Necessity of Combining Geochemical and Geomorphic Processes Addressing Pollution Problems in the Fluvial System of the Ganga Plain, India

Abstract

The Ganga Plain is one of the largest alluvial plains of the earth. It is a huge natural laboratory to test a number of hypotheses on sedimentary and geochemical processes of past and present. For several decades, the indiscrimate use of the drainage basin of Ganga Plain for the disposal of domestic and industrial wastes has adversely effected the quality of water, sediments and agricultural soils. The mobilization of various metal pollutants in sediments of this highly dynamic fluvial system is a complex process in which sediment-water movement is extremely variable due to their continuous input from the Himalaya and southern India under changing hydrological conditions (e.g. Monsoon). The present study was aimed at quantifying the level of geogenic and anthropogenic metal pollutants (A1203, Cd, Co, Cr, Cu, Fe203, Ni, Pb, Sn, and Zn) in different hydraulic conditions (e.g. Monsoon), and their dispersion and mobilization processes in various eco-compartments (sediment, water and soils) of the fluvial system of the Ganga Plain. This plain has different geomorphic surfaces and features whose role and control on dispersion patterns of metal pollutants in sediments and soils has been demonstrated. In sediments, about 90 % of the contents of Cd, Cr and Sn, 50-75 % of Cu, Zn and C-org, and 25 % of Co, Ni and Pb; and in soils about 90 % of the contents of Cr and Sn, about 75 % of Cd, and about 25 % of C-org, Cu, Ni, Zn respectively are of anthropogenic origin. Surface and pore water of this