Site-wise Mercury Levels in Ulhas River Estuary and Thane Creek near Mumbai, India and its Relation to Water Parameters

Ulhas river estuary (73°14′E, 19°14′N to 72°54′E, 19°17′N) and Thane creek (72°55′E, 19°N to 73°E, 19°15′N) near Mumbai, India are highly polluted owing to the heavy load of industrial pollutants and sewage discharge. The traditional fisher-folk living along the banks of Ulhas river estuary and Thane Creek rely on these contaminated fish for their daily sustenance, thereby being exposed to heavy mercury pollution for several years. However, little attention has been given to the levels of mercury in water, its intake and exposure to those populations. In the present study, mercury levels in the waters of Ulhas river estuary and Thane creek has been analysed and its relation with other physicochemical parameters have been studied. Mercury level was maximum in Wehele station and Alimgarh station with an average of 8.57 ng/ml and minimum at Diwe-Kewni station with 2.6 ng/ml. Vittawa and Airoli stations along Thane creek showed moderate levels with an average of 5.71 ng/ml. The reference site, Khadavli had Hg below the level of detection in the water samples. Study on Hg levels in water showed proximity to the source of discharge to be the prime factor for its elevated levels. Mercury in water depicted positive correlations with temperature and BOD and negative correlations with pH, salinity, hardness and DO.