当前世界环境

Various physico- chemical characteristics of the river Ganga in Varanasi were studied in the Oct 2006 to Nov 2007. Ecological parameters like dissolved oxygen(DO), pH, nitrate(NO3-), PO4³- and bacterial population were analyzed and compared with standard permissible limits to asses the best designated use of the river water for various purposes. Study revealed that the water quality at Varanasi was not safe for human use. Result shows that Fecal coliform (20.9×10³/100ml), Fecal streptococci (93/100ml), Total bacterial density (1.43×10³/L), Total coliform (25.4×10³/100ml) Escherichia coli (6.9×10³/100ml) and Clostridium perfringens (396/100ml ) were substantially high and much beyond the permissible limit of ISI and WHO. The river in Varanasi upstream was of better quality whereas the Varanasi downstream stretch was polluted as indicated by very low DO and high bacterial density. Some pathogenic bacteria Actinomyces sp., Aerobacter aerogenes, A. Cloacae, Micrococcus sp., Salmonella sp., Staphylococcus aureus, Bacillus sp. and Shigella sp. that indicate the higher level of fecal contamination in water. These untreated water sources are used for drinking and domestic purposes and pose a serious threat to the health of the consumers and therefore calls for urgent intervention by government.