Environmental Geochemistry of Indian River Basins-A Review

Based on extensive observations, the sediment and the chemical load- both quantity and quality - have been computed for the Indian sub continent. Indian rivers carry total dissolved solids of 159 ppm, which is about 25% more than the world average river water. Indian rivers are also relatively enriched in Na and Cl. They also carry a sediment load of about 1.4 billion tonnes/yr representing 10% of the global sediment flux. The northern rivers carry dominantly illite-kaolinite-chlorite in suspension while the southern rivers carry high exchange capacity clays. The sediment chemistry is comparable to world surface rocks, with corrections for the mobile elements. Heavy metals occur predominantly in the chemically extractable sinks within the river sediments. Limited studies on base metal mining areas in Khetri and Zawar indicated contamination of soil, plants and water in that area.