ASSESSMENT OF HEAVY METAL POLLUTION AND BACTERIAL HEAVY METAL RESISTANCE IN THE SEDIMENTS OF VATTAKAYAL LAKE SYSTEM, NEAR CHAVARA INDUSTRIAL AREA, KOLLAM, KERALAP.M. Koshy, Rinoy Varghese, Subin K. Jose, C.B. Mayarani and A.P. Thomas
The Industrial Revolution brought about an increased production and discharge of both xenobiotics and natural chemical substances which usually end up in the sediments of water bodies. The tolerance of bacteria to heavy metals has been proposed as an indicator of the potential toxicity of heavy metals to other forms of biota. The present study was aimed to evaluate the extent to which the industrial waste influences the deterioration of sediment quality in a lake system. Analysis was carried out for the heavy metal content (Fe, Zn, Cr, Ni, Pb and Cu) and the multiple heavy metal tolerance patterns of bacterial strains in the sediments of Vattakayal lake system near Chavara industrial area, Kollam, Kerala. The study revealed that the sediments were contaminated with heavy metals in the sequence of Fe>Cr> Zn> Ni> Cu> Pb. The heavy metal contents in stations near to the industrial area were found higher than the other stations. Fe, Cr and Zn were found in significantly higher levels in station 6. The results were also interpreted using Geographic Information System (GIS) tools. Metal resistance studies of the bacterial isolates showed that about 57% of the isolates showed comparatively high tolerance (≥300µg/mL) to lead, zinc and copper. Tolerance to Ni was rather low (<115µg/mL). Resistance to cadmium and chromium were in between 95µg/mL - 300µg/mL and 100µg/mL - 250 µg/mL respectively. It was observed that the concentration of heavy metals was higher during pre-monsoon compared to the monsoon season and the deterioration of the quality of sediment increased with decrease in distance from the industrial area.
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