Chemical speciation of copper and cadmium in Kameng river sediments using sequential extraction procedure

Kameng River is a major north bank tributary of the Brahmaputra River and it originates in the Himalayas. The Kameng river traverses through West Kameng and East Kameng districts in Arunachal Pradesh and happens to be the lifeline of the scattered human population within the river basin. To understand the behavior of toxic trace elements in the bed sediments, chemical speciation studies are commonly applied. In this study a modified sequential extraction procedure was applied to study the geochemical partitioning of Cu and Cd in the sediments, their bioavailability and also the degree of risk associated with their remobilization from the sediment matrix. Cadmium was found to be highly associated with the labile fraction in all the sampling sites and thus posed a high risk of remobilization in the water system. Risk assessment criteria applied to the experimental data also suggested high risk of toxicity to living beings due to Cd bioavailability. Cu was found to poses low to medium risk owing to its affinity to the residual and non-labile phases.