LOCALISED EFFECT OF ARTISANAL AND SMALL SCALE MINING OF LIMESTONE ON WATER QUALITY IN MEGHALAYA, INDIA

摘要

Artisanal and small scale mining (ASM) of limestone rocks in Sohra, Meghalaya has been going on for years. Mining and processing of limestone in this area are carried out mainly for production of calcined lime. Both quicklime and edible lime are produced at small scale level. Mining activity is the source of income and employment for a number of people of the area. However, the processes generate overburdens and lime waste materials that are disposed off in the nearby areas which pose some environmental problems including adverse effect on water. In this paper, we report the result of our study on limestone mining and processing and its effect on water quality of the area. Water samples were analysed from the vicinity of mining and processing area (S3) and also from its upstream (S1) and (S2) and downstream (S4) areas at Mawsmai village, Sohra, Meghalaya during pre-monsoon and post-monsoon seasons, 2013. The values of various physicochemical parameters studied show that water samples from S1 location are not polluted and all parameters were found within the permissible limits. However, water at S2 was found slightly affected by the localised activities during the post-monsoon. On contrary, the water in the vicinity of mining and processing area (S3) possessed elevated pH (10.1-10.8), EC (343.33-747.67 μs cm), IDS (183.33-260 mg/L), TH (126.67-261.33 mg/L), sulphate (304.17-687.50 mg/L) and calcium (44.30-100.08 mg/L) in both the seasons. pH, EC and sulphate values were found remarkably above the standard range of water quality at S3. Using Water Quality Index (WQI), the quality of water at different sites was classified. The highest WQI for both seasons was reported for S3 showing water unfit for human consumption.