IMPACT OF TRANS-BOUNDARY COAL MINES ON WATER QUALITY OF RECEIVING STREAMS IN NORTH-EASTERN BANGLADESH

Abstract

In the north-eastern part of Bangladesh, direct discharge of Acid Mine Drainage (AMD) from upstream Khashi hill areas of Meghalaya into trans-boundary Rivers causes huge losses of fish and crops. The purpose of this study is to investigate the impact of coal mines on water quality on the basis of physico-chemical parameters, such as temperature, pH, electrical conductivity, dissolved oxygen, biological oxygen demand, chemical oxygen demand, total dissolved solids, and heavy metals viz. Fe, Pb, Cr and Cd. For this purpose, a total of 15 samples were collected with 3 replications from 5 different locations of Jadukata River. The mean values of the analyzed parameters for 5 different sampling sites ranged: pH: 6.63-8.47; temperature: 25.77-26.8 °C; EC 344.51-383.50 μS cm-1; DO: 7.60-8.30 mg l-1; TDS 337.33-454.33 ppm; BOD: 0.70-1.93 mg l-1; COD: 1.20-2.30 mg l-1; Fe: 0.69-0.86 mg l-1; Pb: 0.05-0.07 mg l-1; Cr: 0.04-0.06 mg l-1. Analyzed results show that, most of the values of the considered parameters were higher at Lakmachara point, which is the nearest site to the Indian border and low at Rajargao, the farthest from the border. Almost all the values of Pb and Cr in different sampling points were higher than their permissible limits for drinking but, the values were within limit for irrigation activities. Other parameters were found within the permissible limit for drinking and irrigation usage. The gradual descending variations of the analyzed parameters from downstream to upstream were mostly due to the effect of AMD, which was mixed with the water of Jadukata River. Leaching of heavy metals near Khashi hill areas of Meghalaya at the upstream of Jadukata River are the major causes of contamination of the Jadukata River.