Assessment and occurrence of various heavy metals in surface water of Ganga river around Kolkata: a study for toxicity and ecological impact.

A study was conducted during November, 2005-October, 2006 to evaluate the surface water quality of river Ganga around Kolkata. The samples were analyzed for a number of physico-chemical parameters using standard laboratory procedures and giving prime thrust to determine the heavy metal concentrations (Fe, Mn, Cu, Zn, Pb, Cd, Cr, and Ni) of surface water at four different locations of the river Ganga around Kolkata from two points (middle of the river stream and a discharge point) at each location. Out of 96 samples analyzed, Fe, Mn, Cu, Zn, and Ni were detected in 71, 47, 38, 60, and 45 samples in the concentrations ranging from 0.013 to 5.49, 0.022 to 1.78, 0.003 to 0.033, 0.005 to 0.293, and 0.045 to 0.24 mg L(-1), respectively. Cd and Pb were detected in six and 21 samples in the range of 0.005 to 0.006 and 0.05 to 0.53 mg L(-1), respectively. But Cr was not detected in any of the samples analyzed. The metals exhibited no significant variation with respect to sampling locations as well as discharge points. However, the concentration of those metals varied with season, being higher in rainy and lower in winter season.

Impact assessment of pesticide residues in fish of Ganga river around Kolkata in West Bengal.

An investigation was conducted from 2001 to 2005 for determining the residual concentration of five pesticides, viz., total-HCH, total-DDT, total-Endosulfan, Dimethoate and Malathion in fish samples collected from various points of the river Ganga. Fish samples were analyzed for pesticide residues using standard laboratory procedures by GC method. It was found that total-HCH concentration remains above the MRL values for maximum number of times in comparison to four other pesticides. The pesticide contamination to fish may be due to indiscriminate discharge of polluted and untreated sewage-sludge to the river. The pesticide contents in some places are alarming. Thus proper care, maintenance, treatment and disposal of sewage water and sludge are most vital and should be the prime thrust for the nation.