Assessment of seasonal variation of heavy metal pollution and health risk in surface sediments at the Karnaphuli River confluences of Chattogram, Bangladesh

Abstract The sessional variation of heavy metals pollution and potential health risks in sediments to local people were studied using a flame atomic absorption spectroscopy (FAAS). Ten (10) different khals that serve as the natural drainage of Chittagong City were chosen for collecting the surface sediments samples from the confluence of the Karnaphuli River. The mean concentration of Cu, Cr, Cd, Pb, Ni, Mn, As and Zn in sediments samples were 38.83, 46.92, 2.18, 42.98, 43.39, 63.04, 1.34 and 91.93 mg kg − 1 respectively for the wet session, while the respective values in dry season were found 51.12, 59.23, 2.52, 61.04, 49.66, 58.54, 2.21 and 104.44 mg kg − 1 . The enrichment factor (EF), contamination factor (CF), modified contamination degree (m C d ), degree of contamination ( C d ), geoaccumulation index ( I geo ), potential ecological index ( PERI ) and nemerow pollution index (P N ) were calculated to estimate the pollution level of the study areas. Potential carcinogenic and non-carcinogenic health risks through dermal contact were also calculated using respective mean values of heavy metals. Statistical analyses were applied in order to findout the establish the association and source of heavy metals between pollutants in river sediments. The results showed that concentration of heavy metals was higher in the dry season than in the wet season at most of the locations. The obtained comprehensive data for toxic heavy metals in the surface sediment of the Karnafuly River along the Chittagong City Corporation may help the policy maker to take effective legislation for monitoring and protecting the ecological risks of the Karnafuli River.