Centre for Environment and Development, Ashoka Trust for Research in Ecology and the Environment, Jakkur, Bengaluru, India.
Ambio. 2022 Oct;51(10):2182-2200. doi: 10.1007/s13280-022-01734-y. Epub 2022 Jun 8.
Heavy metal (HM) contamination of water bodies is caused by both first generation (industries) and second generation (distributed sources, domestic sewage, sediments) sources. We applied a multi-pronged approach to quantify the contribution of first and second generation sources to the HM load in a stream located in an industrialised catchment. We found that, despite strict regulation, first generation sources contributed significantly to the HM load (60%-80%), showing the ineffectiveness of current regulation. Domestic sewage contributed significantly to Cu, Ni, and Mn load (15%-20%). The contribution of distributed sources and sediments to HM load is insignificant. In a 24-hour cycle, HM concentrations frequently exceeded FAO's irrigation water quality standards, with the highest concentrations observed at night. Empirically, the study highlights the continued plight of urban streams in rapidly industrialising centers and the failure to regulate first-generation sources. Methodologically, it demonstrates the importance of temporally intensive measurement of contaminant concentration and load. Policy implications include the need for ambient water quality standards, inclusion of HMs in such standards, load-based regulation, and a problem-oriented monitoring and enforcement approach.
水体中的重金属(HM)污染是由第一代(工业)和第二代(分散源、生活污水、沉积物)源造成的。我们采用了多管齐下的方法来量化位于一个工业化流域中的溪流中第一代和第二代源对 HM 负荷的贡献。我们发现,尽管有严格的规定,但第一代源对 HM 负荷的贡献(60%-80%)仍然很大,这表明当前的规定是无效的。生活污水对 Cu、Ni 和 Mn 的负荷贡献(15%-20%)很大。分散源和沉积物对 HM 负荷的贡献并不显著。在 24 小时的周期内,HM 浓度经常超过粮农组织灌溉水质标准,夜间浓度最高。经验上,该研究突出了快速工业化中心城市溪流的持续困境以及未能对第一代源进行监管。从方法论上讲,它展示了对污染物浓度和负荷进行时间密集型测量的重要性。政策影响包括需要制定环境水质标准、将重金属纳入此类标准、基于负荷的监管,以及采用面向问题的监测和执法方法。