Elemental Composition of Damodar River Sediments - A Tributary of the Lower Ganga, India

Bed, suspended and core sediments collected from the entire region of the basin were analysed to determine the elemental chemistry of the sediments of the Damodar river basin. The analytical results show that bulk sediment chemistry consists mostly (>75%) of five elements, Si, Al, K, Fe and Na. Mean composition has indicated that the Damodar sediments are depleted in Ca, Mg and heavy metals and enriched in Si and K as compared to the other Indian river basins. The concentrations of heavy metals in the suspended sediments are significantly higher than the bed sediments. In general, heavy metal concentration increases towards the finer size fractions. The depth variation of heavy metals in the core sediments shows no specific trend. Speciation studies show that the lithogenic phase is the major sink for heavy metals. Fe-Mn oxide and organic fractions are the major nonlithogenic phases and Zn is the major constituent of the nonlithogenic phase. Geoaccumulation indices calculated for Fe, Mn, Cu and Zn indicate that Damodar sediments are not polluted with respect to these metals.