Cd isotopes as a potential source tracer of metal pollution in river sediments

Tracing the sources of heavy metals in water environment is key important for our understanding of their pollution behavior. In this present study, Cd concentrations and Cd isotopic compositions in sediments were determined to effectively identify possible Cd sources. Results showed that elevated concentrations and high enrichment factor for Cd were found in all sediments, suggesting anthropogenic Cd origin. Cd isotopic compositions in sediments yielded relative variations ranged from -0.35‰ to 0.07‰ in term of δ(114/110)Cd (the mean: -0.08‰). Large fractionated Cd was found in sediments collected from a smelter and an E-waste town. Cd isotopic compositions and Cd concentrations measured in sediments allowed the identification of three main origins (dust from metal refining (δ(114/110)Cd < 0), slag of metal refining (δ(114/110)Cd > 0), and those δ(114/110)Cd = 0, such as background and mining activity). According to the actual precision obtained, Cd isotopes could be a potential tool for tracing metal pollution sources in water environment.