The tannery industry mushrooming in North India has converted the Ganga River into a dumping ground. The tanning industry discharges different types of waste into the environment, primarily in the form of liquid effluents containing organic matters, chromium, sulphide ammonium and other salts. As per an estimate, about 80-90% of the tanneries use chromium as a tanning agent. Of this, the hides take up only 50-70%, while the rest is discharged as effluent. Pollution becomes acute when tanneries are concentrated in clusters in small area like Kanpur. Consequently, the Leather-tanning sector is included in the Red category of industries due to the potential adverse environmental impact caused by tannery wastes. The Government of India (GOI) has numerous laws in place that affect the leather industry. Tanneries in India are required to comply with the regulations of the Central Pollution Control Boards and concerned State Pollution Control Boards. In 1996, the Supreme Court of India ordered the closure of all tanneries that had not set up pollution control systems. Using government subsidies, the tanneries have built numerous Common Effluent Treatment Plants (CETPs) to treat the toxic wastewater from tanneries. Despite this initiative, many of the pollution problems are still unresolved. The major components of the tannery effluents are the toxic trace metals (1). Several analyses reveal high concentrations of chromium even in supposedly treated effluents. The majority of chemicals discharged into aquatic system eventually end up in sediments that may act as a sink of pollution as well as a source of pollution. Sediments are ecologically important components of the aquatic habitat which play a significant role in maintaining the trophic status of any water body (2). Thus, study of sediment helps in the understanding of pollution effect as the residence time of pollutants in sediment of impacted area is long.
As reported earlier (3), that highly polluted sediments are adversely affecting the ecological functioning of rivers due to heavy metal mobilization from urban areas into biosphere. Distribution of heavy metals in sediments of the river Ganga and its tributaries have been carried out by several workers (4-11). Monitoring of Ganga River from Rishikesh to Varanasi indicated that Kannauj to Kanpur and Varanasi are the most polluted stretches of the river Ganga (12-13). Analysis of upstream and down stream water and sediment revealed a 10-fold increase in chromium level in the sediment at down stream Jajmau area of Kanpur showing unchecked release of untreated tannery effluent (1). The present study is, therefore, focused on the sediment quality assessment of samples collected from up and down stream of the Ganga River at Kanpur in order to find current status of pollutants discharged from the mushrooming tannery industries of the city and other sources. Chemical criteria provide a benchmark from which to evaluate the significance of contaminant concentration. The sediments from the two sampling areas were further evaluated for the release of trace metals in aqueous elutriates and their gross toxic effects using seed germination bioassay.
MATERIALS AND METHODS
The locations of sampling stations are shown in Fig. 1. Two sampling areas were selected; sampling area-1 was up stream at Bithoor village from where river Ganga enters towards Kanpur City and sampling area-2 was down stream at Jajmau which is situated at the exit point of river Ganga from Kanpur city area. The sediment samples were collected from six...