Contamination, toxicity and speciation of heavy metals in an industrialized urban river: Implications for the dispersal of heavy metals

•Contamination, toxicity and speciation of heavy metals in Dongbao River are examined.•The sediment is seriously contaminated with Cr, Cu and Ni which pose acute toxicity.•Dominance of non-residual fractions indicates high mobility of Cd, Cu, Ni and Zn.•The dispersal of heavy metals causes contamination in the non-industrialized areas.•Given the vertical profiles, management efforts on the point sources are inadequate.

Urban rivers are often utilized by the local residents as water source, but they can be polluted by heavy metals due to industrialization. Here, the concentrations, toxicity, speciation and vertical profiles of heavy metals in sediment were examined to evaluate their impact, dispersal and temporal variation in Dongbao River. Results showed that the sediment in the industrialized areas was seriously contaminated with Cr, Cu and Ni which posed acute toxicity. Heavy metals, except Cr and Pb, were mainly associated with non-residual fractions, indicating their high mobility and bioavailability. The non-industrialized areas were also seriously contaminated, suggesting the dispersal of heavy metals along the river. The surface sediment could be more contaminated than the deep sediment, indicating the recent pollution events. Overall, when the point sources are not properly regulated, intense industrialization can cause both serious contamination and dispersal of heavy metals, which have far-reaching consequences in public health and environment.