Iron and Molybdenum Isotope Application for Tracing Industrial Contamination in a Highly Polluted River

Rivers adjacent to industrial zones usually suffer from severe pollution issues. Industrial wastewater that has undergone sewage treatment processes may be legally discharged into rivers under water quality permits. Previous studies have frequently employed isotopic tracers to identify potential contaminants for pollution control. Conventional radiogenic isotopes utilized in tracing studies cannot discern whether the source is untreated (primary) industrial wastewater, which can have serious impact to the environment. By analyzing the iron (Fe) and molybdenum (Mo) isotopic compositions in original industrial wastewater and treated effluent, this study aims to investigate whether the heavily polluted Agongdian River is contaminated by the untreated wastewater. Based on the results from this study, the original industrial wastewater exhibits higher concentrations of metallic elements and heavier Fe and lighter Mo isotopic compositions, compared to the treated effluent. Consequently, it appears that Agongdian River water indeed exhibits evidence of untreated industrial wastewater. Furthermore, the volume of original industrial wastewater entering the river can be estimated from these results. This research offers a more precise and accurate approach to monitor potential industrial wastewater pollution in natural water bodies, contributing to the goal of environmental protection and sustainable development.