Dissolved trace element biogeochemistry of a tropical river, Southwestern India.

River Swarna, a small tropical river originating in Western Ghats (at an altitude of 1,160 m above mean sea level) and flowing in the southwest coast of India discharges an average of 54 m(3)s(-1) of water into the Arabian Sea, of which significant part is being discharged during the monsoon. No studies have been made yet on the water chemistry of the Swarna River basin, even as half a million people of Udupi district use it for domestic and irrigational purposes. As large community in this region depends on the freshwater of Swarna River, there is an urgent need to study the trace element geochemistry of this west flowing river for better water management and sustainable development. The paper presents the results on the biogeochemistry of dissolved trace elements in the Swarna River for a period of 1 year. The results obtained on the trace elements show seasonal effect on the concentrations as well as behavior and thus forming two groups, discharge driven (Li, Be, Al, V, Cr, Ni, Zr, In, Pb, Bi and U) and base flow driven (groundwater input; Mn, Fe, Co, Cu, Ga, Zn, As, Se, Rb, Sr, Ag, Cd, Cs, Ba and Tl) trace elements in Swarna River. The biogeochemical processes explained through Hierarchical Cluster Analysis show complexation of Fe, Ga and Ba with dissolved organic carbon, redox control over Mn and Tl and biological control over V and Ni. Also, the water quality of Swarna River remains within the permissible limits of drinking water standards.