Spatial distribution of heavy metals in surface sediments from the Ganges River basin, Bangladesh

Abstract

The spatial distribution and source of heavy metals (Ba, Cr, Ni, Pb, V, As, Zn, and Cu) in surface sediments of the Ganges River basin, Bangladesh, were investigated using the geo-accumulation index (Igeo), contamination factor (CF), and pollution load index (PLI). The sequences of mean concentrations of the studied heavy metals are in decreasing order as follows: Ba > V > Cr > Zn > Pb > Ni > As > Cu > Hg. Sediments in the Ganges River basin are characterized by low to moderate Igeo values for Ni, Zn, Pb, and V, while high values for Ba, As, Cu, and Cr, indicating low to moderate/high contamination of the river sediments. The mean CF load in the sediments shows that Ba is highly enriched, having moderate enrichment of As, Cu, and Cr, and relatively low enrichment of Pb, V, Zn, and Ni for the lower river basin reflecting high to moderate degree of metal pollution of the sediments. The PLI values range from 0.11 to 5.89 (average 0.88 ± 1.28) and 0.41 to 8.79 (average 2.13 ± 1.81) for the upper and lower Ganges River basin, respectively, which suggests that the enhanced metal pollution in the latter site is due to the threat of progressive industrialization. The principal component analysis (PCA) and hierarchical clustering (CA) records imply that the sediment samples are primarily polluted by As, Cu, Cr, and Ni resulting from anthropogenic sources. The mean Igeo and PLI values further reflecting high level of metal contamination in the lower Ganges River basin and relatively low level of contamination in the upper basin.