Background

Within the last decades, there has been increasing research on the occurrence of chemicals of emerging concern (CECs) in aquatic ecosystems due to their potential adverse effects on freshwater organisms and risk to human health. However, information on CECs in freshwater environments in sub-Saharan countries is very limited. Here, we investigated the occurrence of CECs in snails and sediments collected from 48 sites within the Lake Victoria South Basin, Kenya, which have been previously investigated for water contamination. Samples were analyzed by liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) with a target list of 429 compounds.

Results

In total, 30 compounds have been detected in snails and 78 in sediment samples, compared to 79 previously identified compounds in water. By extending the monitoring of CECs to snails and sediments, we found 68 compounds that were not previously detected in water. These compounds include the anti-cancer drug anastrozole, detected for the first time in the Kenyan environment. Individual compound concentrations were detected up to 480 ng/g wet weight (N-ethyl-o-toluenesulfonamide) in snails and 110 ng/g organic carbon (pirimiphos-methyl) in sediments. Higher contaminant concentrations were found in agricultural sites than in areas not impacted by anthropogenic activities. Crustaceans were the organisms at greatest toxic risk from sediment contamination [toxic unit (TU) up to 0.99] with diazinon and pirimiphos-methyl driving this risk. Acute and chronic risks to algae were driven by diuron (TU up to 0.24), whereas fish were found to be at low-to-no acute risk (TU up to 0.007).

Conclusions

The compound classes present at the highest frequencies in all matrices were pesticides and biocides. This study shows substantial contamination of surface water in rural western Kenya. By filling data gaps on contamination of sediments and aquatic biota, our study reveals that CECs pose a substantial risk to environmental health in Kenya demanding for monitoring and mitigation.

中文翻译：

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肯尼亚西部淡水系统中新兴关注化学品的多隔室化学表征和风险评估

背景

在过去的几十年中，由于其对淡水生物的潜在不利影响以及对人类健康的危害，对水生生态系统中新出现的化学物质（CEC）的发生的研究日益增多。但是，关于撒哈拉以南国家淡水环境中CEC的信息非常有限。在这里，我们调查了从肯尼亚维多利亚湖南盆地内48个地点收集的蜗牛和沉积物中CEC的发生情况，这些地点之前已进行过水污染调查。通过液相色谱与高分辨率质谱法（LC-HRMS）耦合分析样品，目标化合物为429种。

结果

总共在蜗牛中检出30种化合物，在沉积物样品中检出78种化合物，而先前在水中鉴定出79种化合物。通过将CEC的监测范围扩展到蜗牛和沉积物，我们发现了以前在水中未发现的68种化合物。这些化合物包括在肯尼亚环境中首次检测到的抗癌药阿那曲唑。检测到的单个化合物浓度最高为480 ng / g湿重（N蜗牛中的-乙基-邻甲苯磺酰胺）和沉积物中的110 ng / g有机碳（嘧啶-甲基）。在农业场所发现的污染物浓度高于不受人为活动影响的区域。甲壳类动物是受到沉积物污染（毒性单位（TU）高达0.99）的最大毒性风险的生物，其中二嗪农和吡虫啉甲基导致了这种风险。敌草隆导致藻类的急性和慢性风险（TU高达0.24），而鱼类则处于低到无急性风险中（TU高达0.007）。

结论

在所有基质中出现频率最高的化合物类别是农药和杀生物剂。这项研究表明肯尼亚西部农村地区的地表水受到严重污染。通过填补关于沉积物和水生生物污染的数据空白，我们的研究表明，CEC对肯尼亚的环境健康构成了重大风险，需要进行监测和缓解。