Monitoring the self-purification capacity of the River Alaknanda stretch at Srinagar, Uttarakhand, India

摘要

After six months from Uttarakhand's biggest flood tragedy that took place at Kedamath, a rapid investigation was conducted to assess the water quality and purification capacity of flooded River Alaknanda. Representative water samples were collected from eight different sites selected along the river stretch and relevant physico-chemical parameters along with biological indicators (coliform and periphyton) were analysed to get effective results. The results indicated that all the studied parameters were under the permissible limits prescribed by World Health Organization (WHO) and Bureau of Indian Standards (BIS) except the coliform count, which ranged between 65 and 270/100 ml. The biochemical tests and staining tests marked the species of Lactobacillus, Bacillus, Clostridium, Streptococcus, Staphylococcus, Escherichia coli, Shigellas, Salmonella and Pseudomonas in the studied stretch of the Alaknanda. A high range of dissolved oxygen (DO, 8-9.8 mg/l) and a low range of biochemical oxygen demand (BOD, 1.2-2.8 mg/l) for the studied river stretch showed its good purification potential. Moreover, algae like Oscillatoria, Euglena, Chlamydomonas, Navicula, Nitzschia, Fragillaria, Amphora and Synedra which are considered as good self-purification agents of water bodies, were dominant in organically polluted sites. The periphyton density was recorded as a maximum of 19.9 × 10~(10)/m~2 in the month of February at the S4 site and the periphyton biofilm thickness was recorded as a maximum of 3.8 mm at the S4 site in April. Mostly, the sites having high BOD, that is, S4 and S6, harboured a high level of bacterial and algal species representing them as a good indicator of organic pollution. The study suggests that the water of the studied stretch of the River Alaknanda is not compatible for drinking purposes without treatment as the presence of various pathogenic agents has been observed that may enhance the chances of various diseases and infections to local people of the region.