Risk assessment of toxic metals in marine sediments from the Arctic Ocean using a modified BCR sequential extraction...

Surface sediment samples were collected from the Pacific sector of the Arctic Ocean during the 6^th Chinese National Arctic Research Expedition (CHINARE), 2014. Concentrations and extractabilities of six toxic metals (Cd, Cr, Cu, Ni, Pb, and Zn) were determined using a modified sequential extraction procedure as described by the European Community Bureau of Reference (BCR). A new analytical hierarchy approach to risk assessment, involving sediment quality guidelines and risk-assessment codes, is described for metals in marine sediments from the Arctic Ocean. Results indicate a mobility order of Pb > Cd > Cu > Zn > Ni > Cr with mean liable fraction (F1+F2+F3) being 83.0%, 81.6%, 62.0%, 47.1%, 42.1%, and 15.6%, respectively. Ni presents the most serious ecological risk in the study area, with most samples (93.9%) indicating medium risk, followed by Cu (54.5%) and Zn (27.3%). For Ni and Zn, there are also samples showing high ecological risk (Ni at site NB02, northern Bering Sea; Zn at R07, northern Chukchi Sea). The ecological risk for Cr indicates low ecological risk (93.9%) and some medium risk (6.1%). All Cd assessments indicate low ecological risk, while most Pb assessments indicate zero (33.3%) to low risk. The new ecological risk assessment method improves on assessments based on metal mobility or concentration alone.