Theme 3-14-Groundwater quality deterioration due to clay mining industry in a midland region of Kerala

Abstract

Groundwater represents a significant and in many places predominant proportion of the drinking water source. In Kerala State, open dug wells are the sole source of drinking water especially in rural areas where surface water based protected water supply systems are scanty. The availability of this precious resource is diminishing in recent past not only due to over exploitation but also due to pollution arising from different origin. Indiscriminate disposal of sewage and solid wastes on lands coupled with agricultural and industrial activities pose great threat to domestic wells. Groundwater quality deterioration due to industrial activities needs special mention as industries discharge enormous quantities of untreated or partially treated wastes containing toxic chemicals into the environment which ultimately reaches subsurface water sources. A study conducted to assess the quality of selected wells around a clay mining industry in Kannur, Kerala revealed that over 61% of the observation wells has been polluted due to the presence of high level of sulphate or chloride and become non-potable. The wells located within one km distance are more affected than the wells beyond. The predominant pollutant is observed to be sulphate with a maximum recorded concentration of 1875 mg/l in the well water. The mine discharge effluent was characterised by high acidity with pH value as low as 2.4 and of sulphate as high as 2860 mg/l. The sulphur bearing overburden materials of the mining site especially iron pyrite was observed to be the major cause of the pollution. Few wells located east and western side of the mining area were observed to have the influence of salinity intrusion also.

The study deals with the impact of indiscriminate discharge of mine effluents on the groundwater quality especially in open dug wells around clay mining industry at Madayi, Kannur District of Kerala. The nature and extent of pollution and , the temporal variations are discussed. An attempt was also made to use the stable isotope technique using 34S/32S ratio to identify the source of sulphate in this area.