The City of Cape Town's (CoCT) wastewater management system discharges effluent from households, industries and other sources into the Atlantic Ocean through deep-water marine outfalls in Green Point, Camps Bay and Hout Bay. At total capacity, these three outfalls discharge 55.3 megalitres (Ml) into marine receiving environments daily. With minimal pre-treatment that amounts to screening and sieving, this results in microbial and chemical pollution of the sea (including chemicals of emerging concern), marine organisms, recreational beaches, and Marine Protected Areas (MPAs). This research focuses on contestations over evidence of that pollution in Hout Bay. The study documents the work of independent scientists seeking to provide evidence of coastal pollution obtained via microbial and chemical analyses of water (coastal and inland) and marine organisms (Mytilus galloprovincialis) samples. It also presents accounts of pollution obtained via ethnographic research with local residents, fishers, frequent water users and river activists who have observed and experienced poor coastal water quality. However, the form of evidence that is considered and informs decision-making processes by the CoCT has consistently sought to invalidate these forms of evidence, from both independent scientists and the public. Debates around knowledge of water and contests over evidence that highlight the entanglements of science, politics, and ways of knowing make visible a consistent pattern in coastal water-quality governance by the City, which results in inaction regarding the ever-growing issue of coastal pollution in Cape Town.

Dans les filtres plantés de roseaux à écoulement vertical, la percolation des eaux usées à travers le milieu filtrant entraine la rétention physique des matières en suspension à la surface des filtres, et leur accumulation conduit à la formation d’une couche de boue principalement sur le premier étage des filtres. Longtemps considérée comme un facteur de risque de colmatage, cette couche de surface est aussi un compartiment majeur de la performance du système. Dans l’objectif de mieux connaitre la nature et l’évolution des dépôts qui la constituent, des échantillons issus de 14 stations en fonctionnement ont été prélevés pour analyser notamment la nature de leur matière organique particulaire et son évolution. Les résultats ont montré que les dépôts de stations de plus de trois ans de fonctionnement tendent vers un état similaire, caractérisé par la présence de composés organiques stables et complexes et par une plus faible réactivité de la matière organique particulaire. Les dépôts provenant de stations de moins d’un an de fonctionnement présentent une signature particulière, caractérisée par une matière organique réactive et peu mature. En complément de cette évolution en surface du filtre, la matière organique particulaire des eaux usées entrantes peut également subir des modifications au sein du process d’un filtre planté de roseaux. La présence d’un lit bactérien comme traitement additionnel participe à l’hydrolyse et à la transformation de la matière organique particulaire par des processus de minéralisation et d’humification. L’ajout de chlorure ferrique favorise l’agrégation de la matière. Enfin, des polluants organiques et métalliques d’intérêt ont fait l’objet d’une première quantification dans ces dépôts afin d’estimer leur rétention pour mieux appréhender les risques potentiels en cas de dysfonctionnement ou d’épandage. L’étude du comportement à la lixiviation en fonction du pH a permis de mettre en évidence que la libération de certains éléments traces est liée à celle de la matière organique. / The percolation of unsettled wastewater in French Vertical Flow Constructed Wetlands (VFCWs) causes the formation of a sludge layer at the surface of the first stage filter due to the retention of sludge deposits. Although the growth of this layer over the years of operation is a potential source of clogging risks, it also largely contributes in the performance of the system, depending on its properties. In order to better understand these phenomena, surface sludge deposits samples taken from 14 VFCW sewage treatment plants were collected and analyzed. Results showed that the structure and composition of the sludge deposits from treatment plants with more than three years of operation time were remarkably similar, characterized by the presence of stable and complex organic compounds and a low reactivity and biodegradability of the particulate organic matter. Deposits from treatment plants with less than one year of operation time were composed of more reactive and less mature organic matter. The particulate organic matter of the inflow wastewater was also shown to undergo modifications within the treatment chain of the vertical flow constructed wetland. The implementation of a biological trickling filter as an additional treatment prior to the filter stages was found to induce the transformation of soluble and particulate organic matter through mineralization and hydrolysis, and to contribute to humification probably by the detachment of biofilm fragments. The injection of ferric chloride used to precipitate phosphates was found to promote aggregation within the sludge deposits. Finally, the role of the sludge layer in the retention of a selection of organic and metallic pollutants in VFCW systems has been evaluated by analyzing sludge deposits samples. Detergents were found at higher concentrations than PCPP. The potential release of the sorbed contaminants was studied using leaching tests as a function of pH. Results showed that the release of some trace metals (mostly copper) was governed by the leaching behavior of organic matter.

Gestillte Kinder sind über die Muttermilch mit persistenten organischen Schadstoffen (POPs) belastet. Tierexperimentelle Studien deuten auf eine besondere Empfindlichkeit des sich entwickelnden Immunsystems für POPs hin. Mögliche Effekte dieser Verbindungen auf den kindlichen Organismus sind bisher kaum untersucht. Es wurden potenzielle Einflüsse verschiedener POPs (PCDDs, PCDFs, PCBs, beta-HCH, HCB und pp-DDE) auf natürliche Killerzellen (NK-Zellen) und NK-Aktivität bei gestillten im Vergleich zu nicht gestillten Kindern untersucht. NK-Zellen sind eine Lymphozytensubpopulation (CD3-CD56/16+), die über ihre zytotoxische Aktivität allogene, virusinfizierte und maligne Zellen ohne vorherige Sensibilisierung töten kann. Es wurden 66 gesunde Kinder im Alter von 11-12 Monaten untersucht, davon waren 50 Kinder mindestens 4 Monate lang voll gestillt und 16 Kinder nicht gestillt. Aus einer Region mit bekannter erhöhter PCDD/PCDF-Belastung stammten 13 gestillte Kinder. Die NK-Zellzahlen wurden mittels Immunphänotypisierung am Durchflusszytometer bestimmt. Die Aktivität der NK-Zellen wurde mit einem nicht-radioaktiven, durchflusszytometrischen Zytotoxizitäts-Assay gemessen. Die POP-Konzentrationen im Blutfett der Probanden wurden kommerziell bestimmt. Weder bei den NK-Zellzahlen, noch bei der NK-Aktivität konnten zwischen den gestillten und nicht-gestillten Kindern signifikante Unterschiede im t-Test nachgewiesen werden. In Korrelationsanalysen zeigten sich keine signifikanten Einflüsse der POP-Konzentrationen auf NK-Zellzahlen und NK-Aktivität. Im Laufe der Untersuchung zeigte sich, dass der eingesetzte Zytotoxizitäts-Assay nur semiquantitative Daten lieferte. Die vorliegenden Ergebnisse und weitere Befunde bezüglich des Immunsystems der Probanden weisen darauf hin, dass die relativ hohe Belastung lange gestillter Säuglinge mit POPs nicht zu einer biologischen Wirkung im kindlichen Organismus führt. Angesichts der nachgewiesenen positiven Effekte des Stillens, kann diesbezüglich die bestehende Stillempfehlung bekräftigt werden. / Breast-fed infants are exposed to persistent organic pollutants (POPs) via breast milk. Animal studies indicate a special sensitivity of the maturing immune system to POPs. Possible effects of these compounds on the infantile organism are so far barely examined. Potential influences of several POPs (PCDDs, PCDFs, PCBs, beta-HCH, HCB and pp-DDE) on natural killer (NK) cells and NK activity of breast-fed infants in comparison to formula-fed infants were investigated. NK cells are a subset of lymphocytes (CD3-CD56/16+) that can kill allogeneic, virus-infected and malignant cells via their cytotoxic activity without prior sensitization. The study group consisted of 66 healthy infants examined at age 11 to 12 months, of which 50 infants were breast-fed and 16 infants were formula-fed. 13 breast-fed infants came from a region with known increased PCDD/PCDF-burden. Numbers of NK cells were measured by flow cytometric immunophenotyping. NK activity was analysed by a non-radioactive flow cytometric cytotoxicity assay. POP concentrations in the blood fat of the probands were calculated commercially. There were no significant differences between breast-fed and formula-fed infants concerning number and activity of NK cells in the t-test. Analysis of correlation showed no significant influences of POP concentrations on the number and activity of NK cells. In the course of the study the data obtained by the employed cytotoxicity assay proved to be only semiquantitative. The presented findings and further results concerning the immune system of the study subjects suggest that the relatively high burden of long-term breast-fed infants with POPs does not lead to a biological effect in the infantile organism. Regarding the proven positive effects of breast-feeding the existing recommendation to breastfeed can be encouraged.

MENVSC / Department of Hydrology and Water Resources / Sewage sludge (biosolids) from wastewater treatment plants (WWTPs) has been widely used as a soil improver in Europe, United States of America and some developing countries including South Africa. It has its benefits for farmers as a good source of organic matter and minerals, however, sludge after treatment still contains pathogenic organisms, heavy metals and persistent organic pollutants (POPs). The POP and heavy metal contaminants that accumulate in sludge may transfer through the food chain and cause adverse effects on human beings. In this study, a field experiment was carried out on farmland fertilized with sewage sludge from a wastewater treatment plant (WWTP) that vasically receives domestic wastewater and storm water. Vegetable spinach (Spinacia oleracea) was used for this study and was planted on a farmland under controlled conditions. Ten ridges each of dimensions 20 m × 0.3 m was made and dry sludge weights of 5, 10, 15, 20, 25, 30, 35, 40, 45 and 50 kg were applied as manure on each of the ridges, respectively. Representative samples of sludge and soil were taken for analysis of heavy metals and POPs. At maturity, in twelve weeks, the root and leave samples of the vegetable were taken from all the ridges including the control. The soil, sludge, and vegetable samples were analyzed for total heavy metal content (Cd, Cr, Cu, Ni, Pb, Co, Zn, Al, Fe, Mn), speciated heavy metal content and POP (PAH, PCB). Soil and sludge samples were also analyzed for total organic content, pH, cation exchange capacity (CEC), conductivity and alkalinity. The analysis for total heavy metals and speciated heavy metal content was carried out using inductively coupled plasma optical emission spectrophotometer (ICP-OES), and CEC analysis was carried out using atomic absorption spectrophotometer (AAS). A two-dimensional gas chromatograph with time of flight mass spectrometry detector (GC X GC TOFMS) was used for POP measurements. pH measurement was made using a pH meter and conductivity measurement using a conductivity meter. Alkalinity and total organic content analysis was performed using titrimetric apparatus. The highest total heavy metal concentration of 378.9 mg / kg was recorded in Fe metal in soil and Leaf sample while the lowest total metal concentration of 0.0003 mg / kg was in Cu metal in root sample. The highest heavy metal concentration of 1002 mg / kg in speciated forms was in Mn metal in F1 fraction and the lowest of 0.0004 mg / kg was in Cd metal in F5 fraction. PAHs were only found in soil samples and their concentrations ranged from 2.53 mg / kg to 146.5 mg / kg. There were no PCB detected in all the samples analysed. The results indicated that the trace metals concentrations found in the exchangeable fraction were higher than those observed in any of the preceding extractions except in the case of Cd, Cr, Fe and Pb where Fe-Mn oxide and organic matter fractions predominated and were closely followed by exchangeable fraction.

In the United Nations Convention on the Law of the Sea, the environmental protection of the marine environment was first addressed in a comprehensive manner on an international level. However, the Convention distinguishes between four different sorts of pollution depending on which source the pollution originates from. Still, one of these sources play a more crucial role in the protection of the marine environment than the other since that source is estimated to stand for 80 percent of all the marine pollution; namely marine pollution from land-based sources. As the throw-away culture has led to products being disposed of at a faster rate than ever before, in particular plastic products, the amount of land-based debris has also substantially increased over the last decades. This increased disposal rate of products in combination with poor waste treatment has consequently led to many kinds of wastes ending up in the ocean and causing severe harm, not only to the marine environment and its living species, but also to humans that eat the fish and use the many other ecosystem services of the Sea. In this thesis, some prominent international conventions on marine pollution from land-based sources are examined; namely the United Nations Convention on the Law of the Sea, the Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and their Disposal, as well as the Stockholm Convention on Persistent Organic Pollutants. To achieve United Nations Sustainable Development Goal number 14.1 to significantly reduce marine pollution from land-based sources by 2025, this thesis claims that international laws addressing this sort of pollution need to be implemented. Moreover, this thesis rests on the belief that regional implementation is a crucial component in making states align with international law. However, while regional implementation has been ambitious in the European Union Law, many regions still lack enforceable frameworks that aim to reduce and prevent marine pollution from land-based sources.