Browsing by Author "Petrik, Leslie"

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Open Access
    A sea of contested evidence: Disputes over coastal pollution in Hout Bay, Cape Town, South Africa
    (2022) Beukes, Amy; Green, Lesley; Petrik, Leslie
    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.
  • Thumbnail Image
    Item
    Open Access
    Atrazine: a lively chemical journey
    (2023) Dornbrack, Kevin; Twidle, Hedley; Petrik, Leslie
    Atrazine is a widely used pesticide, particularly popular in corn plantations for its herbicidal properties of killing and preventing the growth of certain weeds and grasses. Evidence of its neurotoxicity, hormone disruption and reproductive toxicity led the EU to ban the chemical in 2003. Despite long standing evidence of its harm, South Africa continues to use atrazine, the majority of which is imported from the EU. Drawing on South Africa as a case study, I illustrate Atrazine's unique journey through South Africa's political economic landscape, interpreted in relation to those of the USA and EU, highlighting that problems of chemical pollution are political as much as they are molecular. In this project, I have employed biochemical, epidemiological, historical, social and political scientific approaches to form an interdisciplinary understanding of atrazine's biochemical, ecological, and economic effects; how its harm lands unevenly on poor and marginalized people, often in the global south; and how commercial and governmental structures enable and maintain its use. This interdisciplinary understanding of atrazine's uneven effects as well as its varied socio-political figurations illustrates how and why regulatory processes have proved vastly inadequate to curtail the chemical pollution caused by atrazine and many other pesticides. The results of this research should hopefully serve as a case study and cautionary tale of globally increasing and unevenly experienced chemical exposure. This project argues that effects of atrazine within their political and historic contexts should be considered a form of unspectacular violence, that slowly but persistently degrades quality of life. By tracing the networks of atrazine's chemical relations, this project illustrates that the molecular is always political.
  • Thumbnail Image
    Item
    Open Access
    Is our evidence contaminated? Tracing the ways in which proof is validated in the context of Cape Town's marine effluent outfalls
    (2021) Zackon, Melissa Amy; Green, Lesley; Petrik, Leslie
    The effects on seawater quality from Cape Town's marine outfalls and their use for sewage disposal has been a concern for local residents for over a century. This dissertation explores the production of scientific evidence that contrasts public experience and independent science. Beginning with the 2015 application by the City of Cape Town (CoCT) for a permit renewal to continue discharging 38 million cubic meters of sewage daily off the city's Atlantic coast, the study considers the arguments of concerned citizens, photographers and independent scientists who warned that the outfalls are responsible for poor seawater quality. This dissertation begins by tracing the contemporary experiences of concerned citizens as they discovered that the outfall was polluting the ocean and then considers the evidence utilised by the CoCT in their responses to these concerns and in their permit application. The study finds that the CoCT's commissioned CSIR report and the use of tourism-orientated Blue Flag criteria are not compatible with the public interest and independent findings, and further finds that a managerialist approach to scientific data has confused the fulfilment of departmental mandates with the public interest, though they are not the same thing. Through the signing of international treaties, its constitution and various legislations, South Africa prescribes to the precautionary principle, but the author argues that this principle has not been applied in this scenario and that retrospective attitudes towards beach management and seawater quality concerns have been applied instead. Consequently, the implementation of a proactive and forward-looking procedure is recommended, and transparency, ocean modelling and the precautionary principle should be applied to the management of Cape Town's marine outfalls and to concerns over its water quality and attendant data.
  • No Thumbnail Available
    Item
    Open Access
    Persistent pharmaceutical concentrations in an urban Western Cape Estuary and the effects on microalgal assemblages
    (2025) Murgatroyd, Olivia; Pillay, Deena; Petrik, Leslie
    Coastal environments comprise distinct and diverse ecosystems of economic and ecological significance that provide invaluable ecosystem functions and services to humans. Despite their significance, coastal environments worldwide are experiencing deterioration due to the growth of the human population and associated activities in coastal areas. Chemicals of emerging concern, including pharmaceuticals and personal care products, are a prominent example of an emerging threat to coastal environments due to their ubiquity and persistence in marine environments globally. However, research on levels of pharmaceutical pollution and associated effects on ecological processes and biota in estuaries is severely lacking in South Africa. Therefore, the consequences for key estuarine biota and the functions they provide are largely unknown, to the best of my knowledge. Therefore, the purpose of this study was to address the above-mentioned knowledge gaps on pharmaceutical pollution in South Africa. This aim was addressed by firstly determining the concentration of pharmaceuticals in the Zandvlei Estuary, which is an urbanized, anthropogenically manipulated system in the Western Cape, South Africa. Thereafter, the interaction between sulfamethoxazole presence and sandprawn density was quantified experimentally to understand the responses of microalgae biomass. An experiment was conducted as the consequences of pharmaceutical pollution on functionally important estuarine biota such as sandprawns and the functions they provide including biofiltration in South African estuaries are, to the best of my knowledge, unknown. Based on field sampling, high concentrations of pharmaceuticals were recorded in the Zandvlei Estuary, particularly near the mouth, where acetaminophen had the highest average concentration in water samples among all sites (4.604 ± 0.453 μg/L) and the highest average concentration in sandprawn samples (11.309 μg/g). Additionally, pharmaceuticals including sulfamethoxazole, carbamazepine and diclofenac were detected in water samples in all sites and all sandprawn samples. With the use of environmentally relevant sulfamethoxazole concentrations in a laboratory mesocosm experiment, I found that sulfamethoxazole presence negatively affected pelagic microalgae biomass, where micro- and picoplankton declined with sulfamethoxazole concentrations but nanoplankton and benthic microalgae was unaffected. The high levels of pharmaceuticals found in the Zandvlei Estuary are likely a result of increasing sewage spills due to malfunctioning sewage pump stations, which in turn is likely amplified by load shedding (planned electricity outages to manage demand) intensifying over the last seven years. Findings additionally highlight the potential for small, urban temporary-open closed estuaries to be accumulation sites for chemicals of emerging concern, given the order of magnitude greater values recorded in the Zandvlei Estuary compared to False Bay. Moreover, this study has shown that increasing sulfamethoxazole concentrations cause a reduction in phytoplankton biomass and a shift in size classes. These findings need further research to understand ecological repercussions for food web topology and efficiency, for example, given that changes in phytoplankton abundance and traits can generate indirect bottom-up changes to higher trophic levels.