An assessment of water quality and endocrine disruption activities in the Eerste/Kuils River catchment system, Western Cape, South Africa

[摘要] ENGLISH ABSTRACT: Water quality analysis forms the basis in assessing and monitoring catchments. Asurban development continuously increase, pollution sources increase in either pointsource (wastewater treatment works, industrial effluents) and/or non-point sourceorigin (storm water discharge, domestic pollutants), accumulating pollutants in theenvironment. It was only recently discovered that certain pollutants have subtledisrupting effects on the endocrine system resulting in health related problemsassociated with the reproductive system and thyroid system (growth anddevelopment) of animals and potentially humans. Natural water resourcemanagement proves to include limited biological assays measuring endpoints forcytoxicity, inflammatory activity and endocrine disruption. The broad objective ofthis study was therefore to include several bioassays, not normally used in municipal(City of Cape Town) monitoring programmes, along with water quality data collectedby the City of Cape Town. The Eerste/Kuils River catchment system, Western Cape,under the auspices of the City of Cape Town was chosen, and although this catchmentdoes not contribute to drinking water resources, is subjected to a range ofanthropogenic influences (industrial effluents, household wastewater, agriculturalrunoff). Within the short time-frame available for this study (six months) two months,July (following a dry summer and autumn season) and October (following a wetwinter and early spring season) were selected for water quality monitoring. Spatialvariation (with relevance to specific point and non-point contamination) amongsampling sites were also obtained by choosing several (n=10) along the catchment.Specific aim of the study therefore included: Firstly (Chapter 2), the use of in vitrobioassays, lactate-dehydrolises assay (LDH) for cytotoxic activity, pro-inflammatoryhormone Interleukin-6 (IL-6) secretion by human blood cells and a specificSalmonella ELISA for faecal contamination, in conjunction with routine chemical andbiological (mostly microbiological) monitoring activities. The study indicatedsignificant variation among sites in all microbiological measures as well in IL-6secretion and Salmonella presence. Between months, variations were also evident incertain variables. Secondly (Chapter 3), two bioassays using the yolk precursorprotein, vitellogenin (Vtg) as endpoint was implemented in a) an in vitro Xenopuslaevis liver slice assay (five day exposure) and b) an in vivo Zebrafish (Danio rerio)bioassay (seven day exposure) assessing estrogenic activity in the Eerste/Kuils River catchment. Although estrogen spiked positive control water samples stimulated Vtgproduction in vitro as well as in vivo, no dramatic estrogenic activity was measured atany of the selected sites. Thirdly (Chapter 4), a bioassay using the thyroid controlledmetamorphosis in Xenopus laevis tadpoles to assess effects on the thyroid hormonalsystem was implemented. Thyroid stimulatory activity, compared with a negativecontrol sample, was measured at two sites along the catchment. Although thepractical implementation of the tadpole semi-static exposure protocol (waterreplacement) proved to be labour intensive, all the added bioassays proved to bevaluable tools to add valuable information regarding water quality. It is clear thatmore research related to anthropogenic influences along the Eerste/Kuils Rivercatchment system are needed, specifically in monitoring monthly variations to betterunderstand annual variation in several of the endpoints studied.

[发布机构] Stellenbosch University