School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou, China.
School of Energy and Environment, City University of Hong Kong, Hong Kong SAR, China.
Nat Commun. 2024 Oct 26;15(1):9262. doi: 10.1038/s41467-024-53479-9.
Methylmercury (MeHg) in aquatic systems poses a serious public health risk through bioaccumulation in the aquatic food web. In recent years, MeHg has been observed to increase to concerning levels globally in rivers near cities; however, the causes of this increase are not well understood. Here, we demonstrate the significant role of sewage contamination by analyzing over 1,300 publicly available metagenomes in urban rivers worldwide, and conducting experiments with water samples across China. We find that sewage contamination significantly increases the abundance of mercury (Hg)-methylating microorganisms in urban rivers globally. This increase is primarily attributed to the high abundance of active Hg-methylating microorganisms in sewage, which migrate to rivers via direct discharge or combined sewer overflows (CSOs), becoming key contributors to elevated riverine MeHg levels. Our findings underscore the importance of effectively eliminating Hg-methylating microorganisms from sewage to mitigate the public health risks associated with MeHg in urban rivers.
水体中的甲基汞（MeHg）通过在水生食物链中的生物累积，对公共健康构成严重威胁。近年来，人们观察到全球城市附近河流中的 MeHg 含量增加到令人担忧的水平，但这种增加的原因尚不清楚。在这里，我们通过分析全球城市河流中超过 1300 个公开可用的宏基因组，并对中国各地的水样进行实验，证明了污水污染的重要作用。我们发现，污水污染会显著增加全球城市河流中汞（Hg）甲基化微生物的丰度。这种增加主要归因于污水中活性 Hg 甲基化微生物的高丰度，它们通过直接排放或合流制污水溢流（CSO）迁移到河流中，成为导致河流中 MeHg 水平升高的关键因素。我们的研究结果强调了从污水中有效消除 Hg 甲基化微生物的重要性，以减轻与城市河流中 MeHg 相关的公共健康风险。
