Assessment of eco-environmental geochemistry of heavy metals pollution of the river Gandak, a major tributary of the river Ganga in Northern India.

This study includes a seasonal analysis of sediment contamination of the River Gandak by heavy metals. It passes through the many small, medium and big cities of Uttar Pradesh and Bihar in Indian Territory. To explore the geochemical condition of the streambed sediment of the river, seven heavy metals, namely Co, Cu, Cr, Ni, Cd, Zn and Pb were analyzed. The newly deposited river bed sediment tests gathered on a seasonal basis from five stations for the years 2013-14 and 2014-15. Level of heavy metals in the sediments of the river was measured in the range between 10.54-16.78mg/kg for Co, 6.78-23.97mg/kg for Cu, 16.56-23.17mg/kg forCr, 9.71-18.11mg/kg for Ni, 0.364-1.068mg/kg forCd), 30.54-51.09mg/kg for Zn, 12.21-17.01mg/kg for Pb. Anthropogenic addition of heavy metals into the stream was controlled by utilizing metal Contamination Factor. Geo-accumulation values were found between (0-1) which indicates that sediment was uncontaminated to moderately contaminated, and can adversely influence the freshwater ecosystem of the river. A Good correlation was noted between Co, Zn, Pb, Ni, and Cu. Cluster analysis demonstrated three cluster groups of sites, which indicate that the metals originate from the same source mainly due to natural weathering of rocks, atmospheric deposition, human settlement and agriculture activity and is additionally confirmed by correlation analysis. However, on the basis of contamination indicators, it was found that the stream bed sediment is slightly contaminated with toxic metals. The conditions may harmful in the future because of the fast population growth in the river basin which might bring about irreparable biological harm in the long haul. [ABSTRACT FROM AUTHOR]