With the successful developments of the analytical protocols for Sr, Pb, Fe, and Mo isotopes in environmental water samples last year, we further apply these methods to investigate pollution sources of heavily polluted rivers in Taiwan, i.e., the Jishui River and the Agondian River. With assistance from EAL, we have completed water samplings for river water and wastewater from different types of industries in the two river catchments. Concentrations of major and trace elements and Sr-Pb-Fe-Mo isotope ratios were analyzed for the total recoverable fractions (NIEA W313.54B) of the water samples. The results of metal concentrations show spatial and temporal variations in the studied rivers, most likely reflecting mixings between natural and anthropogenic inputs in the catchment scale. Continuous monitoring at the pollution hot spots in both rivers indicates that elements behave differently during rain events. For example, elevated Fe and Pb concentrations were observed in the rain events, while concentrations of Sr and Mo decreased. In contrast, the variations of heavy metal concentrations (e.g., Ni, Cu, and Zn) did not follow the concentrations of suspended particles in the Agondian River, suggesting significant influences of anthropogenic inputs in this river catchment. The isotope compositions of Sr, Pb, and Fe in the Agondian River are distinctively different between natural (river water) and anthropogenic (wastewater) sources. The Fe-Pb isotope ratios indicate that high concentrations of Fe and Pb during the rain events are mainly derived from natural sources, whereas it shows more anthropogenic contributions when there is no rain. This study confirms the great potential of using metal isotopes for tracing sources of metal pollutions in river catchments, and measurements on isotopic signatures of different industries/factories within the studied catchment are required to better constrain the relative contributions from natural and anthropogenic sources.

MC-ICP-MS, aquatic environment, metal pollution