Geochemistry of zinc in the sediments of the western continental shelf and slope of India

Abstract

The bulk geochemistry of zinc in the sediments of the western continental shelf and slope of India and also the partition geochemistry of the sediments of the shelf and slope regions between Ratnagiri and Mangalore have been studied. The studies indicated that (1) the concentration of zinc varies very widely in these sediments; (2) the concentrations of zinc exhibit a decreasing trend away from the coast and an increasing trend in the slope region; (3) zinc co-varies with Al, Fe, Mn and organic carbon in these sediments and bears a strong inverse relationship with CaCO3 content. The partition studies of the sediments of the shelf and slope regions between Ratnagiri and Mangalore have indicated that (1) zinc has both a lithogenous and non-lithogenous components in these sediments; (2) the percentage contributions made by the lithogenous-non lithogenous component to the concentrations of zinc in the bulk samples vary; (3) the inter-relationships of zinc worked out with other elements in the lithogenous component of the sediments separately for inner shelf, outer shelf and slope have indicated that in the inner shelf it co-varies with all the elements except CaCO3, in the outer shelf and slope regions with iron and organic carbon only, and bears a strong negative correlation with manganese; (4) inter-relationships of zinc is worked out with other elements. The type of association zinc has exhibited with other elements is confirmed by the R-mode factor analysis carried out for the sediments of the region between Ratnagiri and Cochin. Further, the association of zinc with organic carbon all over the shelf and slope regions is found to be similar to that reported from upwelling regions of other areas