The total content and chemical speciation of Cd, Cr, Cu, Ni, Pb, and Zn in seven short cores sampled from the Yitong River from Changchun City were analyzed to assess the pollution levels and potential ecological risks of heavy metals in the sediments. The results demonstrated that the total contents of Cd, Cr, Cu, Ni, Pb, and Zn in sediments were 0.10-1.18, 23.57-66.35, 11.27-43.95, 10.78-29.82, 15.02-60.81, and 54.27-175.83 mg·kg-1, respectively. The acid-soluble fraction of Cd varied from 42.1% to 51.28%, whereas Cr, Ni, and Zn were mainly found in the residual fraction; their mass fractions were 63.54%-79.91%, 35.16%-53.75%, and 27.55%-57.55%, respectively. The vertical results of pollution degree and ecological risk assessment indicated that the studied sediment was polluted by Cd, Cu, Pb, and Zn, and the ecological risk of Cd was the highest, followed by Zn and Cu. Each group of metals in each core showed a similar vertical variation, and the ecological risk of metals in sediment of 4-8 cm depth was relatively high. Cd, Zn, and Pb in the sediments of Yitong River were mainly from industrial pollution and municipal sewage discharge, and Cu could be attributed to both natural processes and human activities, whereas Cr and Ni may be attributed to natural processes.
Keywords: Yitong River; heavy metal; risk assessment; sediments; sequential extraction.