Physico-Chemical characteristics of drain-water of open cast coal mining area in the Ledo-Margherita range of Assam

Coal mine drainage is a major problem in coal mining areas. It may adversely affect the water-bodies in and around mining areas. Oxidation of pyrites, from coal seams and overburdens, in presence of air and water leads to very low pH and results in sulphate and heavy and rare earth metals dissolved into the water. In the present study, Physico-Chemical Characteristics of water of drains carrying mine-waters in Ledo and Tirap open cast coal mining areas have been investigated. Water samples were analysed for pH, Electrical Conductivity (EC), hardness SO₄^2-, NO₃⁻, dissolved oxygen (DO), Fe²⁺, Cr, Pb, Ni and Zn. The results indicate highly acidic condition of the drain-water with low DO, high EC, high hardness and higher concentrations of SO₄^2-, Fe²⁺ and Pb.