CS(AR)-8/98-99 : Ground water quality in Greater Guwahati, Assam with reference to trace elements

Abstract

Ground water is one of the most important sources of drinking water in India. Degradation of ground water quality due to heavy metals has received considerable attention during recent years. Pollutants are being added to the ground water system through human activities and natural processes. Solid waste from industrial units is being dumped near the factories. which is subjected to reaction with percolating rain water and reaches the ground water level. The percolating water picks up a large number of heavy metals and reaches the aquifer system and contaminates the ground water. The quality of ground water is dependent on the geologic, climatic, environmental, biological and other anthropogenic activities. Several reports are available which indicate that samples collected from shallow aquifers shows higher concentration of heavy metals than those from deeper aquifers.

In the present report, ground water quality of Greater Guwahati is presented with reference to trace element contamination. The various elements analysed include Cu, Co, Cd, Fe, Zn and Pb. The trace element analysis of ground water samples has revealed that the concentration of iron in ground water is much higher than the tolerance limit prescribed for drinking water. The maximum concentration recorded was 3.58 mg/L. The presence of iron above acceptable limit in drinking water often imparts alien taste and inky flavour. It can also discolour cloths, plumbing fixtures and cause scaling which encrusts pipes. Excessive concentration of iron may promote bacterial activities in pipes and cause objectionable odours and red-rod disease in water.