Bioavailability of trace metals in urban contaminated soils was investigated to relate chemical extraction efficiencies with biological effects. / Results from a Collembola reproduction bioassay showed minimal toxicity suggesting limited bioavailability. Chemical extractions were carried out on these urban soils. The sodium acetate extraction was the best predictor of the biological effects of Cd while the biological effects of Zn were best explained by a water extraction. / An earthworm uptake bioassay was done to quantify the bioavailable fractions. Cadmium, Cu, Pb and Zn accumulated in Lumbricus terrestris L. The sodium acetate extraction was the best predictor of Cd uptake while calcium chloride extraction best predicted Zn uptake by earthworms. / Treatments were made to urban soils to immobilize the metals and reduce their bioavailability. The metal concentrations were so low in the soils that the effects of the treatments could not be measured. / Collembola and earthworms are good indicators of trace metal bioavailability and should be included in the evaluation of contaminated soils.

Freshwater ecosystems will likely become sinks for future silver loadings as a result of increased nanosilver (n-Ag) use in industrial and commercial applications. A series of bioassays was performed to assess how n-Ag toxicity may be influenced by abiotic factors associated with natural freshwater ecosystems. Additionally, these bioassays provide insight into how environmentally relevant concentrations of n-Ag may sublethaly affect the freshwater benthic gastropod, Physa acuta, that plays pivotal roles in maintaining the structure and function of freshwater ecosystems. In sediment with no benthic organic carbon (BOC), gastropod vital rates decreased in treatments containing any n-Ag, gastropods in sediment with relatively low BOC appeared to trade off growth for reproduction at high n-Ag treatments, while gastropod vital rates in high BOC sediment remained unaffected at all nanosilver treatments. Sediment type may abate nanosilver toxicity as a result of organic carbon content. Effects of n-Ag on gastropod vital rates were not dependant on pH, suggesting aqueous pH does not directly influence n-Ag toxicity. Nanosilver (0.2 μg/L) stressed gastropods, altering their growth and reproduction tradeoff dynamics. Nanosilver concentrations modeled to exist in natural freshwaters, disrupted gastropod ability to detect and respond to a natural predator, while greater n-Ag concentrations stimulated gastropods to exhibit contaminant avoidance behavior and thereby attempted to flee their habitat. This study provides direction in understanding how adverse n-Ag effects may be influenced by abiotic parameters, while assessing sublethal effects of n-Ag on freshwater gastropods that are likely to occur in natural freshwater ecosystems, given current estimates of environmental n-Ag concentrations. / Department of Biology

Thesis (MSc Food Sc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Many South African farmers are forced to use water from nearby rivers for crop irrigation, since it is the most affordable and sometimes only source of water available to them. During this research project, a baseline study was performed on a farm irrigating fresh produce with water obtained from the Eerste River. The baseline study was done over a five month period, at six preselected sampling points, to determine the microbial and physico-chemical parameters of the water so a baseline could be established to compare the results to when the ultraviolet (UV) apparatus was installed (February 2013). Aerobic colony count (ACC), total coliforms (TC) and Escherichia coli (E. coli) were tested for during the microbiological study, while the physico-chemical analysis comprised of temperature, pH, conductivity, chemical oxygen demand (COD), alkalinity and total soluble solids (TSS). The UV treatment study was also performed over a five month timeline, at eight different sampling points (original six sampling points, with additional sampling points before and after UV). The same microbiological tests were performed during the UV treatment study, but turbidity and percentage ultraviolet transmittance (% UVT) were performed additionally during physico-chemical analysis. During the baseline study ACC, TC and E. coli counts as high as 9 600 cfu.mL-1, 13 799 MPN.100 mL-1 and 2 098 MPN.100 mL-1 were isolated at the river (Sampling Point 1), respectively. While performing the UV treatment study ACC, TC and E. coli counts as high as 142 000 cfu.mL-1, 241 960 MPN.100 mL-1 and 6 867 MPN.100 mL-1 were isolated at the river, respectively. As a result it was concluded that the Eerste River was mostly unsuitable for irrigation of fresh produce that are consumed raw. The higher counts in the river, during the UV treatment study might be attributed to the increase in rainfall that occurred in the sampling months (March to July 2013). The counts as measured at the point of irrigation are considered of greater importance, since the counts present in the river might still decrease to below the guideline levels after passing through sand filters and the addition of hydrogen peroxide (current mode of treatment) or after passing through the UV in the UV treatment study. The ACC, TC and E. coli counts during the baseline study were as high as 8 800 cfu.mL-1, 24 196 MPN.100 mL-1 and 85 MPN.100 mL-1 at the point of irrigation (Sampling Point 6), respectively. After hydrogen peroxide addition average logreductions ranging between 0.65 and 1.13 were seen, but reduction was never constant. The counts at the point of irrigation remained more or less constant compared to the river due to contamination that occurred at the sand filters, making the water unsuitable for irrigation of fresh produce in terms of ACC and TC counts. In the UV treatment study ACC, TC and E. coli counts were as high as 35 000 cfu.mL-1, 10 462 MPN.100 mL-1 and 63 MPN.100 mL-1 at the point of irrigation (Sampling Point 8), respectively. Average log-reductions in the range of 0.90 to 1.25 were achieved, but it was inconsistent. After treatment with chlorine and re-sanding of the sand filters, no further contamination occurred and counts decreased to below guideline limits, making the water safe for irrigational use in terms of all of the microbiological parameters. Not only is UV treatment more effective in reducing microbiological counts than H2O2, it is also relatively less expensive in the long term. Hydrogen peroxide treatment of water amounts to a very high capital expense every month, whereas UV may seem expensive when starting up, but the monthly operating cost thereafter is marginally less than for H2O2. It is of great importance to farmers to find a treatment that would reduce the counts in the river water to below the guideline limits required for safe irrigation since pathogens can be carried over from water onto fresh produce, resulting in an increase in produce-associated foodborne outbreaks and loss of consumer trust. / AFRIKAANSE OPSOMMING: Menigte Suid-Afrikaners is afhanklik van nabygeleë riviere om hulle oeste te besproei aangesien dit meestal die mees bekostigbare en soms enigste bron tot hul beskikking is. Tydens hierdie projek is ‘n grondslag sowel as ‘n UV behandelingsmetode studie uitgevoer op ‘n plaas wat vars vrugte en groente besproei met water water wat hul vanuit die Eersterivier verkry. Die grondslagstudie is oor ‘n tydperk van vyf maande uitgevoer by ses voorafgekose punte. Dit is gedoen om die mikrobiologiese sowel as chemiese parameters van die water te bepaal sodat ‘n grondslag beskikbaar kon wees om met resultate te vergelyk wat met behulp van die ultravioletmasjien verkry is (in Februarie 2013 geïnstalleer). Tydens die mikrobiologiese studie is daar vir aerobiese koliform tellings (ACC), totale koliforme (TC) en Escherichia coli (E. coli) getoets. Tydens die chemiese analise is temperatuur, pH, konduktiwiteit, chemiese suurstof benodiging, alkaliniteit en totale oplosbaie vastestowwe in die water getoets. Die UV behandelingsmetode studie is ook oor ‘n tydperk van vyf maande uitgevoer, met twee addisionale toetspunte by. Presies dieselfde mikrobiologiese analises as wat tydens die grondslag studie uitgevoer is, is tydens die UV behandelingsmetode studie uitgevoer, maar vir die chemiese analise het turbiditeit en persentasie ultraviolet transmissie van die water bygekom. Gedurende die grondslag studie was ACC, TC and E. coli tellings so hoog as 9 600 cfu.mL-1, 13 799 MPN.100 mL-1 en 2 098 MPN.100 mL-1 onderskeidelik uit die rivier geïsoleer (Punt 1). Tydens die UV behandelingsmetode studie was ACC, TC en E. coli tellings so hoog as 142 000 cfu.mL-1, 241 960 MPN.100 mL-1 en 6 867 MPN.100 mL-1 onderskeidelik by die rivier geïsoleer. Gevolglik is daar afgelei dat die Eersterivier se water meestal ongeskik is om te gebruik vir die besproeiing van vars groente en vrugte wat rou geëet word sonder dat enige verdere behandeling plaasvind. Die hoër tellings wat tydens die UV behandelingsmetode in die rivier sigbaar was kan hoofsaaklik toegeskryf word aan die toename in reënval in daardie tyd (Maart tot Julie 2013). Tellings soos gemeet by die punt van besproeiing is wel van groter belang as die wat aangeteken is by die rivier; aangesien die tellings wat in die rivier aangeteken is steeds kan afneem tot onder aanvaarbare hoeveelhede soos in die standaarde uiteengesit, want die water moet steeds deur sandfilters beweeg en word ook huidiglik deur waterstofperoksied behandel tydens die die grondslagstudie of beweeg deur die UV apparaat in die UV behandelingsmetode studie. Die ACC, TC en E. coli tellings soos gemeet by die besproeiingspunt (Punt 6) was so hoog as 8 800 cfu.mL-1, 24 196 MPN.100 mL-1 en 85 MPN.100 mL-1, onderskeidelik. Na waterstofperoksied byvoeging was die gemiddelde log-reduksies sigbaar, tussen 065 en 1.13, maar afnames was nooit konstant nie. Die tellings by die punt van besproeiing het ongeveer konstant gebly in vergelyking met die tellings wat by die rivier aangeteken is; moontlik as gevolg van die hoë kontaminasie vlakke in die sandfilters. Kontaminasie van sandfilters het veroorsaak dat die water ongeskik was vir die gebruik van besproeiing van vars groente as gevolg van die hoë ACC en TC vlakke. Tydens die UV behandelingsmetode studie is ACC, TC en E. coli tellings so hoog as 35 000 cfu.mL-1, 10 462 MPN.100 mL-1 en 63 MPN.100 mL-1, onderskeidelik aangeteken (Punt 8). Gemiddelde log-reduksies tussen 0.90 tot 1.25 was verkry, maar behandeling en afnames in tellings was nie konstant nie. Nadat die sandfilters met chloor behandel is en die sand daarin vervang is, het geen verdere kontaminasie by die punt voorgekom nie. Nadat al die voorafgenoemde behandelings afgehandel is, het die tellings tot laer as die van die standaarde gedaal en dus was die water nou veilig om te gebruik vir besproeiingsdoeleindes in terme van die mikrobiologiese parameters. Die UV behandelingsmetode is nie net meer effektief in die verlaging van mikrobiologiesese tellings as waterstofperoksied nie, dis ook heelwat goedkoper in die langtermyn. Waterstofperoksied behandeling van water lei tot ‘n baie hoë kapitale onkoste per maand, terwyl UV baie duur mag voorkom in die beginfase, maar die maandelikse kostes is aansienlik laer as die van waterstofperoksied en maak sodoende op daarvoor. Dit is van uiterste belang vir boere om ‘n water behandelingsmetode te vind wat die hoë tellings in die rivier sal afbring tot laer as Suid-Afrikaanse en Kanadese riglyne; aangesien patogene oorgedra kan word van vars vrugte en groente. Laasgenoemde kan tot ‘n drastiese toename in vars voedsel geassosieerde siektes en gevolglik ‘n afname in die vertroue wat ‘n kliënt in ‘n produk plaas, lei.

Ph.D. (Zoology) / The present study deals with the effects of metal-polluted aquatic habitats at five different localities on the Witwatersrand and the Orange Free State on the concentrations of lead, nickel, copper and cadmium in the organs and tissues of the Redknobbed Coot, Fulica cristata, the Sacred Ibis, Threskiornis aethiopicus, and the Reed Cormorant, Phalacrocorax africanus. The physical and chemical conditions of the water and the sediments which prevailed during the period of survey at the various sampling sites suggest that concentrations of parameters such as phosphates, nickel and lead in a number of cases exceeded the limits laid down by Kempster et at. (1980) for acceptable river water quality standards in South Africa. The major sources of pollution responsible for these conditions can primarily be related to sewage, mine and industrial effluents (urban) as well as agricultural practices (rural), respectively. Mining activities were largely responsible for the acidification and miniralization as well as metal pollution of the water and sediments, especially so at the Marievale Bird Sanctuary in the Blesbokspruit catchment area. However, automobiles are suspected to contribute much towards the lead concentrations in the water and sediments at all the sampling sites. Levels of cadmium were generally low and may be the only one of the four metals analysed which truly reflected unpolluted, environmental conditions for this metal in the water and sediments of all the sampling sites. The nutrient loads which suggest mild to moderate eutrophication of the water at all the localities can largely be attributed to sewage effiuents and surface runoff waters from the surrounding townships on the Witwatersrand as well as from inorganic fertilizers from farm lands in the vicinity of the Steynsrus and Senekal farm dams in the Orange Free State. These conditions resulted in the overall increase in primary and secondary production of the affected waters which also coincided with the development of submerged and floating water weeds such as Potamogeton pectinatus and Azolla filiculoides, respectively. The herbivorous Redknobbed Coot and to a lesser extent the piscivorous Reed Cormorant, benefitted directly or indirectly from these conditions. Data obtained during the investigation present a complex situation in terms of the environment and the biological availability of the four metals under discussion. A number of factors in both the abiotic and biotic components may have had an effect on fluctuations in metal concentrations. These may have acted individually and/or synergistically, making the interpretation of the data difficult. Cadmium occurred in the lowest concentrations of all four metals in all four the organs and tissues during all four seasons of investigation. In the case of the rest of the metals as well as the organs and tissues no specific, clear seasonal trend or sequence in the concentrations of the metals was discernible. Copper in the kidney and liver and lead in the bone and blood tissues had the highest mean concentrations over the four seasons of investigation. As far as the winter and summer seasonal tendencies are concerned, statistically significant differences occurred in the concentrations of some metals in specific organs and tissues between the winter and summer seasons, respectively. However, values recorded were not necessarily higher during a particular season. Lead (liver) and cadmium (kidney) concentrations were found to be significantly higher in winter 1991 whilst cadmium and copper (both in the blood) were significantly lower during this same season, compared to winter 1992. Concentrations of nickel did not differ significantly between organs and tissues such as the liver and blood for particular seasons. It was only nickel in the kidney and cadmium in the bone tissue which reflected definite seasonal trends for the four successive seasons of investigation.

M.Sc. (Zoology) / The construction of the Pongolapoort Dam in 1974 has altered conditions downstream of the Phongolo River in terms of hydrology, geomorphology, water quality, and ecosystem services. Activities along the Phongolo River permit anthropogenic compounds such as pesticides used in disease control to enter the aquatic environment. This alteration of natural environmental conditions creates a need for a monitoring programme. This study aims to assess the use of Hydrocynus vittatus as an indicator organism of pollution in the Nyamithi Pan and Phongolo River. Water and sediment samples were analysed for a variety of metal elements. The physical characteristics of water samples were determined using a WTW Multi 340i multimeter. Nutrients in water were analysed using a Merck Spectroquant™ Pharo 100 Spectrophotometer. Sediment analysis was based on the standard protocols of the United States Environmental Protection Agency (2001). Physiological stress responses in Hydrocynus vittatus were determined using acetylcholine esterase, catalase, cellular energy allocation, 7-ethoxyresorufin-O-deethylase, malondialdehyde, metallothionein, superoxide dismutase, and protein carbonyls. Employing standard techniques H. vittatus was analysed for metals and organics using ICP-MS, ICP-GS and ICP-OES. Results for biological responses and bioaccumulation show significant differences between sites related to the environmental concentrations of elements. Organisms in the Phongolo River have elevated concentrations of DDT and the metabolites indicating recent exposure. Organisms from the Phongolo River are seen to be responding based on up or down regulated concentrations of biological markers. In particular, concentrations of CAT, MDA and PC are elevated in the Phongolo population with decreased AChE responses indicating toxicant exposure. Data accumulated in this study will contribute to the establishment of baseline chemical, physical and biological knowledge of the effects of contamination in South African waters.

Proteomic techniques were used to analyze the protein profile of earthworm, Lumbricus terrestris, coelomic fluid collected by either whole body dissection method or the coelomic cavity puncture method. Data demonstrated that collection of coelomic fluid using the coelomic cavity puncture method protocol resulted in a 32% reduction, 377 +/- 4.5 vs 253+/- 19.9 (p=0.0007), in the number of individual proteins. It was determined that the coelomic cavity puncture method yielded a "cleaner" preparation, one less contaminated with extraneous proteins from intestinal tissue, gut contents, and body wall materials. This protocol was used in all later studies. The same proteomic techniques were used to evaluate the effects that exposure to Cu (1.0 μg/cm2) as CuSO4 had on the earthworm coelomic fluid profile. Comparison of protein profile from exposed earthworms demonstrated a significant reduction in the number of proteins expressed (184 ± 2.64 vs 253 ±19.9 p=0.0192) when compared to control organisms. Cu exposure also resulted in a modulation of the protein profile with treated earthworms expressing 47 new proteins that were not identified in unexposed worm coelomic fluid. Additionally, 116 proteins found in coelomic fluid collected from normal worms were absent in Cu exposed organisms. Finally, 137 proteins were conserved or found in both control and exposed organisms; however of these proteins, 24 were up-regulated, 105 were down-regulated, and 8 were unchanged as a result of Cu exposure.

Mercury (Hg) is a ubiquitous environmental contaminant, which is capable of global atmospheric transport. As a result, even the most pristine aquatic ecosystems are affected by atmospheric Hg deposition, following which microbial transformation yield organic Hg forms, the most concerning of which is methylmercury (MeHg). Methylmercury is capable of bioaccumulation and biomagnification in food webs, resulting in potentially toxic body burdens due to regular dietary exposure in long-lived organisms at higher trophic levels. It is also a molecular mimic of some endogenous amino acids, providing a route of transfer from mother to offspring via large amino acid transporters. Exposure during neurodevelopment can lead to serious, irreversible neurological dysfunction, associated with a variety of cognitive and motor abnormalities across species. The present studies evaluate the effects of maternally-transferred dietary MeHg, at environmentally relevant concentrations on early life stage fathead minnows (Pimephales promelas). Embryos were collected from adult fatheads exposed to one of three diets with varying concentrations of MeHg for 30 days. Adult reproductive metrics were also monitored over the course of the study, with results indicating no effects on spawning frequency, clutch size, or total egg output. In embryos, Hg concentration was a function of female diet and the duration (number of days) of female exposure. Offspring spawned in tanks administered the low Hg diet displayed altered embryonic movement patterns (hyperactivity), decreased time to hatch, decreased mean larval size, and alterations to several metabolite abundances when compared with controls. Significantly altered metabolites include those associated with cellular energetics, fatty acid metabolism, and polyamine synthesis, indicating current environmental exposure scenarios are sufficient to disrupt important cellular pathways. Dysregulation of the dopaminergic system of embryos is also characterized, and may be a possible mechanism by which hyperactive behaviors are observed in these embryos. Offspring from tanks administered the high Hg diet exhibited delayed hatching, increased mortality, and physiological abnormalities. Brain tissue of exposed adults from the low diet were dissected into regions, and also evaluated for alterations in dopamine cycling. Collectively, these results indicate current exposure scenarios in North American lakes and rivers are sufficient to cause reductions in fitness and survival of early life stage fish. The potential for community structure impacts exists, as sensitive individuals and species become disproportionately affected by chronic, low-level MeHg exposure.

No description available.

No description available.

Thesis (MSc (Botany and Zoology))--University of Stellenbosch, 2007. / The ability of various molluscan species to accumulate toxicants such as cadmium from natural waters in quantities that are many orders of magnitude higher than background levels are well-known. This phenomenon of bioaccumulation might cause certain stress responses in these organisms at the cellular level, which can be measured using biomarkers. A biomarker response test known as the neutral red retention assay was employed in this study to measure responses in four intertidal species. Specimens of Cymbula oculus (Born), Scutellastra longicosta (Lamarck), Cymbula granatina (Linnaeus) and Scutellastra granularis (Linnaeus) were collected at two localities on the coast of False Bay, South Africa. Laboratory exposures in static flow tanks at three different concentrations i.e. 0.8, 1 and 1.2 mg/L of CdCl2 were done respectively for each species over a three day exposure period i.e. each exposure concentration had an exposure period of 24, 48 and 72 hours. After every 24 hour exposure period the lysosomal membrane integrity was determined using the neutral red retention method to establish which species is the most sensitive to Cd. Both control and exposure groups for all species showed a decrease in retention times with an increase in Cd concentration over the exposure period. This decrease was particularly prominent at the highest exposure concentration after 72 hours. At 0.8 and 1.2 mg/L CdCl2 exposures an indirectly proportional relationship between neutral red retention time and heavy metal concentration was prominent in C. oculus, indicating a dose related response. In all species there was a moderate increase in heavy metal concentration over the 72 hour exposure period. EC50 values indicated that S. granularis and C. granatina had a “high” sensitivity to Cd contamination, while C. oculus had “medium” sensitivity and S. longicosta “low” sensitivity to Cd contamination. The sensitivity data obtained from the analysis of the experimental species in this study may contribute to the eventual establishment of a species sensitivity distribution model (SSD).