Heavy metal contamination and risk characterisation in sediment of an urban riverine system in Bangladesh

Metal contamination in river sediment can cause environmental and human health hazards. The present study was conducted in sediments of Louhajong River, Bangladesh to determine the contents of six heavy metals, their spatial distribution, ecological risks, sources of metals and health hazards through several exposure pathways. The mean concentration of Ni, Cd, Cr, As, Pb and Cu in sediments were 12.35, 0.60, 14.14, 11.69, 8.91 and 25.28 mg/kg, respectively. The mean content of Cd and As was higher than the threshold effect level whereas As and Cu content was higher than the toxicity reference value indicating sediment pollution by these metals. Potential ecological risks (203.82) and Nemerow pollution index (5.68) showed moderate and the highest contamination in sediment. The mean PEL quotient (1.58) and mean ERM quotient (0.64) indicated medium-high contamination based on sediment quality guidelines. The PCA indicated that the Kaiser-Meyer-Olkin Measure of Sampling Adequacy value was 0.61 and Pb, As, Cu and Cr were derived from anthropogenic sources in sediment. The total hazard index and cancer risks values for adults (HI: 3.20E+00, CR: 1.26E-03) and children (HI: 2.08E+01, CR: 8.18E-03) were higher than the standard limit (HI > 1, CR> 1.0E-04) resulting potential health hazards.