Dissertations / Theses on the topic 'Heavy metals – Physiological effects'
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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.
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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.
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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.
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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/.
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De, Angelis Fabien. "Characterization of proteins involved in RND-driven heavy metal resistance systems of Cupriavidus metallidurans CH34." Doctoral thesis, Universite Libre de Bruxelles, 2010. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210154.
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Les systèmes d’efflux tripartite de type Resistance, Nodulation and cell-Division (RND) sont essentiels dans le maintien de phénotypes de résistance multidrogues et contre les métaux lourds dans nombreuses bactéries Gram-négatives. Le transport de ces composés toxiques hors de la cellule est permis par l’assemblage d’une protéine de type antiporteur cation/proton (unité RND) insérée dans la membrane interne, connectée à une protéine insérée dans la membrane externe, pour former un canal de sorti qui traverse l’entièreté de l’enveloppe cellulaire. Le troisième composant du système, la protéine de type membrane fusion protein (MFP) qui est aussi appelée periplasmic adaptor protein (PAP), est requis pour permettre l’assemblage de tout ce complexe à trois composants. Cependant, les MFPs sont supposées jouer un rôle important et actif dans le mécanisme d’efflux du substrat. Pour mieux comprendre le rôle des MFPs au sein des systèmes d’efflux de type RND, nous avons étudié les protéines ZneB (précédemment appelée HmxB) et SilB, les composants périplasmiques des systèmes ZneCBA et SilABC responsables de la résistance aux métaux lourds chez Cupriavidus metallidurans CH34. Nous avons identifié la spécificité de liaison au substrat de ces protéines, montrant leur capacité à fixer le zinc (ZneB), ou le cuivre et l’argent (SilB). De plus, nous avons résolu la structure cristalline de ZneB à une résolution de 2.8 Å dans la forme apo- et avec un ion zinc fixé. La structure de ZneB possède une architecture générale composée de quatre domaines caractéristiques des MFPs, et la présence du site de coordination au zinc dans une région très flexible à l’interface des domaines β-barrel et membrane proximal. Les modifications structurales que la protéine subit lors de la fixation du zinc on été observée dans le cristal mais aussi en solution, ce qui suggère un rôle actif des MFPs dans le mécanisme d’efflux des métaux, vraisemblablement via la fixation et le relargage de l’ion à l’antiporteur. Les études de sélectivité de transport des antiporteurs ZneA et SilA montre que ces dernières et leurs protéines périplasmiques respectives ont des affinités similaires pour les métaux lourds. De plus, les études de transport ont apportés des arguments en faveur de l’hypothèse de capture cytoplasmique du substrat par l’antiporteur, tandis que la capacité des protéines périplasmiques à fixer les métaux lourds a apporté des arguments en faveur de l’hypothèse de capture périplasmique du substrat par l’antiporteur. Les deux modes de capture pourraient en réalité coexister ;cependant, le débat autour du compartiment cellulaire de capture du substrat par l’antiporteur est complexe et requiert de plus amples efforts afin d’être cerné. / Tripartite resistance nodulation cell division (RND)-based efflux complexes are paramount for multidrug and heavy metal resistance in numerous Gram-negative bacteria. The transport of these toxic compounds out of the cell is driven by the inner membrane proton/substrate antiporter (RND protein) connected to an outer membrane protein to form an exit duct that spans the entire cell envelope. The third component, a membrane fusion protein (MFP) also called periplasmic adaptor protein, is required for the assembly of this complex. However, MFPs are also proposed to play an important active role in substrate efflux. To better understand the role of MFPs in RND-driven efflux systems, we studied ZneB (formerly HmxB) and SilB, the MFP components of the ZneCAB and SilABC heavy metal RND-driven efflux complexes from Cupriavidus metallidurans CH34. We have identified the substrate binding specificity of the proteins, showing their ability to selectively bind zinc (ZneB), or copper and silver cations (SilB). Moreover, we have solved the crystal structure of the apo- and the metal-bound forms of ZneB to 2.8 Å resolution. The structure of ZneB displays a general architecture composed of four domains characteristic of MFPs, and it reveals the metal coordination site at the very flexible interface between the β-barrel and the membrane proximal domains. Structural modifications of the protein upon zinc binding were observed in both the crystal structure and in solution, suggesting an active role of MFPs in substrate efflux possibly through binding and release. The selectivity assays of the antiporter proteins ZneA and SilA demonstrated similar specificities in relation to their cognate MFPs toward heavy metal cations. Moreover, antiporter transport assays provide evidence for cytoplasmic substrate capture by this protein, whereas MFP substrate binding provides evidence for periplasmic substrate capture. Therefore, both modes of capture might co-exist; nevertheless, the substrate capture issue is a complex topic still needing consequent efforts to understand it.Doctorat en Sciences agronomiques et ingénierie biologique
info:eu-repo/semantics/nonPublished
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Carvalho, Marcia Eugenia Amaral de. "Integrated approach of anatomical, physiological and biochemical parameters for the study of tolerance mechanisms to cadmium in tomato accessions." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/11/11137/tde-09102017-172803/.
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Tomato (Solanum lycopersicum L.) consumption has increased every year due to the fruit attractiveness, several utilizations, and beneficial effects for human health. However, tomato fruits can accumulate a Cd concentration that exceeds the safety threshold for human consumption of vegetables, even when plants are grown in soil with acceptable Cd level. Cd is a non-essential, hazardous element to biological systems, triggering several diseases in humans. In plants, Cd disturbs the antioxidant machinery, changes the nutritional status, and impairs the photoassimilate production and/or partitioning, hence reducing fruit yield and quality. However, distinct tomato accessions can present contrasting tolerance degree to Cd toxicity, as detected by our group in previous studies. The use of these accessions is a powerful approach to identify strategies employed by plants to cope with Cdinduced challenges, and the acknowledgement of such strategies can be potentially used in breeding and biotechnological programs to improve fruit yield and quality in crops that were cultivated in contaminated fields. The set of studies that compose the present thesis aimed (i) to identify the main mechanisms for the contrasting tolerance degree to Cd-induced toxicity in tomato accessions after short and long-term Cd exposure; (ii) to evaluate the relationship among tolerance degree and fruits attributes in plants that were grown in Cd-containing soil, and (iii) to determine the transgenerational effects of Cd-induced stress. In the first experiment, nine tomato accessions with a varied tolerance degree, which was based on biomass accumulation, to Cd exposure were grown in hydroponic solution containing CdCl2 35 μM for 6 days. Avoidance of high Mg concentration in roots was identified as a plant strategy to mitigate Cd toxicity by preventing formation of root hairs. Regarding the mode of action of Cd toxicity, Mn excess in leaves, in addition to the high Cd concentration per se, seems to be coupled to leaf damages that are enhanced by the increased Zn and B concentrations in the photosynthetic tissues. In the second experiment, tolerant (Yoshimatsu) and sensitive (Tropic Two Orders) genotypes were grown in Cd-containing soil, in order to evaluated production parameters. After plant exposure to Cd, the tolerant genotype presented an increased fruit diameter, height and weight, when compared to the control plants. In both cultivars, Cd concentration varied according to the following descending order: roots = leaf blade > (floral receptacle, peduncle and sepals) > stem = fruit peel = fruit pulp. Moreover, data suggested that floral receptacle and its related-structures acted as a barrier to the Cd transportation to the fruits, but it was not enough to avoid Cd reaching the fruits. Furthermore, Cd exposure provoked remarkable reductions in the Mg concentration in roots of sensitive and tolerant genotypes, revealing that both tomato cultivars are able to employ this mechanism for plant acclimation to long-term Cd exposure. Considering such information, it is possible that, under the short-term Cd exposure, tolerant accessions activate this mechanism either early or faster than sensitive genotypes. In addition, positive transgenerational effects on seed germination and vigor of the tolerant genotype were triggered by the plant-mother cultivation in Cd-containing media, despite of the increased chromosomal abnormality. This work reported new insights about the effects of Cd exposure on tomato development, tolerance mechanisms, fruit quality and yield of tomato, as well as Cd distribution in the plants.O consumo de tomate (Solanum lycopersicum L.) tem aumentado a cada ano devido a atratividade dos frutos, suas diversas utilizações e efeitos benéficos para a saúde humana. No entanto, os frutos de tomate podem acumular uma concentração de cádmio (Cd) que excede o limiar de segurança para o consumo humano, mesmo quando as plantas são cultivadas em solo com níveis aceitáveis de Cd. Cádmio e um elemento não-essencial, extremamente perigoso para os sistemas biológicos, desencadeando varias doenças em seres humanos. Nas plantas, o Cd perturba a maquinaria antioxidante, altera o estado nutricional e prejudica a produção e /ou o particionamento de fotoassimilados, frequentemente reduzindo a produtividade e qualidade de frutos. No entanto, diferentes acessos de tomateiros podem apresentar contrastantes graus de tolerância a toxicidade gerada pela exposição ao Cd, como detectado em estudos anteriores de nosso grupo. O uso desses acessos e uma abordagem poderosa para identificar as estratégias empregadas pelas plantas para lidar com os desafios induzidos pelo Cd; e o conhecimento de tais estratégias pode ser potencialmente utilizado em programas biotecnológicos e de melhoramento genético. Deste modo, o conjunto de estudos que compõem a presente tese objetivou (i) identificar os principais mecanismos que suportam o grau de tolerância contrastante a toxicidade induzida por Cd em acessos de tomate após exposição a curto e longo prazos a este metal pesado; (ii) avaliar a relação entre o grau de tolerância e os atributos físico-químico de frutos oriundos de tomateiros cultivados em solo contendo Cd, e (iii) determinar os efeitos transgeracionais do estresse induzido por Cd. No primeiro experimento, nove acessos de tomateiro com graus variados de tolerância a exposição ao Cd, baseado na acumulação de biomassa, foram cultivados em solução hidropônica contendo 35 μM de CdCl2 durante 6 dias. O impedimento de elevada concentração de magnésio (Mg) em raízes foi identificado como possível estratégia da planta para mitigar a toxicidade de Cd, por meio da evitação da formação de pelos radiculares. Em relação ao modo de ação da toxicidade induzida por Cd, o excesso de Mn, em adição a elevada concentração de Cd, parece estar acoplado aos danos foliares que são acentuados ainda mais pelas altas concentrações de zinco (Zn) e boro (B) nos tecidos fotossintéticos de plantas sob exposição ao Cd. No segundo experimento, os genótipos tolerantes (Yoshimatsu) e sensíveis (Tropic Two Orders) foram cultivados em solo contendo Cd, a fim de avaliar os parâmetros de produção. O genótipo tolerante apresentou frutos com maior diâmetro, altura e peso após o cultivo em solo contendo Cd, quando comparado as plantas controle. Em ambas as cultivares, a concentração de Cd variou de acordo com a seguinte ordem descendente: raízes = folíolos> (receptáculo floral, pedúnculo e sépalas) > caule = casca de fruta = polpa de fruta. Alem disso, dados sugerem que o receptáculo floral e suas estruturas atuaram como uma barreira ao transporte de Cd para os frutos, entretanto, ela não foi suficiente para evitar que o Cd atingisse os frutos. Em adição, a exposição ao Cd provocou notáveis reduções na concentração de Mg nas raízes de genótipos sensíveis e tolerantes, revelando que a aclimatação das plantas depende do baixo status de Mg em tecidos radiculares. Desde que ambas as cultivares são capazes de empregar este mecanismo, os dados sugerem que, durante a exposição a curto prazo ao Cd, acessos tolerantes são capazes de ativa-lo ou mais cedo ou mais rápido do que acessos sensíveis. Ademais, efeitos transgeracionais positivos na germinação e vigor das sementes do genótipo tolerante foram desencadeados pelo cultivo planta-mãe em solo com Cd, apesar do aumento de anormalidades cromossômicas. Este trabalho reportou novos conhecimentos sobre os efeitos da exposição ao Cd sobre o desenvolvimento do tomateiro, mecanismos de tolerância, qualidade e rendimento de frutos, bem como a distribuição de Cd dentro da planta.
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Mgobozi, Vuyokazi. "Heavy metal content absorption and medicinal potential of Egeria densa (Planch.) Casp." Thesis, University of Fort Hare, 2013. http://hdl.handle.net/10353/d1013121.
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The contamination of heavy metals in the environment is a looming concern worldwide. Egeria densa (Planch) (Submerged aquatic plant) from two ponds: Site A with co-ordinates (32º 48’22.04”S; 26°48’58.79” E) and Site B with co-ordinates (32°48’33.25”S; 26°48’33.25”S) in Alice (Eastern Cape) was evaluated for its ability to absorb heavy metals, phytochemical constituents, antimicrobial activity and ultra-structure using standard analytic procedures. Cadmium (Cd), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), and zinc (Zn) were measured in water, sediments and plant. The concentrations of these metal elements were determined with use of Inductively Coupled Plasma- Optical Emission Spectrometry (ICP-OES). In sediments, the heavy metals (mg/kg) decreased in the order of their average concentration as follows: Fe (40.320) > Zn (1.259) > Pb (0.564) > Mn (0.186) > Cu (0.037) in Pond 1 whereas in Pond 2 Fe (61.527) > Cd (0.999) > Mn (0.648) > Pb (0.586) > Zn (0.156) > Cu (0.045). The highest concentration of Fe was detected in both sites and Cu being the least. The concentrations of the metals in the plants sample (from Pond 1) were found in order of Mn > Pb > Cu > Fe whereas cadmium and zinc were not detected, while the concentration in Pond 2 decreases in order of Zn > Mn > Pb > Cd > Fe > Cu. In the water samples, concentrations of heavy metals (mg/L) decreased in the order of their average concentrations as follows: Pb (35.36) > Fe (3.07) > Mn (0.238) > Cu (0.104), both cadmium and zinc were below the limit of detection in Pond 1, whereas in Pond 2 the concentrations decreased as follows: Pb (13.033) >Fe (1.69) > Cu (0.270) > Mn (0.248) > Cd (0.004) and Zinc was not detected. Phytochemical analyses of the plant extracts revealed the presence of phenols, flavonoids, proanthocyanidin, flavonols, saponins, alkaloid and tannins in all the extracts (water, acetone and n-hexane). Both acetone and water extracts, showed high concentration of proanthocyanidin, while tannin was the lowest in acetone extract. Antimicrobial evaluation using, Gram positive (Staphylococcus aureus, Bacillus pumilus, Bacillus cereus, Streptococcus pyogenes, Enterococcus faecalis) and Gram negative (Klebsiella pneumonia, Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris and Serratia marcescens) bacteria showed negative results for all the strain, except Streptococcus pyogenes which was inhibited at MIC of 0.1 mg/ml. Scanning electron microscopy (SEM) of ultra-structure of Egeria densa, showed that certain bacteria attached to the leaf, However more work has to be done on E. densa to verify the mechanism by which it accumulates heavy metals. The study shows that E. densa has a potential of accumulating heavy metals especial Manganese in plant.
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Kong, In-Chul. "The effects of heavy metals on anaerobic biotransformation reactions." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/25228.
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Ressing, Sara Marlene. "Effects of heavy metals on two small mammal species." OpenSIUC, 2012. https://opensiuc.lib.siu.edu/theses/947.
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Research on the chronic effects of toxic chemicals on individuals, populations, communities, and ecosystems is imperative to regulate pollutants and preserve threatened species and habitats. I designed a two-pronged study to investigate the effects of heavy metal contaminants on small mammal populations, communities and body condition. To compare population and community metrics, I conducted a year-long mark-and-release study from over 5,400 trap nights on a contaminated and reference site within Crab Orchard National Wildlife Refuge, a Superfund site. During the second phase, I compared contaminant residues to body condition in 29 white-footed mice (Peromyscus leucopus) and 21 southern short-tailed shrews (Blarina carolinensis) from the Refuge and from three reference sites. Body weight, age structure, trapping success or species diversity did not differ between sites. Mice from the contaminated site were more abundant with lower reproduction (as number of juveniles per adult female). Cadmium in both livers and kidneys of mice and shrews was significantly greater on the contaminated site. Elevated renal cadmium in mice (96 ± 79 mg/kg dry weight) and shrews (242 ± 166 mg/kg dry weight) from the contaminated site could likely impair physiologic functions with long-term effects. For white-footed mice, increasing renal copper, lead, and nickel were good predictors of low ash, water, and protein but did not correlate significantly with crude lipid content. In shrews, however, metals either showed no relationship or, in the case of renal cadmium and copper were positively related to body condition as increased protein content. Simply comparing animals from reference versus contaminated sites provided few insights into overall community structure or population dynamics of white-footed mice. While metals explained as much as 40% of body condition (ash) in mice, findings in both species are counter-intuitive or refute predictions. Future studies should include manipulative field experiments that pair higher-resolution, biologic responses such as histologic and biomarker assays with population and community dynamics.
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Schoeman, Werner. "Cellular stress responses to cadmium contamination as measure of sensitivity in intertidal molluscan species." Thesis, Link to the online version, 2007. http://hdl.handle.net/10019/460.
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Al-Ghamdi, H. S. H. H. "Studies on the effects of heavy metals on freshwater crustacea." Thesis, Swansea University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.635672.
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The effects of cadmium and zinc ions upon the longevity of two freshwater crustaceans, Daphnia pulex (de Geer) and Cyclops fuscus (Jurine) were examined at temperatures (8°C, 14°C, and 21°C). Winter collected speciments of both species were found to be more resistant than summer collected specimens. In both species Cd^++ was more resistant than Zn^++ and resistance to both metal ions was greater in C.fuscus than in D.pulex. Temperature has a synergistic effect on the toxicity of both metals to both species. The pH influence on the toxicity of Cd^++ and Zn^++ to D.pulex was examined. The toxicity of both metals increased with increasing acidity. Acidity alone was lethal to D.pulex with no Cd^++ or Zn^++ added. Cadmium and zinc were accumulated by D.pulex to high concentrations in proportion to time and concentration in solutions. Cadmium accumulations were lower than zinc. The major sites of accumulation, tested using Zn^65 were the gut, hepatopancreas and exoskeleton of D.pulex. The respiratory rate of D.pulex and C.fuscus were affected by the presence of CD^++ and Zn^++, but D.pulex was more affected than C.fuscus, and cadmium effect was generally more than zinc ions. The ultrastructural changes in the hepatopancreas of D.pulex were examined after exposure to cadmium ions. The hepatopancreatic cell was affected. Mitochondria were the most affected organelles.
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Linnane, Kevin. "The effects of heavy metals on marine algae - animal interactions." Thesis, University of Newcastle Upon Tyne, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440576.
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Milton, Adrian Mark. "Heavy metals in contaminated grassland ecosystems : distribution, transfer and effects." Thesis, University of Liverpool, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266222.
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Day, A. D., B. B. Taylor, I. L. Pepper, and M. M. Minnich. "Effects of Sewage Sludge on Heavy Metals in Cotton Seed." College of Agriculture, University of Arizona (Tucson, AZ), 1988. http://hdl.handle.net/10150/204508.
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In 1987, seed samples from three cotton fields in Avra Valley, Arizona, grown with liquid sewage sludge and inorganic nitrogen fertilizer, were analyzed for five heavy metals. Concentrations of cadmium, copper, lead, nickel, and zinc were similar in cotton seeds fertilized with either sewage sludge or inorganic nitrogen fertilizer. The levels of all five metals were well below the allowable EPA limits.
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Braaf, Ryan. "Zirconium-induced physiological and biochemical responses in two genotypes of Brassica napus L." University of the Western Cape, 2015. http://hdl.handle.net/11394/4874.
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>Magister Scientiae - MScSouth Africa is one of two countries responsible for the production of approximately 80% of the world’s Zr. The increase in mining activity has detrimental effects on the environment, especially crop plants, as more pollutants are leached into the soil. Consequently, it is necessary to understand how plants respond to this form of abiotic stress. Therefore, this study focused on determining the physiological and biochemical responses of two genotypes of Brassica napus L (Agamax and Garnet) in response to Zr stress. The levels of cell death, lipid peroxidation and ROS were higher in Garnet, whereas the chlorophyll content was higher in Agamax. Furthermore, native PAGE analysis detected seven SOD isoforms and seven APX isoforms in Agamax, compared to 6 SOD isoforms and 7 APX isoforms in Garnet. The results thus indicate that Agamax is tolerant to Zr-induced stress, whereas Garnet is sensitive. An assay for the rapid quantification of Zr within plant samples was subsequently developed, which revealed that Agamax retained the bulk of the Zr within its roots, whereas Garnet translocated most of the Zr to its leaves. The ability of Agamax to sequester Zr in its roots comes forth as one of the mechanisms which confers greater tolerance to Zr-induced stress. As a consequence, our study sought to use the optical, physical and chemical properties of quantum dots to image the uptake and translocation of Zr in B. napus genotypes. ICPOES was also performed to quantify Zr levels in various plant organs. Data from the ICPOES revealed varying patterns of uptake and translocations between Garnet and Agamax. These patterns were similarly shown in IVIS Lumina images, tracing the transport of QD/Zr conjugates. This method ultimately proved to be successful in tracing the uptake of Zr, and could essentially be a useful tool for targeting and imaging a number of other molecules.
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Aigbavbiere, Ernest. "The effects of heavy metals on denitification in a wetland sediment." Thesis, Linköping University, Department of Water and Environmental Studies, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7884.
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Wetlands water quality is influenced by the anthopogenic activities in the catchments’ areas. Wastewaters from the urban storm, agricultural runoff and sewage treatment often end up in wetlands before flowing to rivers, lakes and the sea. A lot of pollutants are readily transported in these wastewaters, thus subjecting the wetland ecosystem into a continuous resilience. Importantly, heavy metals like Cu, Zn, and Pb etc. are constituents of such pollutants in the wastewaters.
The study has as a specific objective to investigate the effects of heavy metal Cu, Zn and Pb on denitrification, an important ecosystem process and service. In a wetland situation, denitrification is a permanent nitrogen removal process accounting for about 90% of the total nitrogen removal.
The research was carried out in the laboratory and sediment samples were taken from a constructed wetland in Linkoping. We employed acetylene inhibition technique in obtaining N2O as a product resulting from nitrate reduction. The treatments (Cu, Zn and Pb) levels were 100 mg/kg, 250 mg/kg, 500 mg/kg and 1000 mg/kg of sediment, in three replicates and a control.
Samplings of the assay were taken within 24hours. Gas chromatography was used to analyse and quantify N2O in the various samples. A linear regression analysis was carried out with Windows Excel and SPSS to compare the various treatments with the control at 95% confidence level.
The results show that there were no inhibitions of denitrification at 100 mg/kg sediment treatment level for any of the element. Inhibition of denitrification was observed at treatment levels 500 mg/kg and 1000 mg/kg of sediment. The rate of nitrate reduction was compared from the slope of the regression curve. The rate for Cu at 500 mg and 1000 mg /kg of sediment was moderately related to that of the control, Zn shows a similar trend but a higher rate in some samples, while Pb shows more inhibition.
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Yang, Shu. "Effects of heavy metals and phosphorus on nitrate removal in constructed wetlands." Thesis, Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-15550.
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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.
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Tasneem, Sameera. "EFFECTS OF ENVIRONMENTAL HEAVY METALS ON NERUAL STEM CELL SURVIVAL AND DIFFERENTIATION." Cleveland State University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=csu1400500632.
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Lategan, Kim Leigh. "The in vitro effects of heavy metals and nanoparticles on the immune system." University of the Western Cape, 2017. http://hdl.handle.net/11394/6209.
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Philosophiae Doctor - PhD (Medical BioScience)Heavy metals and nanoparticles may be released into the environment due to their use and applications. Sources of high, toxic metal concentrations may result from leachates from hazardous waste sites, discharge from industrial plants, and effluents from wastewater treatment plants being released into the environment. Nanoparticles may be found in a number of consumer products, and are used in medical applications such as drug delivery, bioimaging and biosensing. The release of heavy metals and nanoparticles to the environment may directly or indirectly impact abiotic and biotic systems. Three heavy metals and three nanoparticles were selected for this study. The heavy metals selected include cadmium (Cd), silver (Ag) and copper (Cu). The nanoparticles (NPs) chosen were silver nanoparicles (AgNPs), graphene oxide nanoparticles (GONPs) and carbon dots (CDs). These compounds were selected to evaluate the potential effects these compound may have on the immune system. The murine macrophage cell line RAW 264.7 and human whole blood cell cultures (WBCs) were selected as immune system representatives to assess the effects of heavy metals and nanoparticles on the immune system. The effects of heavy metals and NPs on RAW cells were monitored either in the absence or presence of the mitogen, lipopolysaccharide (LPS). The effects of heavy metals and NPs on WBCs were evaluated under basal conditions or in the presence of LPS or phytohaemmagglutinin (PHA). A number of parameters were monitored.
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Coelho, Renato Ruas Pereira. "Effects of metals on the root-cell water relations of Vicia faba and Zea mays." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388754.
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De, Sa Paul Agnelo. "Effects of boundaries and impurities on critical systems." Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282332.
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Woodcock, Thomas Stuart. "Effects of Roadway-Related Physical and Chemical Habitat Alterations on Stream Ecosystems." Fogler Library, University of Maine, 2002. http://www.library.umaine.edu/theses/pdf/WoodcockTS2002.pdf.
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Khara, Galvin. "Modelling the effects of swift heavy ion irradiation on metals and band gap materials." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10054890/.
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Daka, Erema Ransome. "Population differences in the toxic effects of heavy metals to Littorina saxatilis olivi (prosobranchia: Mollusca)." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.320573.
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Torres, Eric M. "Microalgae Sorption of Ten Individual Heavy Metals and their Effects on Growth and Lipid Accumulation." DigitalCommons@USU, 2016. https://digitalcommons.usu.edu/etd/4956.
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As underdeveloped nations continue to industrialize and the world population continues to increase, the need for energy, natural resources, and goods will lead to ever increasing heavy metal concentrations in various waste streams that can have damaging effects on plant life, wildlife, and human health. The focus of this study is to understand the impact of individual heavy metals on Nannocholoropsis salina microalgae growth and understand the potential of microalgae to be used as a bioremediation tool for contaminated water systems. Individual metals (As, Cd, Cr, Co, Cu, Pb, Ni, Hg, Se, and Zn) were introduced into growth media. For each metal a baseline concentration was determined based on reported concentrations at various municipal and industrial wastewater sites. In addition to the baseline concentrations, experimentation was conducted at 10X and 40X the baseline to evaluate the potential for severely contaminated systems. Biological growth experimentation was performed in triplicate at the various contaminant concentrations and at 3 different light intensities. Results show nickel significantly reduced growth, while the other metal contaminated systems showed growth between 89% and 99% of the control. Increased heavy metal concentrations resulted in progressively lower growth rates. Lipid analysis shows most baseline metal concentrations slightly decrease or have minimal effects in lipid content. Metals analysis on the biomass showed the majority of the metals in the systems containing Cd, Co, Cu, and Pb were sorbed by the microalgae with minimal metals remaining in the growth media illustrating the effectiveness of microalgae to effectively bioremediate contaminated systems when contamination levels are sufficiently low to not detrimentally impact productivity. Microalgal biomass in the systems containing As, Cr, Ni, and Se showed decreased ability to sorb metal ions. Results show at moderate contamination levels, microalgae can be an effective tool for bioremediation.
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Mitchell, Kirsty. "The transfer of heavy metals through trophic levels and their toxicity effects on organisms including humans." Thesis, Nottingham Trent University, 2007. http://irep.ntu.ac.uk/id/eprint/215/.
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This research has investigated a number of topics pertaining to the effects of metalliferous mining. The combination of these has shown that past mining activities and their resultant waste have led to the accumulation of metals through trophic levels. During visits to Blanchdown Wood, Devon, UK and Snailbeach, Shropshire, UK, samples were collected to examine the effects of the spoil tips on the surrounding ecosystem. Samples of vegetation, soil and animal materials were extracted and analysed by inductively coupled plasma-optical emission spectrometry for the presence of heavy metals and were found to contain varying concentrations of lead, copper, arsenic, tin, tungsten and zinc. Laboratory investigations followed to determine the toxicity effects of lead, copper, and tungsten on Pandorina morum. This demonstrated that although single elements have effects on population growth, a combination of the three cations had pronounced and cumulative effects. It was found that the algae reduced the concentration of lead in the nutrient media, but it was not possible to determine whether lead was accumulated by the algae or adhered to the surface of the cells. In either case it is hypothesized that lead could then be transferred to the succeeding trophic levels. Further samples examined included archaeological finds, such as Anglo-Saxon human skeletons from a non-mining area. The concentrations of lead in these samples indicated that the population had been exposed to lead, and this is further explored. Since the population resided in a non-mining area, it is suggested that the contaminant was ingested via trophic level inputs; thus, providing further evidence certain metals are available to be transferred through the trophic levels to be stored in the human skeleton.
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Mahmoud, Huda Mahmoud Abdullah. "Structural and functional diversity of epilithic bacterial communities in streams : effects of pollution." Thesis, University of Hull, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.271992.
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Venter, Chantelle. "An in ovo investigation of the cellular effects of the heavy metals cadmium and chromium alone and in combination." Diss., University of Pretoria, 2014. http://hdl.handle.net/2263/46019.
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Many heavy metals are essential for biological functions; however some of these metals,
especially at high concentrations, can have serious adverse effects on humans. The main
sources of heavy metal exposure are through agriculture, transport, mining and related
operations. South Africa has a thriving mining industry and is known for its rich mineral
resources, but due to the incorrect method of disposal of the waste from these mines,
substances, including heavy metals, get into the water and air supply, affecting the people
living in close proximity to these mines. Exposure is through inhalation of contaminated air
and consumption of contaminated food and water. The most vulnerable to heavy metals are
the developing fetus, because of the high rate of cell division and differentiation.
In the current study, two heavy metals cadmium (Cd) and chromium (Cr) were chosen based
on the possibility of being exposed to them in South Africa. Thus, the aim of this study was
to investigate the possible cellular effects of the heavy metals Cd and Cr alone and in
combination, at different concentrations, on brain, liver and kidney tissue by using a chick
embryo model.
This model was successfully implemented over a 14 day period after which the embryos
were terminated and the brains, livers and kidneys removed and processed for light- and
transmission electron microscopy (with energy dispersive spectroscopy and electron energyloss
spectroscopy). In addition, the effect of Cd and Cr alone and in combination on DNA
structure and micronuclei formation was evaluated. The levels of the major antioxidant
component, glutathione was determined in the brains of the chick embryos. At low concentration of Cd and Cr alone and in combination, a hormesis effect was observed
in the survival rates and weights of the chick embryos, while at x1000 physiological dose
(PD) Cr and Cd alone and in combination the effects were toxic. The majority of viable
embryos did not have any macro-anatomy abnormalities.
Morphological evaluation of the brain, liver and kidney samples revealed that Cd caused
severe alterations at its highest concentration with minor alterations at the lower
concentrations. Cr and the metal combination groups on the other hand, only caused
minimal alterations throughout the concentration ranges evaluated. The presence of Cd and
Cr alone and in combination in the liver tissue was confirmed with the electron energy-loss
spectroscopy analysis that detected these metals in the nuclei, mitochondria and Golgi
complexes of the hepatocytes. This might contribute to the ultrastructural changes observed
in this organ. The genotoxicity testing on the red blood cells revealed no substantial
differences, as only a few micronuclei were present.
Although heavy metals cause DNA damage through an indirect mechanism of oxidative
damage, the presence of Cd and Cr in the nucleus and mitochondria indicates that these
metals may have a direct effect on DNA structure. With DNA agarose gel electrophoresis it
was found that Cd and Cr alone and in combination caused DNA fragmentation. In the brain,
GSH levels were normal; however changes may be the result of Cd and Cr causing the
depletion of other antioxidant elements such as glutathione reductase, glutathione
peroxidase, superoxide dismutase and catalase.
In conclusion, this study indicates that Cd and Cr alone and in combination are toxic to the
chick embryo. Cd is more toxic than Cr, and both metals accumulate in the nuclei and
mitochondria where they induce damage either through oxidative and/or other mechanisms
associated directly with DNA damage.Dissertation (MSc)--University of Pretoria, 2014.
tm2015
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Arias, Jack A. "Symbiotic effects on the fungus Glomus Sp. on chromium(III), chromium(VI), and lead(II) uptake by mesquite (Prosopis Sp.) a novel method to remediate heavy metals /." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
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Arvapally, Ravi K. "Sensitization of Lanthanides and Organic-Based Phosphorescence via Energy Transfer and Heavy-Atom Effects." Thesis, University of North Texas, 2010. https://digital.library.unt.edu/ark:/67531/metadc28388/.
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The major topics discussed are the phosphorescence sensitization in the lanthanides via energy transfer and in the organics by heavy atom effects. The f-f transitions in lanthanides are parity forbidden and have weak molar extinction coefficients. Upon complexation with the ligand, ttrpy (4'-p-Tolyl-[2,2':6',2"]-terpyridine) the absorption takes place through the ligand and the excitation is transferred to the lanthanides, which in turn emit. This process is known as "sensitized luminescence." Bright red emission from europium and bright green emission from terbium complexes were observed. There is ongoing work on the making of OLEDs with neutral complexes of lanthanide hexafluoroacetyl acetonate/ttrpy, studied in this dissertation. Attempts to observe analogous energy transfer from the inorganic donor complexes of Au(I) thiocyanates were unsuccessful due to poor overlap of the emissions of these systems with the absorptions of Eu(III) and Tb(III). Photophysics of silver-aromatic complexes deals with the enhancement of phosphorescence in the aromatics. The heavy atom effect of the silver is responsible for this enhancement in phosphorescence. Aromatics such as naphthalene, perylene, anthracene and pyrene were involved in this study. Stern Volmer plots were studied by performing the quenching studies. The quenchers employed were both heavy metals such as silver and thallium and lighter metal like potassium. Dynamic quenching as the predominant phenomenon was noticed.
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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.
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Kerrison, P. "Effects of low concentrations of heavy metals on plankton community dynamics in a small, fertile, freshwater lake." Thesis, University of East Anglia, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372349.
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Ashworth, Daniel J. "The effects of dissolved organic matter on the behaviour of heavy metals in sewage sludge-amended soils." Thesis, University of Reading, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394419.
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Mudre, John M. "An analysis of the contamination by and effects of highway- generated heavy metals on roadside stream ecosystems." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/49944.
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This study examined the consequences of the opening and operation of a new highway north of Richmond, Virginia with respect to contamination of the aquatic environment with heavy metals (Zn, Cd, and Pb), and the effects of these metals on the biota of roadside streams. Sixteen sites located on six small, soft-water streams that were crossed by the highway, encompassing six reference sites located upstream of the highway, six sites located directly at the highway, and four sites located downstream of the highway, were sampled over a two and a half year period, allowing both spatial and temporal analyses.
Traffic densities on the highway averaged about 12,000 vehicles per day (vpd). Significant increases in the metals concentrations of sediment, benthic invertebrates, fish whole-bodies, and fish tissues (liver, kidney, and bone) were noted over the course of the study, although the increase varied in magnitude, and were not always consistent. Sediment metals concentrations followed a dynamic plateau. Fish whole-body concentrations of Cd and Pb increased steadily over the course of the study. Spot-sampling for the same parameters along another nearby, more heavily traveled highway (50,000 vpd) indicated that increases in metals concentrations in the different ecosystem components at the study streams would have been greater had there been more traffic.
A number of biotic parameters were investigated to determine whether metals contamination was affecting the biological integrity of the study sites. These were: benthic macroinvertebrate diversity and density; the percentage of the aquatic insect community that was composed of chironomids; and fish community diversity, density, and biomass. Only benthos density, the percent chironomids, and fish species diversity showed changes that could be related to metals contamination. Indications from spot sampling along the more heavily traveled highway were that if more contamination had been experienced, more biotic parameters would have been disturbed, and to a larger extent. Fish community structure analyses using the Pinkham-Pearson coefficient of similarity indicated that fish community structure became increasingly altered at highway sites, and to a lesser degree downstream sites, over the study period.Ph. D.
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Wong, Jayme Nicole. "Ecological Impacts of Mine Pollutants in Patagonia, Arizona: Studying the Effects of Heavy Metals on Aquatic Ecosystems." Thesis, The University of Arizona, 2015. http://hdl.handle.net/10150/578899.
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Mine tailings pollute surrounding waterways with high levels of heavy metals leftover from mining and milling processes. In arid climates like Arizona, these pollutants are transported to surrounding environments and downstream via aeolian transport (wind), and via precipitation from seasonal storms like Arizona's monsoon season. Elemental analyses for invertebrates were conducted twice per year at 8 sites throughout 3 locations in Patagonia, Arizona. The sites were all downstream of a mine, and drained into Patagonia Lake. Elemental analyses for fish were conducted at Patagonia Lake with the same frequency. These were done for 12 heavy metals. Sufficient data was collected only for Dysticidae invertebrates at Alum Gulch, and as expected, our results showed higher levels of heavy metals at our sites post-monsoon season (with the exception of mercury and manganese). This increase in heavy metal concentrations can be attributed to transport by precipitation from monsoonal storms. Increases in heavy metal concentrations were also found for all 12 elements in fish of Patagonia Lake.
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Salt, David Edward. "Copper-binding peptides of Mimulus guttatus." Thesis, University of Liverpool, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.291882.
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Prajzner, Scott P. "Effects of land use change on bee (Anthophila) community structure and function." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1480666062652755.
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Luce, Shelley Lynne. "Stress-induced mortality of juvenile Atlantic salmon (Salmo salar) due to accumulated effects of heavy metals and parasites." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq23847.pdf.
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Chandar, Krishan. "The effects of heavy metals from past applications of sewage sludge on soil microbial biomass and miocrobial activity." Thesis, University of Reading, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293755.
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Howlett, Niall G. "The effects of altered membrane fatty acid composition on the toxic interactions of heavy metals with Saccharomyces cerevisiae." Thesis, Oxford Brookes University, 1998. https://radar.brookes.ac.uk/radar/items/ba46f6e3-f663-49af-9870-96fc8a28bc23/1/.
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The effects of altered membrane fatty acid composition on the toxic interactions of heavy metals with Saccharomyces cerevisiae were examined. Saccharomyces cerevisiae was enriched with the polyunsaturated fatty acids (PUFAs) linoleate (18:2) and linolenate (18:3) by growth in 18:2- or 18:3-supplemented medium. Incorporation of the exogenous PUF As resulted in them comprising greater than 65% and 40% of the total fatty acids in whole-cell and plasma membrane lipids, and nuclear membrane lipids, respectively. Incorporation of the exogenous PUF As had no discernible adverse effects on cell division. However, inhibition of cell division in the presence of Cd(N03)2 was accentuated by growth in the presence of the di-unsaturated fatty acid linoleate. Furthermore, susceptibility to both Cd2+ - and Cu2+ -induced plasma membrane permeabilisation and whole cell toxicity was markedly accentuated in PUF A-enriched cells, and increased with the degree of fatty acid unsaturation. The increased sensitivity ofPUFA-enriched cells to membrane permeabilisation and whole-cell toxicity was correlated with increased levels of lipid peroxidation in these cells. Cu2+ - and Cd2+_ induced lipid peroxidation was rapid and associated with a decline in plasma membrane lipid order, detected by fluorescence depolarization measurements. Levels of the lipid peroxidation products thiobarbituric acid-reactive substances (TBARS) and conjugated dienes were markedly higher in PUF A-enriched cells, compared with unsupplemented cells, following exposure to cadmium or copper. Thus, lipid peroxidation was demonstrated as a major means of heavy metal toxicity in a microorganism for the first time. In addition, the effects ofPUFA-enrichment on the interactions of heavy metals with cellular nucleic acids were examined. Exposure ofPUFA-enriched cells to the redox-active metals chromium and copper resulted in the uncoupling of DNA synthesis from cell division, leading to sequential S phases. For example, DNA levels of up to 8C were evident in 18:3-enriched cells after only 4.5 h exposure to 100 JJ.M Cu(N03h. Using flow cytometry, the heterogeneity in susceptibility to copper toxicity of exponential phase S. cerevisiae was also examined. Susceptibility towards copper toxicity was demonstrated to be cell cycle stage-dependent, whereby G2/M phase cells were found to be the most susceptible towards copper toxicity. Staining with the oxidantsensitive probe 2',7' -dichlorodihydrofluorescein diacetate (H2DCFDA) revealed that the greater copper sensitivity of G2/M phase cells correlated with elevated endogenous levels of reactive oxygen species in these cells.
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Åkerblom, Staffan. "Anthropogenic heavy metals in organic forest soils : distribution, microbial risk assessment and Hg mobility /." Uppsala : Department of Environmental Assessment, Swedish University of Agricultural Sciences, 2006. http://epsilon.slu.se/200667.pdf.
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Bhika, Akaashni Nareschandra. "An ex vivo erythrocyte study : the protective effects of antioxidants against the toxicity of heavy metals in cigarette smoke." Diss., University of Pretoria, 2017. http://hdl.handle.net/2263/65852.
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Besides environmental exposure to metals, cigarette smoke either primary or secondary also contributes to metal exposure. This exposure in South Africa as well as in the rest of the world is increasing. Exposure to heavy metals such as lead (Pb), cadmium (Cd), chromium (Cr) and aluminium (Al) found in cigarette smoke can cause heavy metal toxicity, which includes the inhibition of antioxidant pathways via the depletion of antioxidant elements such as glutathione (GSH) and inhibition of antioxidant enzymes resulting in improper eradication of reactive oxygen species (ROS) which leads to cellular damage. A diet which is low in endogenous antioxidants such as polyphenols exacerbates this toxic effect. Supplementation with dietary antioxidants, if positive would be a cost effective, relatively simple method in helping to decrease the toxic effects of heavy metal exposure. Therefore the aim of this study was twofold, namely to determine the toxicity of metals commonly found in cigarette smoke using an erythrocyte ex vivo model and then to determine if antioxidants that are bioavailable can reduce toxicity. The methods used by this study are haemolysis assay, Fenton reaction, dichlorodihydrofluorescein diacetate (DCFH-DA) assay, Trolox equivalent antioxidant capacity (TEAC) assay, total flavonoid content (TFC) assay, Glutathione (GSH) assay and Scanning Electron Microscopy (SEM). Pb was found to be the most toxic metal, causing 50% haemolysis (H50%) at a concentration of 16.00mM and toxicity was associated with echinocyte, type III formation. Pb was a poor catalyst of the Fenton reaction, but exposure of erythrocytes to Pb caused increased ROS formation. Pb did not bind GSH, however in erythrocytes it caused an increase in GSH levels. This implies that the oxidative effect of Pb, is not as a catalyst of the Fenton reaction or due to GSH binding. The observed effects may be due to the ability of Pb to inhibit antioxidant enzyme activity, resulting in an increase in GSH levels and subsequent accumulation of ROS. Catechin, gallic acid and 6-Hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) effectively reduced the oxidative effects of Pb. Catechin and gallic acid did not alter Pb induced increase in erythrocyte GSH levels. Catechin, gallic acid and Trolox bound GSH and reduced the amount of free GSH. Cd induced H50% at a concentration of 33.83mM and the formation of spherocytes. The latter was similar to the effect observed with the oxidant AAPH. Cd catalysed the Fenton reaction and binds GSH, however in erythrocytes Cd did not cause an increase in ROS or alter GSH levels. This implies that in the erythrocyte, Cd induced ROS formation, directly targets the cell membrane causing changes to membrane fluidity and morphology. Antioxidants did cause some inhibition of haemolysis and antioxidants quercetin and ascorbic acid inhibited the Fenton reaction and bound Cd. This metal antioxidant interaction caused a loss in the antioxidant activity of ascorbic acid but enhanced the activity of caffeic acid. Trolox reduced Cd – GSH binding. At a concentration of 47.83mM Cr caused H50% and induced echinocyte type III formation. Cr catalysed the Fenton reaction and bound GSH in a manner similar to Cd. Likewise Cr did not cause an increase in ROS formation but did cause changes in GSH levels, similar to those seen with Pb. The higher Cr concentrations required for haemolysis and echinocyte type III formation implies that Cr may be slightly less toxic than Cd and Pb. Catechin and gallic acid reduced Cr induced haemolysis. In the Fenton reaction, quercetin and ascorbic acid scavenged hydroxyl radicals and this caused a loss in the antioxidant activity of ascorbic acid while enhancing the antioxidant activity of quercetin. Catechin and gallic acid reduced the ability of Cr to bind GSH. Of all the metals investigated Al, was the least toxic, with H50% occurring at 81.26mM and was associated with echinocyte type I formation. Al was a poor catalyst of the Fenton reaction but did bind GSH. In ex vivo erythrocytes, Al did not induce ROS formation or changes in GSH levels. Catechin, gallic acid and Trolox reduced haemolysis. Trolox inhibited Al catalysis of the Fenton reaction. Al had no effect on the antioxidant activity of catechin, gallic acid and Trolox although metal antioxidant interactions enhanced the activity of quercetin and caused a loss in the antioxidant activity of ascorbic acid. Catechin and gallic acid caused an increase in erythrocyte GSH levels which was unaltered when erythrocytes were exposed to only Al. In summary, some antioxidants, especially catechin, gallic acid, Trolox and ascorbic acid prevented metal induced cellular damage. The observed effects may be related to direct radical scavenging, GSH protection against metal binding or may be due to unknown membrane effects especially considering the effect of Trolox. Of concern is the adverse effect of these metals on the bioactivity of ascorbic acid.Dissertation (MSc)--University of Pretoria, 2017.
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Udeozor, Jude Onyeka, and Jude Onyeka Udeozor. "Application of Industrial Wastewater Effluent in Growth of Algae -- Effects of Heavy Metals on the Growth Rate, Fatty Acid and Lipid Content of Chlorella Sorokiniana and Scenedesmus Obliquus." Thesis, The University of Arizona, 2017. http://hdl.handle.net/10150/626388.
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Growing interest in biofuel production from non-fossil fuel sources has resulted in several studies exploring different raw material sources as feedstock, including many algae species, for large-scale production of biofuel. Algae are promising feedstock due to advantages such as its short growth cycle, high biomass production, and lipid content. However, there are still challenges to overcome in order to use algae for commercial biofuel production. One of these challenges is the requirement for a large quantity of water and nutrients needed for growing large quantities of the algae.
This work explores a potential solution to this challenge by studying the possibility of using industrial wastewater to grow algae for biofuel production. However, many industrial wastewaters, including effluents from semiconductor processing plants, are known to contain heavy metals that are toxic to humans and the environment. In this work, the effects of four of such metals ions, As(V), As(III), Ga(III), and In(III) on Chlorella sorokiniana and Scenedesmus obliquus strains were studied. In particular, the heavy metal toxicity on the strains, effects on its growth rate, biomass yield, lipid content and fatty acid methyl esters (FAME) were studied. Also, the effect of controlling pH on growth rate, biomass yield, lipid content, and FAME was studied for Chlorella sorokiniana in the presence of Ga(III).
The results of the study confirmed the toxicity of these metals on both strains. However, Ga(III) and In(III) had the highest effect, while As(V) showed the least toxicity to the strains, with Chlorella sorokiniana withstanding concentrations of As(V) as high as 140mg/L. The heavy metals were slightly more toxic to Scenedesmus obliquus compared to Chlorella sorokiniana. In addition, the heavy metals reduced the growth rate of both strains. High percent changes in growth rate (more than 50%) were seen in cultures containing Ga(III) and In(III). Furthermore, concentration measurements with Inductively Coupled Plasma Optical Emission Spectrometer (ICP) before, during, and at the end of the growth period, showed that Scenedesmus obliquus adsorbed higher amounts of the heavy metals compared to Chlorella sorokiniana. Microalgae biosorption of heavy metals limits its end use, hence making Scenedesmus obliquus a less favorable option for this study, but may be a better choice for wastewater treatment applications.
The effects of the four metals on the lipid content and FAME profile of Chlorella sorokiniana were studied. The result showed an increase in Chlorella sorokiniana lipid content in the presence of In(III), but a decrease in the presence of As(V) and As(III). The heavy metals had effects on the strain’s FAME compositions. The fatty acid composition included C16:0, C16:1, C16:2, C16:3, C18:0, C18:1, ω-6, C18:2, ω-6, and C18:3, ω-3 accounting for more than 97% of the total FAME composition. Furthermore, controlling the pH of the culture in the presence of Ga(III) at 6.5 led to higher adsorption of the heavy metal, increase in lipid content, but no significant change in FAME composition.
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Simpson, Julia Marie. "Effects of heavy metal contamination on burial rates of Austrovenus stutchburyi implications for sediment transport /." The University of Waikato, 2009. http://hdl.handle.net/10289/2766.
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Urbanisation in coastal catchments has significantly increased not only the input of terrestrial sediment to the marine environment but also the input of contaminants. In Tamaki Estuary, Auckland, heavy metals have accumulated in the upper estuarine muddy sediments and metal contamination has been detected on downstream intertidal sandflats. Sub-lethal levels of heavy metal contamination may affect the growth and behaviour of benthic organisms, which in turn may influence key ecosystem processes and productivity. The aim of this study was to examine whether the burial rate of an ecologically important bivalve species (Austrovenus stutchburyi) differed between a contaminated and a lesser-contaminated site and whether burial rates were affected by density. A secondary aim was to determine whether the burial of Austrovenus affected sediment transport and consequently if this was affected by density. This study demonstrated no consistent difference in burial time between source populations (sites). This was explained by a lack of measured difference in the condition index and heavy metal tissue loading of Austrovenus used throughout this study. The present range of contamination measured in Tamaki Estuary, Auckland, did not have negative biological consequences on the key ecosystem engineer, Austrovenus stutchburyi. Contamination levels in Tamaki Estuary may not be high enough to cause major physiological or behaviour changes to infaunal organisms, such as Austrovenus. Sediment erodability was not significantly correlated with any measured environmental and biotic factors. Austrovenus density was the only predictor variable that could be used to explain any variation in sediment erodability. There was no significant density effects observed between the amounts of sediment eroded for densities gt; 150 ind. m-2. There was a significant difference between sediment void of Austrovenus (0 ind. m-2; smooth, flat undisturbed sediment surface) and sediment containing Austrovenus (gt;150ind. m-2; physical structure on/in the sediment surface, increase in bed roughness). These results indicate that there is little or no effect of Austrovenus on the critical erosion threshold, suggesting that in the absence or presence of Austrovenus the current required to erode 10 g m-2 of sediment would remain somewhere between 28.5 and 30.5 cm s-1. This study found that there was considerable variation in the burial rate of individuals and the greatest variation was recorded in the lowest density treatments (150 ind. m-2), which corresponded to the same density that had the greatest variation in sediment erodability. Further investigations are needed to gain a better understanding into the important roles (the importance of the various feedbacks and limitations and interrelationships) that Austrovenus play in the soft-sediment ecosystem, as losses of this species are likely to have large-scale impacts on the wider soft-sediment communities and ecosystem functioning.
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Rind, Baloch Ali Hassan. "Studies on the effects of salinity and heavy metals on the sporophytic & gametophytic generations of Arabidopsis thaliana (L.) heynh." Thesis, Durham University, 1994. http://etheses.dur.ac.uk/5110/.
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The aim of this research was to study the effects of Salinity & Heavy Metals on the Sporophyte & Gametophyte generations of Arabidopsis thaliana. After developing a pollen germinating protocol, some basic experiments were conducted to determine the effects on chemical & physical parameters on pollen germination & pollen tube growth. Additions of heavy metals & high concentrations of buffer (Tris-HCI) in pollen germinating medium (PGM), inhibited pollen germination (PG) & pollen tube length (PTL), while pH range (7.0-9.0) had little effect. The idea of 2-fold effect (nutritional & osmotic) of sucrose was supported in results. In vivo pollen growth was much greater than in vitro & genotypic differences occurred among the mutants for PG & PTL. Comparing the pollen nutritional requirements for PG & PTL between Cicer arietinum & A. thaliana, it was noted that the pollen of the former had a greater requirement for H(_3)BO(_3) & Ca(N0(_3))(_2) than latter. The range of temperatures (0 C-35 C) studied, indicated that the most favourable temperature for PG was 20 C & for PTL 25 C , while extreme temperatures (0 C, 35 C) were harmful to A. thaliana pollen. 20 C was found to be optimum temperature for PG & PTL of C. arietinum. Correlation between pollen tube growth rates (PTGRs) and sporophytic traits of Fls showed a generally strong positive correlation with most of sporophytic traits, but a very loose to negative correlation for earliness parameters. Recording the impacts of salinity, parallel effects were found for the sporophytic & gametophytic generations of the plant, as reported by earlier workers. The results also indicated that it is possible to develop a pollen plant salinity index (PPSI) for plant species under specific plant growing conditions. It was also observed that salinity stress during pollen gametogenesis preconditioned pollen to high salinity levels, resulting in higher PG & PTL than in pollen raised under non-saline conditions. Similarly, the fruit-setting, seed-setting & seed-filling were relatively less affected by saline-stress, in progeny when pollen and pistilate plants were grown under similar saline regimes. Anatomical studies showed that salinity induced changes in the epidermis, cortex, pericycle, xylem, pith & cross sectional diameter of vascular bundle (CSDVB) in stem, leaf & root tissues. Lower reductions for the fruit-setting, seed-setting & seed-filling were recorded in response to the high heavy metal concentrations in progeny when pollen and pistilate plants were raised under similar heavy metal regimes. It was apparent that pollen become conditioned to a stress environment during its development in the anthers of stressed plants, & this preconditioning allowed its pollen tubes to grow more successfully in the styles of the female parents growing in a similarly stressed environment, where the pistil may have accumulated higher levels of heavy metals. Heavy metals induced changes in stem shape, epidermis, cortex, vascular bundles & chloroplasts in stems. The metals induced changes in the leaf thickness, epidermis, palisade cell size, spongy mesophyll area, size of intercellular spaces & chloroplasts in the leaf, causing disruption of cortical layers, lignification of pericycle & phloem, damage to the endodermis and increase in xylem cell size & stele diameter in roots.
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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.
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Hallman, Tyler Andrew. "RESPONSES OF HYLA CHRYSOSCELIS TO SUBLETHAL METAL MIXTURES UNDER INCREASING TEMPERATURES: IMPLICATIONS FOR THE EFFECTS OF CLIMATE CHANGE ON AMPHIBIANS." OpenSIUC, 2012. https://opensiuc.lib.siu.edu/theses/934.
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Amphibian populations are rapidly declining worldwide. Although individual factors may have large local influences, worldwide declines are attributed to interacting global stressors including rising temperatures and environmental pollutants. Globally, water temperatures closely track rising air temperatures and increase the metabolic rates of aquatic ectotherms, changing the rates of uptake, biotransformation, and excretion of contaminants, such as metals. To test how interactions of multiple, chronic stressors affect amphibian growth, I exposed Cope's gray treefrogs (Hyla chrysoscelis) in an outdoor mesocosm facility to three temperature regimes (ambient, ambient +1.5 oC, ambient +2.5 oC) in filtered lake water amended with mixtures of cadmium, copper, and lead ranging from 3.7 to 26.7 risk quotients (relative to the chronic concentration criteria protective of freshwater organisms). Temperature shifts and sublethal metals concentrations significantly affected the energetics of tadpoles as assessed by non-parametric and parametric analyses. Regression analyses indicated no significant relationship between temperature and time to forelimb emergence at the three lowest metals concentrations, but the relationship was parabolic at the three highest concentrations, indicating a differential effect of temperature across a gradient of water quality. The concept that tadpoles increase developmental rates to escape unfavorable aquatic conditions was supported at each temperature by shortened time to forelimb emergence (Gosner Stage 42) at the second highest metals concentration. This response, however, was overwhelmed by the energetic costs associated with the highest concentration and the highest temperature. Moreover, these parabolic relationships match predictions based on species specific thermal windows and pejus temperatures. My findings indicate that global warming may affect contaminated waters to a greater extent than pristine aquatic ecosystems, and that the primary effect may be diminished pejus and critical thermal maximum temperatures, and a narrowing of the species' thermal window.
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Wong, Nga Cheung. "Effects of algae (Isochrysis galbana) and humic acids on copper toxicity to polychaete (Hydroides elegans) larvae." HKBU Institutional Repository, 2005. http://repository.hkbu.edu.hk/etd_ra/665.
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Wu, Chuan. "Effects of radial oxygen loss (ROL) on arsenic tolerance, uptake and distribution by rice (Oryza sativa L.)." HKBU Institutional Repository, 2011. http://repository.hkbu.edu.hk/etd_ra/1246.
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Lin, Yu-Chen, and 林語蓁. "Morphological and Physiological Effects of Heavy Metals on Thraustochytrids Isolated from Fallen Mangrove Leaves in Taiwan." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/41555724798456627018.
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碩士國立臺灣海洋大學
海洋生物研究所
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Abstract The objectives of this thesis are: (1) to investigate the growth and morphological effects of increasing heavy metal stress on three strains of thraustochytrids isolated from fallen mangrove leaves collected in Kaohsiung Erjen river estuary, Tainan Yan-Tian ecological park mangrove and Miaoli Chu-Nan mangrove, caused by three heavy metals commonly exist in Taiwan’s metal-polluted river: copper, zinc and lead, and (2) to trace the fate of the selected heavy metal ions using atomic absorption spectrophotometer (AAS). Experiment on growth indicated that EC60 of Schizochytrium sp. EJ56 and Schizochytrium sp.CN75 was 64 ppm Zn2+, while EC60 of Schizochytrium sp.YT90 and Schizochytrium sp.CN75 was 128 ppm Cu2+ and EC60 of all strains was 512 ppm Pb2+. These results suggest that the toxicity of heavy metals on growth of thraustochytrids is in the order: Zn2+> Cu2+> Pb2+. Schizochytrium sp.CN75 was most tolerant to Cu2+ and Zn2+ while Schizochytrium sp.YT90 grew best in the presence of lead. Among all the isolates tested, Schizochytrium sp.CN75 was the most tolerant to the selected heavy metal ions. These suggest that thraustochytrids isolated from the river near the industry park (Schizochytrium sp.EJ56) may be more sensitive when facing to heavy metal stress. Observation of morphological changes on thraustochytrids under elevated heavy metal pressures under SEM (scanning electron microscope), heavy metals led to the formation of holes on cell wall, shrinkadge of cells and deformation of cell. At highest metal concentrations, cell lysis was observed and intracellular content leaked out. Under differential interference contrast microscope, perfectly round cells were observed in control and deformed cells were seen at the highest metal concentration. We detected heavy metal reduction by treating quantitative concentrations of heavy metals before and after thraustochytrids growing. The appearance of copper, zinc and lead reduction indicated that thraustochytrids can reduce in vitro heavy metals during their growth and the reduction rate was: Pb2+ > Zn2+ > Cu2+. The most significant reduction range were between 1 ppm and 256 ppm. The mechanism of heavy metal reduction by thraustochytrids remains unknow. We look forward follow-up studies to find out if the missing metals were adsorpted or absorpted by thraustochytrids, or both pathways contribute to the results. The results in the current study clearly shown that in the presence of high concentrations of heavy metal ions, growth of thraustochytrids would be retarded, eventually causing death. More effort should be done on the effects of heavy metal ions on the ecology of thraustochytrids, an important decomposer in marine environment.