This research explored fate of organic contaminants in aquatic plant systems through (i) experimental development of relationships to describe sorption, uptake and enzymatic processing of contaminants by plants and inhibition of aquatic plants by contaminants and (ii) incorporation of experimental relationships into a conceptual model which describes contaminant fate in aquatic plant systems. This study focused on interactions of aquatic plants L. minor and M. aquaticum with halogenated phenols. 2,4,5-trichlorophenol (2,4,5-TCP) and 2,4-dichlorophenol (2,4-DCP) are precursors for the highly toxic and heavily applied herbicides 2,4,5-T and 2,4-D and were examined in detail. Chlorophenols are generally resistant to microbial degradation, a property which may limit microbial remediation options as effective alternatives for clean up of contaminated sites. Relationships for fundamental interactions between plants and contaminants that dictate uptake, enzymatic processing and sequestration of contaminants by aquatic plants were established. An assay which quantified production of oxygen by plants was developed to quantify plant metabolic activity and inhibition. Uptake of chlorinated phenols depended on plant activity and aqueous phase concentration of contaminant in the protonated form. Therefore, plant activity, contaminant pKa and media pH were established as critical parameters controlling rate of contaminant uptake. A conceptual model was developed which incorporated plant activity and inhibition into a mathematical description of uptake of organic contaminants by aquatic plants. The conceptual model was parameterized using experimental data delineating effect of plant activity, inhibition and speciation on contaminant uptake and the model was verified using independently gathered data. Experimentation with radio-labeled chlorinated phenols established that contaminants were sequestered internal to plants by plant enzymatic processing. 19F NMR was established as a technique to quantify transformation and conjugation products internal to plants and contaminant assimilation by plants and demonstrated that multiple metabolites containing the parent compound were present and quantifiable internal to plants. Finally, fate of plant-sequestered contaminants in an anaerobic bioassay was examined using Desulfitobacterium sp. strain Viet1. The results of this study address the role of aquatic plants in sequestration of contaminants in surface waters that indicate the potential and limitations of use of aquatic plants in natural and engineered treatment systems.

Human activities such as urbanisation, sewage treatment, industrialisation and agriculture represent major human interference in water resources. The water resources are affected both quantitatively as well as qualitatively by these activities. The impact of human interference in the Mukuvisi River catchment hydrology was studied by determining the concentration values of eight selected physico - chemical and biological parameters. These are pH, temperature, total nitrates, total phosphates, Dissolved Oxygen, Biological Oxygen Demand, lead, copper and Total Faecal Coliform Count. Seven sites were sampled along the river, from up the river in Mukuvisi woodlands up to the point where the river discharges into Lake Chivero. Analysis of the results obtained was undertaken using SPSS (paired sample T test) and descriptive graphs were drawn using Microsoft Excel 2010. Nitrates, phosphates, copper, lead and Total Faecal Coliform Counts were found to be higher than the Zimbabwe National Water Authority (ZINWA) maximum and World Health Organisation, 2011 (WHO) permissible standards from site 3 to site 7. Site 6 recorded the highest concentrations of all the measured parameters, except for pH and Dissolved Oxygen. Mean DO and BOD concentrations were 2.53 mg/l and 40 mg/l respectively at site 6. Mean total nitrates were 17.5 mg/l at site 6 above the ZINWA and WHO threshold of 10 mg/l. Site 6 also recorded a mean total phosphate of 5.9 mg/l which was above the ZINWA and WHO threshold of 0.5 mg/l. Mean TFCC was 992.6 mpn100ml-1 higher than the threshold of nil according to ZINWA and WHO threshold. Site 3 recorded the mean DO and TFCC of 2.4 mg/l and 2.80 mpn100ml-1 respectively. Site 2 had the lowest mean TFCC concentrations of 2.80 mpn100ml-1, which did not differ significantly from the WHO and ZINWA threshold of nil at p<0.05. The quality of water in the river varied from site to site in direct relation to the intensity and type of human activities along the river course. Levels of all the water quality indicators increased after discharge from the Firle sewage treatment plant at site 6 with the exception of temperature and pH. Sewage effluents, agricultural runoff and industrial effluents were found to be responsible for the high nutrient levels and high metal concentrations in the river which in turn reduced DO levels and increased BOD / College of Agriculture and Environmental Sciences / M. Sc. (Environmental Science)

M.Sc. (Aquatic Health) / South Africa’s freshwater ecosystems are under threat due to anthropogenic activities. Recent reports have shown that the Hartbeespoort- (HBPD), Klipvoor- (KD) and Bospoort Dam (BD) impoundments situated in the North-West Province are polluted as a result of mining, industrial and agricultural activities. These impoundments are classified as being in a hypertrophic state. The health status of fish in these impoundments is of concern, and needs to be investigated. For this purpose, Clarias gariepinus and Cyprinus carpio were collected for a histology-based fish health assessment. These two species are present in the selected dams and are some of the preferred fish species for human consumption by the local people. The aim of the study was to determine the health status of these fish species in HPBD, KD and BD using a semi-quantitative histopathological assessment on selected target organs and compare the results to fish from a reference site, the Marico-Bosveld Dam (MBD). Gill nets were used for the collection of specimens. Fish were macroscopically examined, weighed and measured for the calculation of the condition factor. Blood samples were collected for haematocrit, leukocrit and total protein determination. Once sacrificed, a necropsy-based health assessment (HAI) was performed to determine any abnormalities within the visceral cavity. The selected target organs were excised and weighed for the calculation of selected biometric indices. Collected tissue samples were processed using standard histological techniques and the prepared slides were stained using Haematoxylin and Eosin. Macroscopically, a number of fish from polluted sites exhibited liver with fatty change and focal discoloration as well as severe parasites within the visceral cavity. As a result, higher HAI values were recorded in polluted sites compared to the reference site. The haematocrit values varied from normal to below and above the normal range. Leukocrit values were within the normal range except for C. gariepinus from HBPD, which was above the normal range. Total protein values were within the normal range for both species for all sites. The condition factor and hepatosomatic index (HSI) values were within the accepted range except for the HSI of C. gariepinus from MBD. The mean organ index for all study sites fell within class 1 with the exception of the liver index from HBPD, KD and BD which was in class 2. Class 1 (index value <10) is indicative of slight histological alterations while class 2 (index value 10-25) translates to moderate histological alterations. Overall, a higher prevalence of histopathological alterations was noted among fish from polluted sites compared to fish from the reference site. Hence, on the basis of the macroscopic and histopathological results, the fish from the polluted sites were more affected in terms of these parameters compared to fish from the reference site. The results therefore provide valuable information for future bio-monitoring studies in the HBPD, KD and BD impoundments.

With the advent of national storm water regulations, municipalities with populations greater than 100,000 are required to obtain National Pollutant Discharge Elimination System Permits (NPDES) for storm water discharges. In addition to the sampling required for the permit process, the City of Fort Worth contracted with the University of North Texas' Institute of Applied Sciences to conduct acute toxicity testing using Pimephales prcmelas and Ceriodaphnia dubia on storm water samples received from the Dallas/Fort Worth Metroplex. A Toxicity Identification Evaluation (TIE) was performed on four samples that exhibited acute toxicity to C. dubia. High levels of metals as well as diazinon were some of the probable toxicants found.

published_or_final_version / Urban Planning / Master / Master of Science in Urban Planning

published_or_final_version / Urban Planning / Master / Master of Science in Urban Planning

published_or_final_version / Urban Planning / Master / Master of Science in Urban Planning

Environmental toxicants are ubiquitous throughout the environment as a result of human activity. Among these toxicants, environmental estrogens are a category of particular concern due to their environmental prevalence and potency in altering reproductive traits. While many studies have addressed the detrimental effects of environmental estrogens on both aquatic and terrestrial organisms, few have analyzed the potential for these compounds to alter mitochondrial function. Mitochondria are the primary energy-generating system for all eukaryotic life, supporting all aspects of development, metabolism, and growth. Each cell within the body contains many mitochondria which in turn contain multiple copies of their own DNA genome, mitochondrial DNA (mtDNA). Mutations in mtDNA are responsible for a wide range of human diseases such as metabolic syndromes, cancers, and obesity. Among these mitochondrial diseases many are characterized by increased levels of heteroplasmy, multiple mitochondrial DNA haplotypes within an individual. Increased heteroplasmy can alter normal mitochondrial function and influence disease initiation and progression. To date, no studies have investigated the effects of synthetic estrogens on mitochondrial genome stability. Synthetic estrogens have the capacity to bind to estrogen receptors and initiate estrogenic responses through translocation into the mitochondrion. Despite our knowledge about the relationship of heteroplasmy and disease, we still do not have a complete grasp of the mechanisms of heteroplasmic induction. Here we report our analysis of the effects of 17α-ethynylestradiol (EE2) exposure in three studies to investigate its effect on mitochondrial genome stability. Data analysis reveals a statistically significant relationship between EE2 exposure and increased heteroplasmic frequency.

M.Sc. / The increase in industrialisation, mining and agricultural activity along rivers could have a detrimental effect on aquatic environments unless the dangers of pollutants are not taken notice of. Metal ions and industrial effluent have become a source of pollution in the watercourses of South Africa. Pollutants generally have negative effects on the physiology of aquatic biota in polluted waters. The effects of copper and industrial effluent by the exposure of the clawed toad, Xenopus laevis and Tilapia sparrmanii are presented in this study. An experimental static-renewal system with an exposure time of 96 hours was followed at 25±1°C. After copper and effluent exposure, several physiological changes occurred in the two aquatic organisms. The sublethal effects that occurred include changes in hatching, survival, behaviour, growth impairment and developmental limitations. The results of the present study suggest that lethal endpoints can be used as indicators in detecting and evaluating the effects of aquatic pollution, caused by copper and effluent. Individual variation, however, could hamper the conclusions made but the study of aquatic organisms is of practical importance when conducting experimental studies in a laboratory and does not have the same impact as during field studies. Apart from the exposure to sublethal concentrations of copper and effluent, computational derivations of LC50, NOEC values and 95% confidence limits were made. The obtained concentrations were used as assumptions that pollutants should not exceed for the protection of aquatic life. Statistically different differences were found between the chosen derived variables of control and experimental organisms. The advantages of FETAX solution over borehole water can be attributed to the bioavailability of pollutants, which appears to be much less in those solutions. The predicted NOEC values provide some information regarding the concentrations at which no effects will be observed and the Target Water Quality Ranges (TWGR) for water were used to determine if the diluent was correct.

The analysis and modeling of the coastal farfield behavior of inlet discharge plumes is the key to understanding the fate of pollutants discharged into the ocean. These plumes disperse in chaotic and unpredictable patterns. Theoretical models are based on the average conditions and calibrated to the results of tracer studies. Data and models for freshwater discharges in coastal ocean systems are limited because of the lack of adequate tracers. On February, 2007, a tracer study was conducted on the Boynton Inlet, Florida, using sulfur hexafluoride (SF6) tracer. The objective of this study is to provide methods of analysis for the sample data collected during the experiment. The detected tracer concentrated in a bolus that migrated north of the inlet at velocities lower than predicted by the current data. The plume was successfully modeled with a Gaussian plume model, with 90% of the SF6 predictions having less than 4.6 pptr error. / by Joaquin Pire-Schmidt. / Thesis (M.S.C.S.)--Florida Atlantic University, 2009. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.