Abstract:Literature lacked in providing a comprehensive research on heavy metal detection in aquatic, biological and sedimentary states of rivers. The present study was imparted with all these three components of the river. Heavy metal toxicity or pollution index was used as a tool for ecological risk assessment by considering the single state studies conducted by many researchers. An intensive ecological risk assessment model was constructed and heavy metals were indicated as a serious threat to the environment. The model was applied to determining five toxic heavy metals in three states of the Songhua River. According to the ecological risk index, heavy metal pollution in three phases was categorized as aquatic>biological>sedimentary, while the overall descending order of heavy metal ecological risk index was as Cd>Hg>As>Pb>Cr. Cd and Hg were selected as the priority pollutants of Songhua River.

Key words: comprehensive ecological risk assessment; priority pollutants selection; heavy metal; Songhua River