Thesis (MSc)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: Food demands for the ever-increasing human population is increasing the pressure on the agricultural sector to produce more food. In order to satisfy these demands, farmers are turning to chemical biocides for the control of pest species to produce greater crop yields. All pesticides must be toxic or poisonous to the target species they intend to control. Unfortunately, most pesticides are toxic or poisonous to non-target organisms as well, with detrimental effects on their health. Organic farming was developed to enhance the overall health of the farm's natural soilmicrobe- plant-animal biodiversity. No synthetic fertilisers and/or pesticides are used when farming organically. Life in the soil consists of intricate food webs and interactions between the soil dwelling invertebrates. The soil-organisms are divided into three main groups, viz., Micro-organisms (e.g. protozoa, bacteria and fungi) mesofauna (nematodes, Collembola and Acari) and macro-fauna (e.g. millipedes, isopods, insects, molluscs and earthworms). The invertebrates are very susceptible to chemical contamination by chemical biocides in natural and agro-ecosystems. The soil invertebrate communities are responsible for the decomposition of organic material in soil, thereby remineralising the soil. The decomposition processes start with comminution of the large pieces of organic material by meso- and macro-fauna and ends with the micro-fauna and microbial organisms that complete these processes by returning the nutrients in an inorganic form to the soil. The aim of this study was to investigate whether, and to what extent the soil organisms are influenced by different management practices viz., organic management practices versus conventional management practices. A vineyard on the farm Plaisir de Merle, in Simondium, Western Cape was used for the present study. One half of a one hectare vineyard was managed organically and the other half conventionally. Within each vineyard block six different treatments were performed. Three of the treatments were strictly organic and the other three were strictly conventional. Four replicates of each management treatment were performed. The bait-lamina technique was used to assess the feeding activity of the soil organisms exposed to the different management treatments. In addition to the bait-lamina trials in the vineyard itself, bait-lamina tests were performed in microcosm studies with soil from the organically and conventionally managed vineyard blocks under controlled conditions. In order to assess the impact of the various pesticides that are used in the vineyards in the conventional way, on the soil fauna, standard acute toxicity tests and behavioural tests were performed on Eisenia fetida, the compost worm. The bait-lamina tests in the vineyard revealed that the moisture content of the soil plays an important role in the biological activity of soil fauna. The different management treatments did affect the biological activity of the soil fauna, but seasonal changes also proved to be one of the important factors governing biological processes in the soil. The acute toxicity tests showed that the active ingredients (mancozeb, penconazole and trifloxystrobin) of three of the pesticides that were tested in this study, had negatively affected E. fetida at their recommended application concentrations. The remaining two pesticides' active ingredients (glyphosate and N-acetyl salicylic acid) did not affect the earthworms negatively at the recommended application concentrations. The preference behavioural trials showed that E. fetida could detect and avoid contaminated substrates at the LCso-concentrations of the different pesticides. All the earthworms were influenced positively in the preference behaviour experiments. Because of certain limitations of the bait-lamina technique, it was difficult to formulate conclusions on what happens in the soil. A possible explanation for the differences in feeding activity of soil fauna could be attributed to the migration of the soil fauna to more habitable soil horizons during the dry summer conditions, when most of the pesticides are applied. The ecological relevance of the acute toxicity tests conducted need to be investigated further. It is clear that the acute toxicity tests provided important information that should be considered, but care should be taken and the necessary safety factors be determined and considered when doing risk assessment studies. The results of the preference behaviour studies showed that for certain pesticides E. fetida can be a sensitive bioindicator of acute and/or sub-acute lethal toxicity testing but this might not necessarily be the case for other pesticides. The goal of doing laboratory studies is to gain as much information to make reliable extrapolations to field situations from laboratory data. Laboratory-to-field extrapolations are very complicated because of the physico-chemical composition of soil, the unpredictable way pesticides behave within soil and the reaction of soil organisms to the soil and to the chemical biocides that are used. Further studies need to be done in order to fully understand to what extent the soil fauna were affected by the different management practices applied to the vineyard at Plaisir de Merle. / AFRIKAANSE OPSOMMING: Voedsel aanvraag vir die toenemende menslike bevolking plaas groot druk op die landbou sektor om meer kos te produseer. Om aan die voedsel eise te voldoen, gebruik boere al meer chemiese biosiede om pesspesies te bestry. Alle pestisiede moet toksies of giftig wees vir die teiken organisme waarvoor dit bestem is. Ongelukkig is die meeste pestisiede ook toksies of giftig vir nie-teiken organismes, wat tot nadelige effekte op hul gesonheid kan lei. Organiese boerdery is ontwikkel om die algehele gesondheid van die plaas se natuurlike grond-mikrobe-plant-dier biodiversiteit te bevorder. Geen sintetiese bemestingstowwe en/of pestisiede mag gebruik word wanneer daar organies geboer word nie. Die lewe in die grond bestaan uit ingewikkelde voedselwebbe en interaksies tussen die grondlewende invertebrate. Die grond invertebrate word verdeel in drie hoof groepe, nl. mikro-organismes (bv. Protozoa, bakterieë en fungi) meso fauna (Nematoda, Collembole en Acari) en makrofauna (bv. Millipoda, Isopoda, Insecta, Mollusca en erdwurms). Die Invertebrata is die mees vatbaarste vir chemiese kontaminasie deur chemiese biosiedes in natuurlike en landbou ekosisteme. Die grond invertebraat gemeenskappe is verantwoordelik vir die afbreek van alle organiese materiaal in die grond en dus vir remineralisering van die grond. Die afbreekproses begin by die komminusie van groter stukke organiese materiaal deur die meso- en makrofauna en eindig met die mikrofauna en mikrobes wat die prosesse voltooi deur die nutriente terug te plaas in die vorm van anorganiese produkte in die grond. Die doel van hierdie studie was om te ondersoek of, en tot watter mate, grond organismes geraak word deur verskillende grondbestuurspraktyke, nl. Organiese grondbestuurspraktyke teenoor die konvensionele grondbestuurspraktyke. 'n Wingerd op die plaas Plaisir de Merle, in Simondium, Wes-Kaap, was gebruik vir die huidige studie. Een helfte van 'n een hektaar wingerd is organies bestuur en die ander helfte is op die konvensionele manier bestuur. Op elk van die twee wingerd blokke is ses verskillende behandelings toegepas. Drie van die behandelings was streng organies en die ander drie was streng konvensioneel van aard. Vier replikate van elke behandeling is toegepas op elk van die twee wingerdblokke. Die bait-lamina metode is gebruik om die voedingsaktiwiteit van die grond organismes te asses seer. As toevoeging tot die bait-lamina proewe in die wingerd self, is bait-lamina toetse ook in mikro-kosmosse in die laboratorium gedoen met grond afkomstig vanaf die twee wingerdblokke. Om die impak van die verskillende pestisiede op die grondorganismes te ondersoek, is standaard akute toksisteitstoestse en gedragstoetse uitgevoer met die komposerdwurm, Eisenia fetida. Die bait-lamina resultate in die wingerd het getoon dat die voginhoud van die grond die belangrikste rol speel wat die biologiese aktiwiteit van die grondorganismes beïnvloed. Die verskillende behandelings het die biologiese aktiwiteit van die grond fauna geaffekteer, maar seisoenale veranderings is ook uitgesonder as een van die bepalende faktore wat die biologiese prosesse in die grond stuur. Die akute toksisiteitstoetse het getoon dat die aktiewe bestandeie van drie van die pestisiede (mancozeb, penconazole en trifloxystrobin), E. fetida negatief beïnvloed het teen die aanbeveelde konsentrasies wat toegedien is. Die aktiewe bestandeie van die ander twee pestiede (glyphosate en N-asetiel sallisiel suur) het nie die erdwurms nadelig beïnvloed teen die aanbeveelde konsentrasies wat toegedien is nie. Die gedragsproewe het getoon dat E. fetida die LCso-konsentrasies van al die verskillende pestisiede kan waarneem en vermy. Al die erdwurms is positief beïnvloed in die gedragseksperimente met die verskillende pestisiede. Omdat die bait-laminametode sekere beperkings het, was dit moeilik om tot gevolgtrekkings te kom oor wat presies in die grond gebeur. 'n Moontlike verklaring vir die verskillende voedingsaktiwiteite van die grond fauna kan toegereken word aan die migrasie van die grondorganismes na meer leefbare grondhorisonne gedurende die droë somer toestande, wat toevallig met die spuit van die meeste pestisiede ooreenstem. Die ekologiese relevansie van die akute toksisiteitstoetse wat uitgevoer is, moet meer deeglik ondersoek word. Die belangrikheid van die akute toksisteitstoetse is duidelik en het waardevolle informasie gelewer, maar sorg moet geneem word, en die nodige veiligheids faktore moet bepaal word en in ag geneem word, wanneer riskobepalingstudies gedoen word. Die gedragsproewe het getoon dat vir sekere pestisiede E. fetida 'n sensitiewe bioindikator van akute en/of sub-akute letale toksisiteits toetse kan wees, maar nie noodwendig vir ander pestisiede nie. Die doel van laboratoriumstudies is om so veel as moontlik inligting te versamelom vertroubare ekstrapolasie te kan maak na situasies in die veld vanaf laboratorium data. Laboratorium-na-veld ekstrapolasies is dikwels baie gekompliseerd as gevolg van die fisies-chemiese samestelling van die grond, die onvoorspelbare manier waarop chemiese pestisiede met die grond reageer en die reaksie van die grondorganismes op chemiese biosiede in die grond. Verdere studies moet gedoen word om so deeglik maanlik die mate van die impak wat die verskillende bestuurspraktyke op die grond fauna het, te verstaan op Plaisir de Merle.

Thesis (PhD (Botany and Zoology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The use of organophosphate pesticides is still an integral part of commercial farming activities and these substances have been implicated as a major source of environmental contamination in South Africa. Evidence exists that many non target animals in and around agricultural areas are at risk of being affected due to the mobile nature of pesticides and the intermittent nature of pesticide application. The extent to which non-target animals are affected by exposure to two organophosphates (azinphos-methyl and chlorpyrifos) was investigated through monitoring selected biomarker responses and life cycle effects under laboratory conditions in two selected test species. A representative species from both the aquatic and terrestrial environment was used as these two compartments of the environment are inevitably linked due to the mobility of pesticides from the area of application to surrounding areas. The earthworm Eisenia fetida was used as test organism in the terrestrial environment while the fish Oreochromis mossambicus served as representative of the aquatic environment. Juvenile life stages of both species were subjected to standard acute toxicity tests which showed that for both species, juvenile life stages were more sensitive to both pesticides than adults. It was also illustrated that azinphos-methyl is more toxic than chlorpyrifos to both species. Both test species were also subjected to an intermittent exposure regime in order to assess the effects of repeated pesticide application on biomarker, life-cycle and behaviour responses. The results indicated that for similar exposure regimes, azinphos-methyl was more toxic to E. fetida than chlorpyrifos and detrimentally affected all endpoints investigated. The present study suggests that exposure concentration may have a more pronounced effect in inducing a toxic response than exposure interval, irrespective of the pesticide used. In addition to this, E. fetida was unable to avoid the presence of these pesticides in soil, even at concentrations as high as 50% of the LC50 value, indicating that the presence of pesticides in the soil pose a realistic threat to earthworms and other soil dwelling organisms. Biomarker responses, morphological effects and feeding behaviour was assessed for O. mossambicus and similar to the terrestrial toxicity experiments, there was evidence to suggest that in the case of an intermittent exposure scenario, azinphos-methyl was more hazardous than chlorpyrifos to this species. For the majority of endpoints that were investigated, it appeared that exposure interval played a more important role in inducing an effect than exposure concentration. At a shorter exposure interval, the majority of endpoints showed no difference between higher and lower exposure concentrations, while at a longer exposure interval the effects of exposure concentration became evident. In addition, feeding behaviour was affected by pesticide exposure in a dose-dependent manner. The present study yielded important results that improve the understanding of biological impacts of pesticide pollution on the environment. This can aid in optimising farming practices such as pesticide application not only in terms of eradicating the pest organisms, but also in terms of mitigating the environmental effects associated with large-scale pesticide use, thereby ensuring sustained biodiversity in these areas. / AFRIKAANSE OPSOMMING: Die gebruik van organofosfaat plaagdoders is ‘n integrale deel van kommersiële landbou aktiwiteite maar hierdie middels is ook ‘n prominente bron van omgewingsbesoedeling in Suid-Afrika. Daar is bewys dat verskeie nie-teiken diere in en om landbouareas geaffekteer word weens die nie-statiese aard van plaagdoders in die omgewing, sowel as die herhalende aard van plaagdodertoediening. Die graad waartoe nie-teiken diere geaffekteer word deur die plaagdoders azinphos-metiel en chlorpyrifos is ondersoek deur die monitering van verskeie biomerkerresponse en lewenssiklus-effekte in geselekteerde toetsspesies binne ‘n beheerde laboratoriumomgewing. ‘n Verteenwoordigende spesie van beide die akwatiese en die terrestriële omgewing is gebruik aangesien hierdie twee dele van die omgewing onlosmaaklik verbind is weens die beweging van plaagdoders vanaf die area van toediening na omringende areas. Die erdwurm Eisenia fetida is gekies as toetsorganisme vir die terrestriële omgewing en die varswatervis Oreochromis mossambicus het gedien as verteenwoordigende spesie vir die akwatiese omgewing. Onvolwasse diere van beide spesies is onderwerp aan standaard akute toksisiteitstoetse en daar is gevind dat, vir beide spesies, onvolwasse diere meer sensitief vir die betrokke plaagdoders is as volwasse diere. Dit is ook gevind dat azinphosmetiel giftiger is as chlorpyrifos vir beide spesies. Beide toetsspesies is ook onderwerp aan ‘n chroniese blootstellingsregime om die effek van herhaalde plaagdodertoediening op biomerker-, lewenssiklus- en gedragsresponse te ondersoek. Die resultate van die herhaalde blootstelling het aangedui dat vir soortgelyke blootstellingsregimes, azinphos-metiel giftiger is as chlorpyrifos vir E. fetida en dat beide middels alle eindpunte wat ondersoek is, nadelig affekteer. Die huidige studie toon ook bewyse dat blootstellingskonsentrasie ‘n meer prominente effek as blootstellingsinterval kan hê in die teweegbringing van ‘n toksiese respons. Verder was E. fetida nie in staat om die teenwoordigheid van die plaagdoders in grond te vermy nie, self nie by konsentrasies so hoog as 50% van die LC50 waarde nie. Laasgenoemde resultaat dui dus aan dat die aanwesigheid van plaagdoders in die grondomgewing ‘n realisitese bedreiging inhou vir erdwurms en ander grondorganismes. Soortgelyk aan die terrestriële toksisiteitseksperimente, was daar getuienis vir die verhoogde toksisiteit van azinphos-metiel relatief tot chlorpyrifos vir O. mossambicus. Dit blyk dat blootstellingsinterval ‘n meer prominente rol as blootstellingskonsentrasie speel in die teweegbringing van effekte vir die meerderheid van die eindpunte wat ondersoek is. In die geval van ‘n korter blootstellingsinterval het die meerderheid van eindpunte wat ondersoek is geen verskille getoon tussen ‘n hoër en ‘n laer konsentrasie nie, terwyl met ‘n langer blootstellingsinterval daar ‘n aanduiding was dat blootstellingskonsentrasie ‘n meer prominente rol gespeel het. Verder is gevind dat voedingsgedrag in O. mossambicus geaffekteer is op ‘n konsentrasie verwante manier. Die huidige studie toon resultate wat ‘n belangrike bydrae kan lewer tot die begrip van die biologiese impakte van organofosfaat plaagdoders op die omgewing. Die resultate kan gebruik word vir die optimisering van boerderypraktyke soos plaagdodertoediening, sodat laasgenoemde effektief is vir die beheer van pes-organismes, maar ook die impakte van grootskaalse plaagdodertoediening kan minimaliseer en sodoende die biodiversiteit binne hierdie areas sal beskerm.

An assessment of heavy metal and pesticide pollution was conducted at a commercial airport in Pietermaritzburg, which is the base for a local crop spraying operation, as well as a small-scale aircraft maintenance centre. The study investigated the presence of heavy metals from the aircraft activities (tyre wear, emission and aircraft body attrition) along the edges of the runway. In addition, the study assessed the pollution of the soil in different parts of the airport (areas adjacent to the crop sprayer hangar and maintenance hangars drainage ditch) caused by organic chemicals (pesticides) originating from the washing and maintenance of the crop spraying aircrafts. A total of 37 samples were taken from the top soil (0-15 cm) adjacent to both sides of the runway, approximately 100 meters apart, for heavy metal assessment. Total metal concentrations were determined on a 1:1 HNO3 acid extract analysed using inductively coupled plasma spectroscopy and the results compared with the baseline concentrations of heavy metals in the soils of South Africa. The average levels of the heavy metals in the soils were: Cd - 4.4, Co - 76, Cr - 142, Mn - 6580, Pb - 64 and Zn - 70 mg/kg. The Cd and Co concentrations of all samples and the Pb and Zn concentrations of 86% of the samples were above the South African guidelines for the maximum permissible contents of these metals (2 mg/kg Cd, 20 mg/kg Co, 6.6 mg/kg Pb, 46.5 mg/kg Zn) in soils. In addition, the concentration of Cr was significantly above these guidelines (80 mg/kg Cr ) in 51% of the samples. All the metals, except zinc, were highly correlated with one another indicating the source for these heavy metals is the same. In addition the concentration of these metals was high at sampling points adjacent to the runway where pronounced aircraft tyre wear marks were observed, suggesting that the aircraft activities are the sources of these heavy metals. A total of 13 samples were collected from areas adjacent to the crop sprayer hangar and the drainage ditch (at the maintenance hangars) in order to determine the qualitative presence of organic pollutants. The samples were prepared using soxhlet extraction. Cypermethrin, deltamethrin, azoxystrobin, fusillade and fluazifop-p-butyl as well as fuel oils Jet Al and Avgas were qualitatively determined using GC/MS. Only fusillade and fluazifop-p-butyl were detected, in some of the samples. No quantitative analysis of the organic chemicals was attempted due to time constraints. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.

The objectives of this study were to provide a comprehensive review of the risks and benefits of using adulticides to reduce risk of mosquito-borne disease (particularly West Nile Virus) transmission to humans, as well as to decrease annoyance from nuisance mosquitoes. The study was designed with two major research components, including: 1) an extensive literature review to determine the efficacy of adulticide use, the adverse effects of adulticide use, the impact of mosquitoes on community livability, and the risks and benefits of pesticide use in controlling mosquitoes; and 2) interviews with selected vector districts in seven states to determine effective and ineffective practices in mosquito management. This study has demonstrated that an integrated mosquito management program may be beneficial in reducing risk of disease transmission and mosquito annoyance when performed appropriately. The contribution of adulticiding to reducing mosquito-borne disease transmission, however, is unknown. Research is needed to: 1) further assess the ecological and human impacts of adulticides using the dose and exposure rates realistic to an adulticide program; 2) gain an understanding of the human and ecological impacts of aggregate and cumulative exposures to pesticides, especially for special populations, such as children; and 3) determine the contribution of adulticiding in interrupting or reducing the enzootic amplification of arboviruses, as well as the transmission of WNV to humans. / Graduation date: 2004

This thesis presents a first ever extensive analysis of pesticides in water and sediments from the Okavango Delta, Botswana, employing green sample preparation techniques that require small volumes of organic solvents hence generating negligible volumes of organic solvent waste. Pesticides were extracted and pre-concentrated from water by solid phase extraction (SPE) and headspace solid phase microextraction (HS-SPME) while supercritical fluid extraction (SFE) and pressurized fluid extraction (PFE) were employed for sediments. Subsequent analysis was carried out on a gas chromatograph with electron capture detection and analytes were unequivocally confirmed by high resolution mass spectrometric detection. Hexachlorobenzene (HCB), trans-chlordane, 4,4′-DDD and 4,4′-DDE were detected after optimized HS-SPME in several water samples from the lower Delta at concentrations ranging from 2.4 to 61.4 μg L-1 that are much higher than the 0.1 μg L-1 maximum limit of individual organochlorine pesticides in drinking water set by the European Community Directive. The same samples were cleaned with ISOLUTE C18 SPE sorbent with an optimal acetone/n-hexane (1:1 v/v) mixture for the elution of analytes. No pesticides were detected after SPE clean-up and pre-concentration. HCB, aldrin and 4, 4‟-DDT were identified in sediments after SFE at concentration ranges of 1.1 - 30.3, 0.5 – 15.2 and 1.4 – 55.4 μg/g, respectively. There was an increase of pesticides concentrations in the direction of water flow from the Panhandle (point of entry) to the lower delta. DDE, fatty acids and phthalates were detected after PFE with optimized extraction solvent and temperature. The presence of DDT metabolites in the water and sediments from the Okavango Delta confirm historical exposure to the pesticide. However their cumulative concentration increase in the water-flow direction calls for further investigation of point sources for the long-term preservation of the Delta. The green sample preparation techniques and low toxicity solvents employed in this thesis are thus recommended for routine environmental monitoring exercises.

Thesis (MTech (Chemical Engineering))--Peninsula Technikon, Cape Town, 2003 / The monitoring of pesticide contamination in surface and groundwater is an essential aspect of an assessment of the potential environmental and health impacts of widespread pesticide use. Previous research in three Western Cape farming areas found consistent (37% to 69% of samples) pesticide contamination of rural water sources. However, despite the need, monitoring of pesticides in water is not done due to lack of analytical capacity and the cost of analysis in South Africa. The Solid Phase Microextraction (SPME) sampling method has been developed over the last decade as a replacement for solvent-based analyte extraction procedures. The method utilizes a short, thin, solid rod of fused silica coated with an absorbent polymer. The fibre is exposed to the pesticide contaminated water sample under vigorous agitation. The pesticide is absorbed into the polymer coating; the mass absorbed depends on the partition coefficient of the pesticide between the sample phase and the polymeric coating, the exposure time and factors such as agitation rate, the diffusivity of the analyte in water and the polymeric coating, and the volume and thickness of the coating. After absorption, the fibre is directly inserted into the Gas Chromatograph (GC) injection port for analysis. For extraction from a stirred solution a fibre will have a boundary region where the solution moves slowly near the fibre surface and faster further away until the analyte is practically perfectly mixed in the bulk solution by convection. The boundary region may be modelled as a layer of stationary solution surrounded by perfectly mixed solution.

A prospective ecological risk assessment method was developed evaluating the cumulative probabilistic impact of chemical stressors to aquatic organisms. This method was developed in response to the need to evaluate the magnitude, duration and episodic nature of chemical stressors on aquatic communities under environmental exposure scenarios. The method generates a probabilistic expression of the percent of an ecosystem's species at risk from a designated chemical exposure scenario.

M.Sc. (Zoology) / Concern has been shown by Ezemvelo KZN Wildlife for the state of the Lower Pongolo River and Floodplain due to the ever increasing urban and industrial development in the area. This increase in development poses a threat to the fish populations within the system and their ability to support the surrounding communities. Continued spraying of pesticides e.g. DDT within the area are adding to stresses placed on the fish populations through decreasing water quality. The effectiveness of environmental water flows suggested by White et al. (1984), have never been assessed by conservation authorities. This means that the authorities have been unable to fulfil their legislative obligations to establish management and conservation plans (Hughes et al., 2001). Work on the biological responses of fish to anthropogenic stressors such as organic pollutants and metals; have been conducted by a group of experts in the field of ecological health. This section of the project focusses on two fish species, Hydrocynus vittatus and Synodontis zambezensis, sampled within the study area and used for biomarkers and tissue chemical level determination. Standard techniques were applied for Organochlorine Pesticide (OCP) analysis according to Yohannes et al. (2013) and these results have been compared to biomarker responses which have also been completed following standard protocols. Results found within both fish species, show the relationship between accumulation of toxicants and biomarker responses. The highest levels of ΣOCPs where found within H. vittatus at (Mean ± SE) 1101.61 ± 610.97 ng/g lipid weight, the highest constituent being technical grade Dichlorodiphenyltrichloroethane (DDT). High levels of ΣDDT were also found in S. zambezensis, but were lower than levels in H. vittatus and these levels correspond with positioning of each species within the food web. H. vittatus occupies a much higher level in the food web as they are top predators and S. zambezensis falls lower down on the food web due to their reliance on detritus and only small invertebrate species for food. Biomarker responses are clearly affected by bioaccumulation levels and this is especially evident within H. vittatus as Achetylcholinesterase (AChE) is greatly inhibited by high levels of ΣDDT. Changes in the level of biomarker responses are not as apparent in S. zambezensis and this is believed to be food web linked, due to differences in bioconcentration. Data collected during this study will contribute to baseline data on S. zambezensis and add to already accumulated data on H. vittatus. This new data will also help with the improvement of or alteration to already present monitoring programmes in the study area.

Thesis (M. Tech. - Dept. of Chemistry, Faculty of Applied and Computer Sciences) -- Vaal University of Technology, 2010 / The increased production and application of pesticides for agricultural and non-agricultural purposes has caused the pollution of air, soil, ground and surface water. This has a negative impact on the environment as well as human health due to direct exposure or through residues in food and drinking water. The continuous monitoring of pesticides residues in environmental samples has great importance and demands high efficiency, unique selectivity and high sensitivity techniques. Gas chromatography and high performance liquid chromatography have been established for years as the techniques for the analysis of pesticides residues. The dissertation deals with the qualitative and quantitative determination of selected pesticides in the Southern Gauteng region using Liquid- liquid extraction solid-phase extraction, high performance liquid chromatography, gas chromatography equipped with electron capture detector and gas chromatography mass spectrometry. Liquid-liquid extraction and solid-phase extraction using dichloromethane, hexane and ethyl acetate as the extracting solvent were optimized and evaluated for the determination of pesticides in surface water in the Southern Gauteng region. From the developed method the techniques were applied to water samples taken from different rivers selected namely: Zuikerbosch, Rand Water barrage and Kliprivier for sampling. Dichloromethane was used as a solvent in this study since a recovery test was done between dichloromethane, Ethyl acetate and n-hexane. The percentage recovery test for 4,4-DDT, 4,4-DDE, 2,4-DDD and Endosulfan 1 & 2 ranged from 89.9% -97.3% for dichloromethane, 87.3%-96.8% for hexane 88.4%-97.1% for ethyl acetate. The extracts obtained were subjected to column chromatography for clean up. Thereafter 1µl of the cleaned extracts were injected into the Gas chromatography equipped with an electron capture detector. Organochlorines 4,4-DDT and its metabolites, Organophosphate Chlorypyriphos and carbamates were detected using Gas chromatography electron capture, Gas chromatography mass spectrometry and high performance liquid chromatography.

Environmental toxicologists and public health officials are responsible for assisting in the identification, management, and mitigation of public health hazards. As a result, there is a continued need for robust analytical tools that can aid in the rapid quantification and characterization of chemical exposure. In the first research phase, we demonstrated that a current tool for estimating human organophosphate pesticide exposure, measuring dialkyl phosphate (DAPs) metabolites in urine as chemical biomarkers of pesticide exposure, could represent exposure to DAPs themselves and not to pesticides. We showed that DAPs are metabolically stable, have high oral bioavailability, and are rapidly excreted in the urine following oral exposure. Results suggest that DAP measurements may lead to overestimates of human organophosphate pesticide exposure. In the second phase of research, a quick, easy, cheap, effective, rugged, and safe (QuEChERS) based analytical method was developed and validated for quantifying polycyclic aromatic hydrocarbons (PAHs) in biotic matrices with fat contents that ranged from 3 to 11%. Our method improved PAH recoveries 50 to 200% compared to traditional QuEChERS methods, performed as well or better than state of the art Soxhlet and accelerated solvent extraction methods, had sensitivity useful for chemical exposure assessments, and reduced sample preparation costs by 10 fold. The validated QuEChERS method was subsequently employed in a human exposure assessment. Little is known about how traditional Native American fish smoke-preserving methods impact PAH loads in smoked foods, Tribal PAH exposure, or health risks. Differences in smoked salmon PAH loads were not observed between Tribal smoking methods, where smoking methods were controlled for smoking structure and smoke source. PAH loads in Tribally smoked fish were up to 430 times greater than those measured in commercially available smoked fish. It is not likely that dietary exposure to non-carcinogenic PAHs at heritage ingestion rates of 300 grams per day poses an appreciable risk to human health. However, levels of PAHs in traditionally smoked fish may pose and elevated of risk of cancer if consumed at high rates over a life time. Accurately estimating PAH exposure in cases where aquatic foods become contaminated is often hindered by sample availability. To overcome this challenge, we developed a novel analytical approach to predict PAH loads in resident crustacean tissues based on passive sampling device (PSD) PAH measurements and partial least squares regression. PSDs and crayfish collected from 9 sites within, and outside of, the Portland Harbor Superfund site captured a wide range of PAH concentrations in a matrix specific manner. Partial least squares regression of crayfish PAH concentrations on freely dissolved PAH concentrations measured by PSDs lead to predictions that generally differed by less than 12 parts per billion from measured values. Additionally, most predictions (> 90%) were within 3-fold of measured values, while state of the art bioaccumulation factor approaches typically differ by 5 to 15-fold compared to measured values. In order to accurately characterize chemical exposure, new analytical approaches are needed that can simulate chemical changes in bioavailable PAH mixtures resulting from natural and/or remediation processes. An approach based on environmental passive sampling and in-laboratory UVB irradiation was developed to meet this need. Standard PAH mixtures prepared in-lab and passive sampling device extracts collected from PAH contaminated environments were used as model test solutions. UV irradiation of solutions reduced PAH levels 20 to 100% and lead to the formation of several toxic oxygenated-PAHs that have been previously measured in the environment. Site specific differences in oxygenated-PAH formation were also observed. The research presented in this dissertation can be used to advance chemical exposure estimation techniques, rapidly and cost-effectively quantify a suite of PAHs in biotic tissues, and simulate the effect of abiotic transformation processes on the bioavailable fraction of environmental contaminants. / Graduation date: 2013 / Access restricted to the OSU Community at author's request from April 3, 2013 - April 3, 2014