Spatial distribution, fractionation, toxicity and risk assessment of surface sediments from the Baiyangdian Lake in northern China

Abstract

The pollution of Baiyangdian Lake (BYDL) has been of concern since the Xiongan New Area was established. To conduct ecological restoration of BYDL, the heavy metals (HMs) levels in sediments were assessed. Specifically, Surface sediments (0–10 cm) samples in BYDL were analyzed for Cd, Cr, Cu, Ni, Pb and Zn in October 2016 to evaluate the risk posed by trace metals, as well as their bioavailability and toxicity. The results demonstrated that HMs showed high pollution and risk levels in most sample sites as a result of Cd and Pb. Metals speciation analysis demonstrated that Cd, Cu, Pb and Zn were dominated by non-residual fractions that originated from anthropogenic sources and presented higher bioavailability. The risk assessment code indicated that Cd poses a medium level biological risk in BYDL, which reached 10.25% and 29.38%. The bioavailable metals index showed a strong correlation with acute toxicity (R2 = 0.704), indicating bioavailable metals are an important reason for sediment acute toxicity. Canonical correspondence analysis demonstrated that HMs have a coercive effect on the distribution of benthic invertebrates. Overall, the results indicate that HMs pollution should be considered during the development of strategies for ecological restoration in BYDL.