Molybdenum pollution and speciation in Nver River sediments impacted with Mo mining activities in western Liaoning, northeast China

The concentrations and speciation of Mo, together with Fe, Cu, and Zn, in Nver River sedi- ments impacted with Mo mining activities in western Liaoning, northeast China, were investigated with geochemical method. Using the X-ray fluorescence and X-Ray diffraction, the characterizations of metals in tailings ponds deposited along the Nver River bank were analyzed. Analysis and comparison of the concentra- tions and speciation of heavy metals show that the maximum concentrations of Fe, Cu, Zn, and Mo detected in river sediments exceed corresponding reference values (S0, P0) by 6.3, 9.7, 16.1, and 494.0 times, respec- tively, and that of Mo exceeds the abundance of Mo in earth's crust by 1127.9 times. High I POLL showed that all of these heavy metals might pose an environmental risk. Bioavailable fractions of Fe, Cu, and Zn were not detected in both tailings ponds and sediments, but that of Mo presented in tailings pond and sediments are 16.15-18.73% and 18.61-59.07%, respectively. The alkaline condition in sediments and tailings ponds is a significant factor governing chemical speciation of heavy metals. This study indicates that Mo tailings ponds deposited along the bank may have a closely relationship with the high levels of these metals in sediments and Mo in sediments may pose a high risk to the local environment.