Heavymetals pollutants are global concern due to their toxicities and persistence in the environment. Cd isotope signatures in soils and sediments change duringweathering, and it remains unclear if Cd isotopes can effectively trace Cd sources in a riverine system. In this study, we investigate Cd concentration and its isotope compositions, as well as other heavy metals of sediments and related potential Cd sources in a riverine system. The results showed that the two river sediments evaluated were moderately polluted by Zn, Cr, and Cd, while the source samples (soil, sludge, waste, and raw materials) were seriously polluted by heavy metals derived fromanthropogenic activities. According to comprehensive ecological risks, the two sediments have amoderate to lowpotential risk andmore than half of all anthropogenic activities in the study areawere at considerable ormoderate potential risk. We determined that Cd pollution in river sediments was primarily derived from sewage treatment and outlets based on river flow direction and the isotope geochemical behaviors of the Cd isotope in nature conditions. This study further confirmed that analyzing Cd isotopes could be a powerful tool for tracing the source and destination of environmental Cd for multiple sources with similar Cd concentrations. (C) 2020 Elsevier B.V. All rights reserved.