No description available.

No description available.

No description available.

Risk assessment of environmental exposure to chronic, trace concentrations of contaminants presents an analytical challenge to interpret data in a biologically meaningful way. Biomarkers are compounds that can provide integrated information concerning the effects of contaminants on biochemical processes. The metal-binding protein, metallothionein (MT), is a biomarker of toxic heavy metals, such as cadmium (Cd), since these metals bind to MT in vivo and induce transcription of MT genes with subsequent MT protein synthesis. A high performance liquid chromatography (HPLC)-thermospray microatomization-atomic absorption spectroscopy (AAS) method was developed for detecting Cd proteins from two invertebrate models; freshwater mussels (Pyganodon grandis) from a whole lake ecosystem exposure to Cd (Experimental Lakes Area, Canada), and zebra mussels (Dreissena polymorpha) recently introduced to North America. Methods for coupling gel filtration HPLC to AAS or inductively coupled-mass spectrometry (ICP-MS) were developed to provide sensitive and selective information on metal-binding proteins in freshwater mussel extracts. Sensitive metal detection by these methods necessitated precautions to minimize HPLC column-protein exchange of metals. These interactions were relevant to the determination of low concentrations of mussel MT-like proteins (MLPs) by these metal-specific detection systems. Saturation methods employing Cd as a metallic marker for the quantification of characterized MTs were adapted for freshwater mussels exposed to low environmental Cd concentrations. Characterization of Cd-saturated mussel extracts by HPLC-ICP-MS demonstrated the presence of copper and zinc, metals physiologically bound to MT, in the principal metal-binding fraction of mussel extracts. Experimental results also indicated that mussel MLPs are not as heat-stable as mammalian MT. Zebra mussels were chosen as a bioindicator species for obtaining a standard of freshwater MT biomarker for toxi

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.

M.Sc. (Zoology) / The freshwater indicator fish species, Clarias gariepinus, was used to assess and compare the health status of fish from the Hartbeespoort Dam (HBPD) and the Groot Marico Bosveld Dam (GM) which was used as a reference site. HBPD is known to be polluted and renowned for its extreme eutrophic state. GM receives water from the Marico River and is said to be in an unmodified natural ecological state. Adult Clarias gariepinus were sampled using gill nets; during low-flow (n=17) and high-flow (n=20) seasons from the HBPD, and once from the GM (n = 20). A histology-based fish health assessment was done using a necropsy based health assessment index and a qualitative and semi-quantitative histological assessment on selected target organs namely the gills, liver, kidney and gonads. Focus was also placed on reproductive health aspects by staging the gonads according to their reproductive development and assessing the motility of activated sperm using computer assisted sperm analysis (CASA). Water samples were analyzed for selected physical parameters and for selected metals. The results showed distinct macroscopic differences in the livers and testes comparing the two sites. Fish from HBPD had fatty livers and the macroscopic morphology of the testes showed abnormalities regarding the interstitial tissue, possibly due to the proliferation of connective tissue. The macroscopic abnormalities of the livers were reflected in the histological assessment, which concluded steatosis, vacuolation, hepatocyte nuclear alterations and the presence of large numbers of melanomacrophage centers (MMCs). Of these alterations, only MMCs and intracellular deposits were found in fish from the GM. When comparing the HBPD low-flow (LF) and high-flow (HF) sampling trips, the fish from the low-flow had more alterations present in all organs. While the CASA results showed that the motility, velocity and progression of sperm were lower in fish from the HBPD for all parameters, results from GM showed the ideal trend expected from the moment of sperm activation until degeneration. The velocity and progression were significantly (p value <0.05) different between HBPD samples and fish from the GM. The water quality showed increased concentrations of selenium, as well as the endocrine disrupting chemicals (EDCs) nonylphenol and di-n-butyl phthalate. According to the selected parameters assessed, it seems like the water of the HBPD has increasing detriment upon fish health.

No description available.

No description available.

The goals of this study were to elucidate relationships between food habits and tissue accumulations of heavy metals in Chesapeake Bay waterfowl and to determine effects of chronic cadmium and lead ingestion on energy metabolism in waterfowl. Concentrations of cadmium, lead, copper, and zinc were measured in 774 livers, 266 kidneys, and 271 ulnar bones from 15 species of ducks obtained from the Chesapeake Bay region. Liver and kidney concentrations of cadmium were highest among two carnivorous sea duck species, Clangula hyemalis and Melanitta deglandi. In contrast, lead concentrations in three tissues were generally highest in largely herbivorous species, such as Anas platyrhynchos, Anas rubripes, and Anas strepera. Spent shot may be an important source for tissue burdens of lead in these ducks. No marked trends were observed between food habits and tissue concentrations of copper or zinc. Cadmium and lead concentrations were generally higher in benthic macrophytes than in soft tissues of clams collected from several locations in the Bay. These results suggest that the change that has occurred in the food habits of some Chesapeake Bay ducks, most notably Aythya valisineria to diets composed largely of clams rather than aquatic vegetation probably did not increase ingestion of these elements. In experiments conducted with A. platyrhynchos, chronic ingestion of equal dietary concentrations of cadmium and lead resulted in about 15 times greater accumulation of cadmium than lead in livers and kidneys. However, while ulnar bones accumulated lead, cadmium concentrations in bones remained below detection limits. Cadmium ingestion enhanced renal accumulation of copper and zinc, perhaps due to induction of metallothionein by cadmium. In combination with an imposed food restriction, cadmium ingestion appeared to alter some indices of energy metabolism, such as plasma concentrations of free fatty acids and triiodothyronine, at dietary cadmium levels far below those eliciting similar responses in the absence of a food restriction. Those results suggest the importance of considering interactions with other stressors when examining potential effects of environmental contaminants on wild animals. / Ph. D.

Ph.D. / The current study evaluated a bio-monitoring technique developed in the USA by Adams, Brown and Goede, 1993. This project was sponsored by the Department of Water Affairs and Forestry (DWAF), to enable testing of the Health Assessment Index (HAI) under South African conditions. Testing took place in the Olifants River system, one of the most polluted river systems . in South Africa. Initially two river points were tested using Oreochromis mossambicus (Robinson, 1996), Clarias gariepinus (Marx, 1996) and Labeo rosae (Luus-Powell, 1997). The current study re-tested the HAI at the same two sample sites, namely Mamba and Balule in the Kruger National Park, using 0. mossambicus and C. gariepinus respectively. Two additional sites were tested in the upper catchment area, namely Loskop Dam and Bronkhorstspruit Dam. The current study further enabled the comparison of HAI results collected during drought and flood conditions. Results obtained after deployment of the HAI were corroborated using chemical analysis of water, sediment and biota. Water and sediment analysis was carried out by the Institute for Water Quality Studies using standard techniques. Bio-accumulation of aluminium, copper, iron, lead, manganese, nickel, strontium and zinc was assessed in the gills, liver, skin and muscle tissue of sample fish using standard Atomic Absorption Spectrometry techniques. Modifications made to the original HAI involved the inclusion of variable ranking in the assessment of fish parasites, with endo- and ectoparasites evaluated separately. Testing of this parasite hypothesis lead to the development of a Parasite Index component to the HAI. Assessment of water, sediment and fish tissue determined that the Olifants River system is indeed exposed to macro and heavy metal pollutants, which negatively affect aquatic health. Constituents posing the greatest threat are chlorides, fluorides, phosphates, total dissolved solids, copper and iron concentrations. Testing the HAI and parasite hypothesis using C. gariepinus, provided the most meaningful results. During testing of the parasite hypothesis both endo- and ectoparasite numbers conformed to the suggested idea that higher endoparasite numbers will occur at highly impacted areas, whereby ectoparasite numbers will be low. This was particularly evident in the lower catchment area, whereby comparisons between drought and flood conditions were carried out. Subsequent decreases in water quality directly after the flood were noted using water and sediment analysis. This observation reflects the results gathered using the HAT and during testing of the parasite hypothesis at all four sample sites. During statistical analysis of the HAI, using logistic regression analysis, parasite numbers, more specifically endoparasite numbers, were the most indicative of fish health. Environmental stressors (flood conditions) result in immunological responses observed in fish, and are reflected statistically using the HAI as changes in WBC %. It is suggested that endoparasites and WBC % provide the best overall assessment of fish condition. These variables should thus not be eliminated, in order to streamline the HAI evaluation procedures. Testing of this bio-monitoring technique under South African conditions provided meaningful results. This indicates that the HAI can be used to assess water quality, with existing water monitoring programmes further benefiting from its incorporation.