Abstract
In recent years there has been growing concern all over the globe about marine pollution due to persistent organic pollutants. Sediments, which is an important component of marine environment can serve as sorbent or concentrator for these pollutants. In this study, estimation of sedimentation rate using 210Po dating was carried out to study the depth profile of accumulated OCPs in sediments of Thane Creek Mumbai, India. The creek is a triangular mass of brackish water receiving huge municipal and industrial sewage inputs. Spatial distribution of OCPs was assessed in surface grab sediments and depth profiles of HCH and DDT were obtained in different cores. Radiological dating was performed by estimating the 210Po activity by alpha spectrometry, whereas the OCPs determination was carried out using gas chromatography.
The total HCH concentration in the surface sediment samples was in the range of 5.6–13.3 ng/g while total DDT concentration in the surface sediment samples was in the range of 3.2–5.5 ng/g. DDT and γ-HCH were the dominant OCPs in sediments from the creek. The sedimentation rate was determined using 210Po activity measurement in different cores of the sediment and was found to be 0.67 cm/y on average. It was observed that the sediments were highly contaminated during the period of 1970–80 just after the green revolution in India. Total DDT was highest in the 1974–1978 layers of the sediments. Total HCH was highest in the 1972–1976 layers at all the locations.