Spatial changes in water and heavy metal contamination in water and sediment of river Ganga in the river belt Haridwar to Kanpur.

ABSTRACT

Despite heavy investments and a number of government schemes, deterioration in water quality of river Ganga and its tributaries is an issue of serious concern. Among all the cities, thriving on Ganga, Kanpur is considered to add maximum pollution in the river. In the present study, water samples were collected seasonally from nine selected sites within the middle stretch of river Ganga from Haridwar to Kanpur. The velocity, temperature, pH, alkalinity, hardness, dissolved oxygen (DO), biological oxygen demand (BOD) and chemical oxygen demand (COD) were analyzed during winter (November-January), summer (March-June) and monsoon (July-September) season from November 2016 to September 2017 along with heavy metal analysis of water and sediment samples of the winter season. The levels of Cr, Cu, Cd and Pb were analyzed by atomic absorption spectrophotometer. Water quality was evaluated by water quality index (WQI) using BIS and WHO standards. The WQI values showed good water quality at Haridwar site (< 100) while it was very poor at other sites and Kanpur (> 100) which renders it highly unfit for human consumption and survival of some fish species because of low DO value (4.65 ± 1.08 mg L-1) and high values of pH (8.82 ± 0.10), alkalinity (187.88 ± 8.88 mg L-1), BOD (66.64 ± 2.19 mg L-1) and COD (240.00 ± 17.33 mg L-1). WQI showed highly unsuitable water quality at all sites except control site, of which S9 (Siddhanath Ghat) was highly polluted. Lead concentration was higher at Kannauj sites while high Cr was observed at Siddhanath Ghat (S9), Kanpur. The examined metals, such as Cr, Cu, and Pb, were far above the prescribed limits of various standards.