsoleer en geïdentifiseer deur gebruik te maak van DNA volgorde bepaling van die D1/D2 600-650 bp areas geleë in die groter subeenheid van die ribosonale DNA. Hymenomisete spesies het in die grond kontrole gedomineer, terwyl hoër getalle uredinomisete spesies in die grond met addisionele Cu gevind is. Die resultate dui daarop dat uredinomisete giste dalk ‘n belangrike rol kan speel in die hervestiging van die oorwegende mikrobiese aktiwiteit in grond na skoktoestande soos die aanwending van Cu-gebaseerde fungisiede.
37
Deng, Hong. "Metal (Pb, Zn, Cu, Cd, Fe) uptake, tolerance and radial oxygen loss in typical wetland plants". HKBU Institutional Repository, 2005. http://repository.hkbu.edu.hk/etd_ra/629.
Testo completo
38
Farris, Jerry L. "Cellulolytic responses to heavy metal accumulation in Corbicula fluminea and Mudalia dilatata". Diss., This resource online, 1986. http://scholar.lib.vt.edu/theses/available/etd-01242009-063436/.
Testo completo
39
Piola, Richard Fabio Biological Earth & Environmental Sciences Faculty of Science UNSW. "Differential tolerance of introduced & native marine invertebrates to heavy metal pollution". Publisher:University of New South Wales. Biological, Earth & Environmental Sciences, 2007. http://handle.unsw.edu.au/1959.4/40673.
Testo completoAbstract (sommario):
In near-shore marine environments, two of the most prevalent anthropogenic disturbances affecting ecosystem diversity and function are the invasion of exotic species, and the release of toxic chemicals. Estuarine and harbour environments worldwide are dually subjected to high levels of toxic disturbance and ever increasing rates of invasion, via activities such as boating and shipping. It is not clear, however, whether the success of invasive species is influenced by the presence of toxic contaminants in these impacted environments. In particular, nonindigenous marine species (NIS) may be advantaged in chemically disturbed environments if they are more tolerant of toxicants. This thesis examines whether nonindigenous and native sessile invertebrate species have differential tolerance to a common aquatic contaminant, copper (Cu), which has links to both the invasion process (via its use in antifouling paints and the vector of hull fouling) and the modification of recipient environments (via human-mediated pollution). A series of laboratory- and field-based experiments showed that the cosmopolitan invasive bryozoans Watersipora subtorquata, Bugula neritina and Schizoporella errata are highly tolerant of copper pollution. The larvae and adults of W. subtorquata and B. neritina in particular were able to survive and grow in copper-polluted environments far exceeding most observed real-world levels (< 100 /??g 1-1). These nonindigenous species also showed very strong postexposure recovery. In contrast, the co-occurring native bryozoans Celleporaria nodulosa and Fenestrulina mutabilis demonstrated comparatively low tolerance to copper, with markedly reduced survival and fitness under Cu contaminated conditions, and inferior recovery abilities post-exposure. These findings were further supported by a long-term manipulative field experiment, examining the effect that varying levels of Cu exposure have on the structure and diversity of developing sessile invertebrate assemblages. Cu exposure decreased native species diversity by up to 50%, yet had no effect on NIS numbers. Consequently, in the presence of copper contamination, NIS dominated sessile communities, often resulting in substantial changes to community structure. Important insights were also gained into the nature of metal tolerance in NIS. Toxicity studies on larvae of the introduced bryozoan Bugula neritina revealed intraspecific differences in tolerance to Cu, associated with the level of pollution experienced by the adult source populations. There was also evidence of fitness costs related with increased Cu tolerance. In summary, we have found evidence that the success of invasive species is influenced by chemical contamination. NIS may be advantaged in contaminated estuaries relative to native species and this may assist in their establishment and persistence in new habitats.
40
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
41
Wu, Yonghong 1969. "Bioavailability and rhizotoxicity of trace metals to pea : development of a terrestrial biotic ligand model". Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103309.
Testo completoAbstract (sommario):
Risk assessment of trace-metal contamination in soils requires predictive models that can accurately describe the complex uptake processes at the soil-plant interface, which are usually characterized by the coexistence of and interaction between multiple components. Competing cations such as Ca and H can affect metal availability to plants and subsequent rhizotoxicity. The biotic ligand model (BLM) has been proposed as a promising approach to model these interactive processes. Under the BLM assumption, we designed experiments to investigate how the solution chemistry is correlated with metal uptake and rhizotoxicity. Our first goal is to acquire a set of BLM parameters that can accurately represent the experimental data over varied solution conditions and parameters that are easy to integrate with general speciation models. The second objective is to get insight into the physical nature of the interactions. Our titration experiments revealed three types of biotic ligands in the pea roots with defined site densities and stability constants with H. Our ion sorption experiments estimated the surface-adsorption stability constants of Ca, Mg, Cd, Cu, Ni, and Zn with excised fresh pea roots. Our 48-h root growth tests have established the formation constants (KMe's) of living pea roots with Ca, Cd, Cu, Ni, and Zn. In these studies, we hypothesized and confirmed that the concentration of the metal-root complexes correlated with observed rhizotoxicity and that Ca, H, and trace metals competed for root absorption where lower solution pH decreased both Ca and metal uptake. Root elongation was found to be highly sensitive to root Ca content rather than merely to the direct toxic effects of the trace metals. It is shown that the physiological complexity arising from a living root affected our modeling so that adjustable KMe values, as a function of solution and root chemistry, are required for good model fits. The established model parameters were tested in hydroponic mixture solutions for their ability to predict the uptake of multiple metals simultaneously. The joint effects of Cd, Cu, and Ni in mixtures on root growth were studied and the potential interactions between these ions were also investigated.
42
Mohammed, Nagib F. J. B. "Effect of heavy metals on the biological activities of marine fishes, with special reference to their reproduction and development". Thesis, Swansea University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638215.
Testo completoAbstract (sommario):
Oogenesis is examined in two rockling species. Seven developmental stages are described in Ciliata mustela L. and six stages in Gairdropsarus mediterraneus L., since both species were collected at the same time, suggesting the possibility of an earlier spawning in the first species. Ultrastructural differences in the zona radiata occur, monopartite in G. mediterraneus and bipartite and double thickness in C. mustela. Cortical alveoli are first formed in the cortex originating from Golgi vesicles. Ultrastructural evidence suggests that protein yolk formation has a contribution from both exogenous and endogenous sources while lipid yolk is solely endogenous. The endogenous protein is synthesised by Golgi complexes. Lipid yolk is formed in close association with rough endoplasmic reticulum in G. mediterraneus and annulate lamellae in C. mustela suggesting that both organelles play a role in lipid formation. Fertilised eggs of Clupea harengus L. were exposed to different acid pHs. Egg, perivitelline space, and yolk volumes were measured in relation to osmoregulation. The effect of acid on the morphology of the hatched larvae was also demonstrated. Jaw, branchial and skeletal abnormalities were observed. Exophthalmus condition was recorded in these larvae. Acid water causes epidermal necrosis, degeneration of the chloride cells, and swelling of the membrane-bound structures of the trunk muscle tissue at the ultrastructural level. The study demonstrates that aluminium is extremely toxic at pH 5.0 causing 99.52% cumulative mortality to C. harengus eggs. Ultrastructural and morphometric evidence show that aluminium causes disruption and swelling in the cell membranes of the brain and muscle tissues of C. harengus larvae accompanied by degeneration of mitochondrial cristae. Such effects would reduce the metabolic activity and survival potential of these larvae with subsequent consequences on recruitment success of the stock.
43
LESSA, MARCUS PAULO FOURNIER. "STUDY OF EFFECT FOR APLICATION TO A HUMIC COMPOUND OF MINERAL SOURCE ON HEAVY METALS PRESENTS IN SEWAGE SLUDGE". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2004. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=5924@1.
Testo completoAbstract (sommario):
CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCom base no procedimento EPA-3050B, estudou-se o teor de metais (Cd, Cr, Cu, Ni, Pb, e Zn) em lodos de esgoto da CETESB. Foram analisadas duas amostras e os resultados obtidos foram (Cd =3,4 ; Cr =367,5 ; Cu =263,0 ; Ni=290,6 ; Pb =91,5 ; Zn =1324,9 mg/ kg) para primeira amostra e (Cd =3,0 ; Cr =332,2 ; Cu =190,5 ; Ni=274,6 ; Pb =82,5 ; Zn =1284,2 mg/ kg) para segunda amostra, resultados estes inferiores aos descritos pela CETESB para amostras de lodo da mesma estação de tratamento. Dada uma potencial utilização deste material como adubo agrícola, foi determinada a fração disponível destes metais. Com exceção do níquel (25%), uma fração pequena dos metais estudados encontra-se na forma assimilável pelas plantas (< 20%), com base no procedimento descrito pela EMBRAPASolos (extração com DTPA). Os efeitos de uma eventual utilização de composto húmico mineral (CHM) como aditivo ao lodo, visando uma redução na fração assimilável de metais, foi estudada em função da quantidade de CHM aplicado e do pH da solução final. Os resultados obtidos demonstraram que o CHM possui um poder de complexação para os metais semelhante ao do DTPA e que, sua aplicação ao lodo de esgoto, teria, na realidade um efeito de potencializar a fração disponível de certos metais como o zinco.
Based on the EPA-3050B procedure, the concentration of metals (Cd, Cr, Cu, Ni, Pb and Zn) in sludge source at CETESB studied. Two samples were analyzed and the results obtained were (Cd =3,4 ; Cr =367,5 ; Cu =263,0 ; Ni=290,6 ; Pb =91,5 ; Zn =1324,9 mg/ kg) and (Cd =3,0 ; Cr =332,2 ; Cu =190,5 ; Ni=274,6 ; Pb =82,5 ; Zn =1284,2 mg/ kg). These concentrations were below those descried by SABESP for sludge samples measured in the same treatment station. Due to the potential utilization of these materials as manure in agriculture, the disposal fraction of these metals was determined. Except nickel (25%), a little fraction of metals studied is assimilated by plants (< 20%), base on the procedure already descried by EMBRAPA- Solos (extraction with DTPA). The effect of an eventual utilization to humic mineral compound (HMC), as additive in sludge, aiming the reduction of the assimilated fraction of metals, were studied in function of both, the amount of HMC applied and the final pH of the solution. The results obtained showed that HMC has a complexation potential for metals similar to DTPA and that, its application in sludge, has in fact, a potential effect on the disposal fraction of metals such as zinc.
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O'Malley, Kristen Marie. "Comparative sensitivity of the early life history stages of the Blue Crab, callinectes sapidus, to mercury exposure". Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/25200.
Testo completo
45
Chapman, Aletia Ann. "Cellular responses to Cd, Pb and Zn in shrews (Myosorex varius and Crocidura flavescens) and BALB/c mice". Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51647.
Testo completoAbstract (sommario):
Thesis (MSc) -- University of Stellenbosch, 2000.ENGLISH ABSTRACT: Shrews are excellent bioindicators of environmental heavy metal pollution. This is due to their diets and the high rate of consumption at which these small mammals consume their prey. Shrews feed mostly on earthworms, and earthworms accumulate high levels of heavy metals in their bodies. Biomarkers measure responses to environmental pollution in the bodies of exposed organisms. Cellular biomarkers give an indication of responses to pollutants at levels of pollutant exposure that are not yet lethal to the organism. This study was prompted by concern that the number of shrews in the Stellenbosch region was declining. For the present study, shrews (Myosorex varius and Crocidura jlavescens) from the Stellenbosch region were sampled. The levels of Cd and Pb in their bodies were analysed in order to ascertain whether or not these two heavy metals, which occur in the environment as a result of various anthropogenic activities, are present in the food chain of the shrews. In the laboratory, shrews were fed live control and metal exposed earthworms from laboratory cultures. The earthworms had been exposed to either Cd or Pb in these cultures over a number of generations. This was performed to determine whether the presence of the metals in the body of the shrews, had resulted from metal accumulation from the earthworms which were fed to the shrews. Cellular biomarkers were used to determine the cellular response to the metals and membrane integrity and DNA integrity were investigated. This was done by exposing the cells of the shrews and ofBALB/c mice to metal salt solutions of Cd, Pb and Zn in vitro. Membrane integrity was tested by cell leaching techniques viz. the LDH assay and the trypan blue assay. DNA integrity was determined by using the comet assay as a biomarker of exposure. The results of the study show that the shrews in the immediate Stellenbosch region are exposed to lower levels of Cd and even lower levels of Pb than shrews from a site 16km out of the town of Stellenbosch. The cellular responses induced by metal exposure of laboratory mice show that the metals are indeed cytotoxic and genotoxic to the cells of small mammals. Cd and Pb were found to be more cytotoxic than Zn, while Zn was more genotoxic than either CqorPb.
AFRIKAANSE OPSOMMING: Skeerbekke is uitstekende bioindikatore van swaarmetaalbesoedeling in die omgewing. Dit is as gevolg van hul dieët en die hoë koers waarteen hierdie klein soogdiere hul prooi verorber. Skeerbekke voed meestalop erdwurms, en erdwurms akkumuleer hoë vlakke van swaarmetale in hul liggaam. Biomerkers meet response as gevolg van omgewingsbesoedeling in die liggame van blootgestelde organismes. Sellulêre biomerkers gee 'n aanduiding van response op besoedelingstowwe by vlakke wat nog nie dodelik is vir die organisme nie. Die studie is aangespoor deur die bekommernis dat die getal van skeerbekkies in Stellenbosch besig is om te daal. In die studie is skeerbekke (Myosorex varius en Crocidura flavescens) van die Stellenbosch omgewing gevang en die vlakke van Cd en Pb in hul liggame gemeet om vas te stelof die twee swaarmetale, wat in die omgewing beland as gevolg van verskeie antropogeniese aktiwiteite, teenwoordig is in die voedselketting van die skeerbekke. Die skeerbekke is in die laboratorium met lewende kontrole en metaalblootgestelde erdwurms uit kulture in die laboratorium gevoer. Die erdwurms is aan Cd en Pb oor baie generasies blootgestel in hierdie kulture. Dit is gedoen om vas te stelof die teenwoordigheid van die metale in die liggame van die skeerbekke 'n oorsaak is van metaalakkumuleering as gevolg van die erdwurms waarmee hulle gevoer is. Sellulêre biomerkers is gebruik om sellulêre respons op die metale op die membraanintegriteit en DNA-integriteit vas te stel. Dit is gedoen deur die selle van skeerbekke so wel as BALB/c muise in vitro bloot te stel aan metaalsoutoplossings van Cd, Pb en Zn. Membraanintegriteit is getoets deur selmembraan permeabiliteit tegnieke nl. die LDH en tripaan blou toetse. DNA-integriteit is getoets deur die komeettoets te gebruik. Die resultate van die studie dui daarop dat die skeerbekke van Stellenbosch aan laer vlakke van Cd, en nóg laer vlakke van Pb blootgestel is as die skeerbekke van 'n perseel 16km buite die dorp. Die sellulêre response geïndusseer deur blootstelling aan metale by die laboratoriummuise het aangetoon dat die metale inderdaad skadelik is vir die selmembraan en die DNA van die selle van die muise. Cd en Pb is meer toksies vir die selmembraan as Zn, terwyl Zn weer meer toksies is vir die DNA-integriteit as Cd en Pb.
46
Stitzer, Linda Schnabel. "THE EFFECT OF SEVERAL ALCOHOL SOLVENTS ON THE MOVEMENT OF CADMIUM, NICKEL AND ZINC THROUGH THREE SOILS (HEAVY METALS, ORGANICS)". Thesis, The University of Arizona, 1985. http://hdl.handle.net/10150/275329.
Testo completo
47
Tani, Fahima. "Zinc and copper uptake by wheat and buckwheat under two transpiration rates". Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=79142.
Testo completoAbstract (sommario):
Wastewater has become a vital new supply for irrigation; however, concerns are mounting about environmental and health hazards related to heavy metals present in wastewater. Experiments were conducted to evaluate wheat ( Triticum aestivum L.) and buckwheat (Fagopyrum esculentum L.) uptake of copper (Cu) and zinc (Zn).Some 15 plants per pot were allowed to establish themselves in the greenhouse for 4 and 6 weeks for buckwheat and wheat, respectively. Plants were then transferred to one of two growth chambers differing in the vapor pressure deficit (VPD), creating conditions for two different transpiration rates to occur: high (HT) and low (LT). A total 48 pots for each crop were seeded in order to evaluate the effect of 8 treatment combinations of Cu and Zn (0/0, 5/0, 15/0, 30/0, 0/25, 5/25, 15/25, 30/25) levels (mg L-1). Treatments were laid out in a completely randomized design within each growth chamber.
Three plants were harvested from each pot at days 10 and 20 for wheat, and days 6, 12 and 18 days for buckwheat to measure dry mass and Cu and Zn content in different plant parts. Heavy metal treatments had no significant effect on transpiration rate for either crops. The higher transpiration rate increased Cu/Zn uptake. A Zn amendment in the absence of Cu had a beneficial effect on buckwheat growth, whereas with Cu at 15 mg Cu L-1 or 30 mg Cu L-1 the lowest dry weights were recorded, regardless of the transpiration rate. Roots contained greater concentrations of Cu and Zn, irrespective of the treatment level and transpiration rate, than did stems, leaves or grain. High retention of heavy metals in the roots of cereal crops may be desirable because these parts are not generally utilized as food or feed.
48
Nightingale, Leigh. "The toxic effect of heavy metals on algal biomass (Spirulina sp.) and carbonic anhydrase activity, an enzyme which is central to algal application in metal precipitation". Thesis, Rhodes University, 2004. http://hdl.handle.net/10962/d1007858.
Testo completoAbstract (sommario):
Acid rmne drainage (AMD) is a major pollution problem througbout the world, adversely affecting both surface and groundwaters. AMD is principally associated with the mining of sulphide ores. The most commonly associated minerals being sulphur, copper, zinc, silver, gold, lead and uranium. As conventional methods for removing heavy metals from wastewater are often prohibitively expensive, the implementation of biological processes for the removal of heavy metals has become a realistic practice. The objectives of this project was firstly to establish the effect of copper, lead and nickel, heavy metals commonly found in AMD waters, on the enzyme carbonic anhydrase, which is an integral part of the carbon concentrating mechanism (CCM) and secondly, to determine the feasibility of using the alkalinity generated by Spindina for the precipitation of heavy metals from solution. Initially, batch flask experiments were performed and it was found that the algae were able to utilise the bicarbonate supplied in the medium, under CO, limiting conditions, through the induction of their CCM, resulting in the generation of carbonate. The effect of the inhibitors, acetazolamide (AZ) and ethoxyzolamide (EZ), were also investigated in order to determine the importance of carbonic anhydrase (CA) in inorganic carbon accumulation and photosynthesis. Results obtained were consistent with those observed in literature and it was found that at IOOf.LM AZ and EZ, complete inhibition of photosynthesis and carbonic anhydrase occurred, with no oxygen being evolved. The results obtained from the inhibitor experiments substantiate the findings that carbonic anhydrase is an important part of the CCM, and that the dehydration of bicarbonate to carbon dioxide and hydroxide ions, is in fact an enzymatic process regulated by the enzyme carbonic anhydrase and is essential for efficient photosynthesis. The effect of heavy metals on Spirulina was also investigated. Lead, copper and nickel were all found to cause a reduction in the synthesis of chlorophyll a, which resulted in a decrease in photosynthetic efficiency and eventually death of the culture. The morphology of the algae was also severely affected by heavy metals, with degradation and aJmost complete disintegration of the algal filaments occurring. Using the Wilbur-Anderson assay method, carbonic anhydrase activity was found to be lower in the experimental flasks containing heavy metals, than the control flasks, reducing the algae's ability to utilise the bicarbonate in solution for effective photosynthesis. The Wilbur-Anderson assay method did not prove to be a reliable method for measuring changes in enzyme activity as results were found to be erratic. Therefore attempts were made to use an oxygen electrode as an alternative method for determining the effects of various parameters on enzyme activity and photosynthesis, this proved to be more successful. Because of the toxic effects of heavy metals on Spirulina it was decided that the use of the biogenic alkalinity generated by the algae for the precipitation of heavy metals may be successfully employed as an alternative method for bioremediation and metal recovery. Carbonate reacts readily with metals, therefore the carbonate produced by this algal system was used for the precipitation of metals. It was possible to categorise the precipitation reactions observed into three groups, namely those metals which, a) precipitate as hydroxides, b) precipitate as carbonates generated from the dissociation of bicarbonate and c) metals which can only precipitate if there is free carbonate present in solution.
49
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
50
Lai, Mei-yee, e 黎美兒. "Fractionation, mobilization and bioaccumulation of heavy metals and mineralogical characteristics of the Mai Po Inner Deep Bay mudflat". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B29980069.
Testo completo