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Evaluating the Occurrence, Fate and Human Health Risks of Contaminants of Emerging Concern in the Atlantis Managed Aquifer Recharge Scheme
Thesis (MSc)--Stellenbosch University, 2026.
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2026
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| _version_ | 1867613971511508992 |
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| access_status_str | Open Access |
| author | Mokhethi, Maposholi Faith |
| author2 | Chow, Reynold |
| author_browse | Chow, Reynold Mokhethi, Maposholi Faith |
| author_facet | Chow, Reynold Mokhethi, Maposholi Faith |
| author_sort | Mokhethi, Maposholi Faith |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc)--Stellenbosch University, 2026. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/136179 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:44:37.487Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/136179 Evaluating the Occurrence, Fate and Human Health Risks of Contaminants of Emerging Concern in the Atlantis Managed Aquifer Recharge Scheme Mokhethi, Maposholi Faith Chow, Reynold Roychoudhury, Alakendra Towers, Luke Stellenbosch University. Faculty of Science. Dept. of Earth Sciences. Thesis (MSc)--Stellenbosch University, 2026. Mokhethi, M. F. 2026. Evaluating the Occurrence, Fate and Human Health Risks of Contaminants of Emerging Concern in the Atlantis Managed Aquifer Recharge Scheme. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/9954516d-4a28-481d-b1aa-005325a31299 Managed aquifer recharge (MAR) using stormwater and treated effluent is a vital strategy for sustaining urban aquifers used for potable supply in water-scarce regions. However, the quality of these recharge waters is a concern, as they often contain contaminants of emerging concern (CECs) that may persist in groundwater and pose risks to human health if left untreated. This study aims to evaluate the impact of MAR on groundwater quality in the Atlantis Aquifer by assessing the occurrence and spatial distribution of 12 classes of CECs, including pharmaceuticals, pesticides, and industrial chemicals. In addition, it evaluates potential human health risks associated with exposure to CECs and assesses the aquifer’s natural attenuation capacity, given the absence of advanced treatment either prior to recharge or post abstraction within the current MAR scheme. Samples were collected in 2019, 2021, and 2023 from MAR source water, groundwater, and surface water and analysed for 127, 289, and 649 compounds, respectively. Detections and concentrations were highest in MAR source water, followed by MAR-impacted groundwater, while naturally recharged groundwater had the fewest detections, indicating that most CECs enter the aquifer via MAR. There is, however, a baseline level of contamination in naturally recharged groundwater sourced from nearby urban, agricultural and industrial land uses. A three-tiered human health risk assessment showed that fewer than 20% of compounds in 2019 and 2021 across all tiers had risk quotients (RQs) exceeding 1, indicating that most detected compounds are below their respective drinking water benchmarks. However, given that multiple CECs co-occur in the MAR system, further research is needed to evaluate potential health risks from mixtures. Dilution of MAR-impacted groundwater by naturally recharged groundwater from the Witzands Wellfield was identified as an effective step in reducing CEC concentrations and ultimately reducing potential health risks. The aquifer’s attenuation capacity was assessed using long-term water quality monitoring data (2018 – 2024) for redox-sensitive species (e.g., manganese, iron, nitrate), with changes in their concentration along the Witzands MAR flow path suggesting that biodegradation, in addition to dilution by ambient groundwater, likely plays a key role in the attenuation of CECs. While most compound concentrations decreased along the Witzands MAR flow path, per- and polyfluoroalkyl substances (PFAS) exhibited contrasting behaviour, with both concentrations and RQs increasing along the flow path. Moreover, RQs exceeding 1, based on United States Environmental Protection Agency (USEPA) 2024 standards, were recorded in the abstracted groundwater blend from the Witzands Wellfield, suggesting that there is potential to cause adverse human health effects. These results indicate the necessity for advanced treatment after abstraction. Granular activated carbon is recommended, given its cost-effectiveness and proven efficacy in removing long-chain PFAS, which are the compounds that consistently had RQs > 1. Beyond informing safe operational management for the Atlantis MAR scheme with respect to CECs, the insights from this study will guide the development of a CEC monitoring framework for South Africa’s other MAR schemes in development, as well as other schemes worldwide where treated effluent is considered for use as MAR source water. Masters 2026-04-24T09:20:56Z 2026-04-24T09:20:56Z 2026-03 Thesis https://scholar.sun.ac.za/handle/10019.1/136179 en Stellenbosch University 240 pages application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Mokhethi, Maposholi Faith Evaluating the Occurrence, Fate and Human Health Risks of Contaminants of Emerging Concern in the Atlantis Managed Aquifer Recharge Scheme |
| title | Evaluating the Occurrence, Fate and Human Health Risks of Contaminants of Emerging Concern in the Atlantis Managed Aquifer Recharge Scheme |
| title_full | Evaluating the Occurrence, Fate and Human Health Risks of Contaminants of Emerging Concern in the Atlantis Managed Aquifer Recharge Scheme |
| title_fullStr | Evaluating the Occurrence, Fate and Human Health Risks of Contaminants of Emerging Concern in the Atlantis Managed Aquifer Recharge Scheme |
| title_full_unstemmed | Evaluating the Occurrence, Fate and Human Health Risks of Contaminants of Emerging Concern in the Atlantis Managed Aquifer Recharge Scheme |
| title_short | Evaluating the Occurrence, Fate and Human Health Risks of Contaminants of Emerging Concern in the Atlantis Managed Aquifer Recharge Scheme |
| title_sort | evaluating the occurrence fate and human health risks of contaminants of emerging concern in the atlantis managed aquifer recharge scheme |
| url | https://scholar.sun.ac.za/handle/10019.1/136179 |
| work_keys_str_mv | AT mokhethimaposholifaith evaluatingtheoccurrencefateandhumanhealthrisksofcontaminantsofemergingconcernintheatlantismanagedaquiferrechargescheme |