Heavy metal pollution in surface water and sediment: A preliminary assessment of an urban river in a developing country

•We investigated total and speciation of heavy metals in sediments.•Elevated levels of metals in water and sediments were observed.•Cd and Pb were in non-residual while Cr, Ni, Cu and As in the residual phase.•Metal effects on sediment were achieved by using CF, Igeo, PLI and EF.•Cd and Pb confirmed the seriousness in the aquatic environment.

The concentration and chemical fractionation of globally alarming six heavy metals (Cr, Ni, Cu, As, Cd and Pb) were measured in surface water and sediment of an urban river in Bangladesh. The decreasing trend of metals were observed in water as Cr > Cu > As > Ni > Pb > Cd and in sediment as Cr > Ni > Cu > Pb > As > Cd. The level of studied metals exceeded the safe limits of drinking water, indicated that water from this river is not safe for drinking and/or cooking purposes. However, the investigated metals showed low mobility except for Cd and Pb which could pose a severe threat to the aquatic environment. Contamination factor (CF) and geoaccumulation index (Igeo) demonstrated that most of the sediment samples were moderately to heavily contaminated by Cr, As, Cd and Pb. The pollution load index (PLI) values were above one (>1) indicates progressive deterioration of the sediment quality. The extent of pollution by heavy metals in the river Korotoa implies that the condition is much frightening to the biota and inhabitants in the vicinity of the river as well.

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