Comparative Assessment of Surface Soil Contamination Around Bellandur and Kengeri Lakes

The type and quantity of effluents and wastewater disposed of into highly polluted Bellandur and Kengeri lakes are different because of the nature and type of zone under the purview of two lakes. Study on the concentration of heavy metals in the lakebed sediments around both the lakes helps to identify the source of contamination and such a comparative study is almost non-existent. The present study comparatively assesses heavy metal contamination of surface soil around these lakes through grab sampling along with physical properties of soil to identify the presence of organic contents. Three locations of Kengeri Lake and four locations of Bellandur Lake were selected depending on the waste discharge locations. Samples of both the lakebed sediments indicate the presence of organic content. Both the lake sediments indicated heavy dosage of iron and chromium, in addition to nickel and zinc beyond the prescribed limits of FAO and WHO standards. The presence of mercury is also confirmed in both the contaminated lakebed sediments of both the lakes. However, the concentration of Fe is more compared to all heavy metals and the concentration of other heavy metals was found to be lower than permissible limits set by FAO as there was no defined source of heavy metal origin.