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Emerging organic pollutants in sediments from Lake Victoria: Spatial patterns, sources and ecological risks.
Merolyne Natuhwera1, Patrick Ssebugere2, Kenneth Arinaitwe3
1Department of Chemistry, Makerere University, P.O. Box 7062, Kampala, Uganda; Institute of Analytical Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského 9, 812 37 Bratislava, Slovakia.
The Science of the Total Environment
|January 7, 2026
Summary
Contaminants of emerging concern (CECs) were found in Lake Victoria sediments across Uganda, Kenya, and Tanzania. Many detected chemicals pose a high ecological risk to aquatic organisms, necessitating regional action.
Area of Science:
- Environmental Chemistry
- Ecotoxicology
- Analytical Chemistry
Background:
- Lake Victoria faces increasing pollution pressures from diverse anthropogenic sources.
- Contaminants of Emerging Concern (CECs) are widespread but understudied in the Lake Victoria ecosystem.
- Sediments act as a sink for pollutants, potentially impacting benthic organisms.
Purpose of the Study:
- To conduct the first comprehensive evaluation of CECs in Lake Victoria sediments across Uganda, Kenya, and Tanzania.
- To identify and quantify various classes of CECs, including pharmaceuticals, industrial chemicals, and pesticides.
- To assess the ecological risk posed by detected CECs to sediment-dwelling organisms.
Main Methods:
- Wide-scope target screening using ultra-high performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-QTOF-MS).
- Analysis of 38 surface sediment samples collected during the wet season (September 2019).
- Ecological risk assessment using the risk quotient (RQ) method.
Main Results:
- 136 out of over 2400 targeted CECs were detected in Lake Victoria sediments.
- Highest pollutant loads were observed on the northern and northeastern shores, linked to urban and riverine inputs.
- No significant differences in CECs were found across the Ugandan, Kenyan, and Tanzanian sides, indicating trans-boundary pollution.
- 46% of detected CECs posed a high ecological risk (RQ > 1) to sediment-dwelling organisms.
- Pharmaceuticals, plant protection products (PPPs), and industrial chemicals were identified as major threats.
- Seven CECs were prioritized for future monitoring due to high risk scores and potential eco-toxicity.
Conclusions:
- CECs are a significant trans-boundary pollutant issue in Lake Victoria sediments.
- A substantial proportion of detected CECs present a high risk to the lake's ecosystem.
- Urgent need for coordinated regional monitoring, improved wastewater treatment, and sediment-focused risk management strategies.
- Specific compounds like carbamazepine, ibuprofen metabolites, 17-beta estradiol, DEHP, and simazine require particular attention due to their presence and listed hazardous nature.
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