TRACE-ELEMENT CHEMISTRY OF MAJOR RIVERS IN ORISSA STATE, INDIA

Geochemical analyses of surface waters from rivers flowing through Ori ssa State, India, indicated that trace element concentrations were ext remely variable and consistently higher than world river average. The Brahmani River was the most solute-rich river studied, followed by the Baitarani and Mahanadi Rivers. Although all three rivers drain simila r geology, the Brahmani River catchment is heavily industrialized, and water samples collected upstream and downstream from industries indic ated that anthropogenic activity directly influenced its chemical comp osition. Samples collected from several towns, in all three river syst ems, did not invariably show similar patterns, with various elements h aving higher dissolved concentrations upstream. Because the concentrat ion of total solids increased downstream, this implied that some compo nents of the sewage had effectively sequestered available elements fro m solution and converted them to particulate material. Although the im pact of pollution is clearly recognizable in water samples collected i n proximity to the anthropogenic source, there are only slight element al accumulations in the lower reaches of the Mahanadi River, with no a ccumulation in the Brahmani River. Apparently for these large rivers, discharged effluent becomes rapidly diluted, while complexation and se dimentation further removes trace elements from the water column. Howe ver, in the less voluminous Baitarani River, elementar enrichment near the river's mouth suggests that in this secondary river, where diluti on effects are less, the concerns over regional water quality may be m ore prevalent.