Textural and heavy metal distribution in sediments of Mahanadi estuary, East coast of India

Abstract

Surface sediment samples from the Mahanadi estuarine region were collected during May, 2008 to April, 2010 in three different seasons (pre-monsoon, post-monsoon and summer) annually. Present study focuses on the levels of Pb, Cd, Hg, texture pattern and organic carbon in order to assess the extent of environmental pollution. Concentration data were processed using correlation analysis. Contamination of sediments was assessed on the basis of contamination factor (CF), geo-accumulation index (I-geo) and pollution load index (PLI). Average concentration of Pb, Cd and Hg were 23.88 +/- 8.88 mu g/g, 1.45 +/- 0.14 mu g/g 0.107 +/- 0.070 mu g/g in 2008-09 and 23.89 +/- 7.27 mu g/g, 0.65 +/- 0.50 mu g/g, 0.102 +/- 0.058 mu g/g in 2009-10 respectively. Texture pattern found to be sand dominated averaging over 96.00% in both the years followed by silt and clay fraction. Results of Pearson correlation matrix showed a positive correlation of grain size and organic carbon with concentration of Cd and Pb suggesting the influence of fine fraction in their incorporation into the sediments. Results of geo-accumulation index indicated that the sediments were uncontaminated with Hg, uncontaminated to moderately contaminated with Pb and moderately contaminated with Cd in the estuarine region.