Abstract

Wetlands are transition zones on earth that plays a major role in nutrient dynamics and governs the primary productivity. Bangalore and its urban conglomerates comprise of many man-made wetlands that were built for various hydrological purposes to serve the needs and water demand of the city. Bangalore wetlands have been experiencing anthropogenic stress especially due to the sustained inflow of sewage altering the chemical integrity of wetlands. The present study was carried out to evaluate seasonal variation in the physico-chemical parameters of water quality and to compute water quality index of Hebbal Lake, Bangalore. Water samples were collected from 4 sites and were analyzed for pH, Electrical conductivity, TDS, Dissolved oxygen, Nitrate, BOD, Total hardness, Ca, Mg, chlorides and alkalinity according to standard methods. Seasonal variations in water quality parameters were recorded, compared with standards and pollution status was studied using water quality index, Results showed that BOD, alkalinity (sample S1),TDS and EC were higher than prescribed limits by BIS standard. High levels of nutrients and organic load was seen in the inlet region compared to middle and outlets. Overall water quality index showed the lake falls under very poor category. The results revealed anthropogenic activity and entry of untreated sewage into the lake through inlet.

KEYWORD: Bangalore, Hebbal Lake, Physico-chemical parameters, Water quality index.