Application of 210Po isotope dating for chronological assessment of organochlorine pesticides in estuarine sediment

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.