No description available.

No description available.

A pollution survey was done in Milnerton industrial area along three transects, the coastal road, the R27 road, and the N7 road. In this project lichens were used as pollution monitors and their availability, abundance and percentage cover were used to estimate the level of pollution. Lichen specimens were collected from St. James, which is far from the pollution source and put in the vicinity of the Caltex oil refinery for four month after which they were analysed for their fluorescence and chlorophyll content. In all transects, lichen species richness and percentage cover increased with distance from the oil refinery, suggesting that indeed lichens are sensitive to pollution and are therefore good air pollution bio-monitors. The fruticose growth forms especially Teloschistes and Usnea were shown in this study to be the most sensitive to pollution because none of them was recorded close to the oil refinery. Photosynthetic pigment analyses revealed that Parmelia and Xanthoria are affected differently by pollution. Parmelia showed chlorophyll a and b injury under high pollution conditions while Xanthoria showed high carotenoid injury. The results of this study indicate that the atmosphere in the Milnerton industrial area is heavily polluted, with the Caltex oil refinery being the main pollution source.

The use of manure from animal feeding operations (AFOs) as fertilizer on agricultural land may introduce contaminants to aquatic environments that can negatively affect the health of aquatic organisms. This study utilized a landscape-scale regression-based design to assess the effects of AFOs on contaminant concentrations and resident populations of a pleurocerid snail, Leptoxis carinata, in streams within the Shenandoah River watershed (Virginia, USA). Individual characteristics of L. carinata were also evaluated to provide further understanding of observed population characteristics. In streambed sediment and mollusk tissue, concentrations of the trace element arsenic, used as an additive in poultry feed, were not directly related to watershed densities of AFOs. In-stream concentrations of dissolved nutrients and estrogenic compounds, measured as estrogenic activity, were directly related to watershed densities of AFOs. Population sex ratios of L. carinata varied across study sites, from balanced to female-biased, but were not related to concentrations of estrogenic compounds. However, the spatial variation in population sex ratios, coupled with little variation in site-specific sex ratios across seasons and generations, suggest an influence of site-specific environmental conditions. Individual-level studies of L. carinata revealed that there is an eight month lag between hatching and gametogenesis which could allow disruption of sexual differentiation by environmental contaminants, but further study of the effects of specific contaminants on sexual differentiation in this species is needed. Population densities of L. carinata were related to in-stream nutrient concentrations and landscape sources of nutrients, including AFOs, but none of these factors were directly related to the infection prevalence of digenetic trematodes in L. carinata populations. Although trematode infection rates in L. carinata populations do not appear to be viable indicators of the influence of eutrophic conditions on disease incidence in aquatic organisms, the identification of five types of trematodes in L. carinata populations highlights the utility of this snail species for further investigation of transmission dynamics of trematode parasites in lotic systems. / Ph. D.

No / Human biomonitoring studies aim to identify potential exposures to environmental, occupational, or lifestyle toxicants in human populations and are commonly used by public health decision makers to predict disease risk. The Comet assay measures changes in genomic stability and is one of the most reliable biomarkers to indicate early biological effects, and therefore accepted by various governmental regulatory agencies. The appeal of the Comet assay lies in its relative simplicity, rapidity, sensitivity, and economic efficiency. Furthermore, the assay is known for its broad versatility, as it can be applied to virtually any human cell and easily adapted in order to detect particular biomarkers of interest, such as DNA repair capacity or single- and double-strand breaks. In a standard experiment, isolated single cells are first embedded in agarose, and then lysed in high-salt solutions in order to remove all cellular contents except the DNA attached to a nuclear scaffold. Subsequent electrophoresis results in accumulation of undamaged DNA sequences at the proximity of the nuclear scaffold, while damaged sequences migrate towards the anode. When visualized with fluorochromes, these migrated DNA fragments resemble a comet tail and can be quantified for their intensity and shape according to internationally drafted guidelines.

Stormwater retention ponds, constructed primarily for services such as flood control, are abundant in urban landscapes and documented hotspots of aquatic biodiversity. A previous study completed in our lab measured benthic community structure in several stormwater retention ponds in North Central Texas along an urban gradient. Results showed that larval chironomids (Diptera: Chironomidae) were the dominant macroinvertebrates in all of the ponds. It was also determined that differences in pond conditions associated with urban development could only be determined when chironomids were identified to the genus-level. However, collection and identification of chironomid larvae is often time-consuming. The objective of this current study is to evaluate the efficacy of the Chironomidae pupal exuviae technique (CPET) to detect changes in water quality in the same series of urban ponds in North Central Texas over one year. Based on results, CPET is an effective method of analyzing chironomid community response to environmental changes associated with anthropogenic impact. A total of 16,635 pupal exuviae were collected during this study representing 80 chironomid taxa, which included 40 genera across three subfamilies. The chironomid communities differed between ponds in proportion to the intensity of the urban development within their watersheds. Additionally, CPET provided the emergence phenology of a highly diverse chironomid assemblage. Results indicated that urban ponds in North Central Texas can provide refuge for biodiversity in a semi-arid region. As urbanization is projected to increase globally, it is critical to monitor how rapid urban expansion affects biodiversity and freshwater ecosystem conditions.

This study investigated trace essential metals (Cu, Zn and Cr) and non-essential metals (Pb, Cd and Hg) in water, sediment and tissues of water spinach, snake head fish and swamp eel from the Saigon River. Sampling was conducted from January to December 2004 at three sites. Three water and sediment samples, edible parts of twenty water spinach (Ipomea aquatica) samples (leaves and stems), twenty snake head fish (Channa striata) and twenty swamp eels (Monopterus albus) were collected at each site. Water, sediment and biota tissues were analysed for Cu, Zn, Cr, Pb, Cd and Hg following the method of USEPA, AOAC and NFTA. Results showed that Cu, Zn, Cr, Cd and Hg in water from the river was not higher than the maximum permitted level for protection of aquatic life by the national standards while the average Cu concentration in sediment was found to be close to the Effects range- low value and within the slightly polluted range (25- 50 ìg.g-1 dry weight). The results also showed that the river sediment was considered to be contaminated by Zn and Hg in comparison with contaminated sites in Australia and in Thailand. In water spinach, no Cu deficiency was found but Zn was accumulated. No accumulation of Cr, Cd and Hg was revealed but Pb was detectable. The results indicated that snake head and eel may have Cu deficiencies. Pb and Hg were found to be bioaccumulated in the muscle of snake head and eel at some sites on some occasions, but the levels were small. The results showed that metal in sediment liver of snake head muscle of snake head and eel water. The metals in water spinach decreased in the order Zn Cu Cr Pb Cd and Hg; in snake head the metal concentrations decreased in the order Zn Cu Cr PbHgCd and in eel as Zn Cu Cr PbCd and Hg. The ANOVA test showed no significant relationship between metals in the water and sediment and biota. Therefore it was concluded that the metals in the selected biota samples did not reflect the metals in the environment. The essential metals Cu, Zn and Cr were found to decrease at the end of the dry season and then increase at the end of the rainy season. The seasonal variations of metals in the river and biota maybe a result of the change of temperature in the area and the need for essential metals in the reproduction of fish. The results of this study clearly demonstrates that water spinach, snake head fish and swamp eel are not potential bio-indicators for metals in the Saigon River since they did not reflect concentrations of metals in their environment. It was also concluded based on consumption rates that water spinach, snake headfish and eel from the Saigon River do not present any potential health risk to consumers. However, attention should be paid to controlling the load of pollutants entering the river to avoid such risks and future problems.

No description available.

Thesis (doctoral)--Technische Hochschule, Aachen, 2000.

The aims of the work reported in this thesis were threefold; firstly, to investigate the effect of experimental exposure to polycyclic aromatic hydrocarbons (PAHs) on the immune response of dab (<I>Limanda limanda</I>), a sentinel species of flat fish for pollution studies, and rainbow trout (<I>Oncorhynhus mykiss</I>); secondly, to then go into the field to investigate the effects of exposure to PAHs on dab immunity through a major oil spill and thirdly, to increase current knowledge on the cellular immune functions of dab so as to provide better assays for biomonitoring purposes. Chapter 1 of this thesis is a general introduction to immunotoxicology, subspeciality of toxicology, which described brief accounts for both immunology and toxicology. Some brief accounts for the use of fish (lower vertebrates) in a pollution monitoring programme and the toxicology aspects of polycyclic aromatic hydrocarbons, were also given. In chapter 2, a laboratory exposure of animals to oil-contaminated sediment was established where four doses of diesel oil-based drilling mud used, i.e. 4, 8 (seen 500m from oil exploration platforms in the North Sea), 12 and 16% (w/w), with two exposure times employed, i.e. 2 and 4 weeks. Haematocrits and lymphocyte numbers tend to increase with low diesel oil doses, whereas high doses (particularly with longer exposure) gave significantly decreased values. Serum lysozyme levels were decreased, but serum bactericidal and anti-protease activities tended to increase following exposure. Kidney phagocyte respiratory burst and neutrophil migration activity also showed a trend to lower levels relative to control fish, whereas the number of antibody-secreting cells were increased with high drilling mud concentration. Lastly, there was a dose-dependent hepatomegaly. In chapter 3, rainbow trout were injected intra-peritoneally with an extract obtained from diesel oil-based drilling mud. Fish were exposed to different doses of extracts (made up to 2.4 mL/kg with olive oil), i.e. 0, 0.6, 1.2 and 2.4 mL/kg body weight (B.W.), for 6 weeks in the dose effect experiment.