DISTRIBUTION OF HEAVY METALS IN SURFACE SEDIMENTS OF THE LUANHE RIVER ESTUARY AND ECOLOGICAL RISK ASSESSMENT

Thirty-three surface sediment samples from the Luanhe River Estuary have been analyzed for heavy metals of Cu, Pb, Zn, Cr, Cd and Hg in order to reveal their spatial distribution and make evaluation of contamination. Higher heavy metal concentrations are found at the river mouth and southern areas covered by sandy silt or clayey silt. Compared with the data collected in 2007, the high value heavy metals zones of 2013 become closer to the estuary. The study of enrichment factors indicates that Cu, Zn and Cr, which are mainly derived from the natural weathering of rocks, are not enriched and Cd and Hg are partly enriched in minor to moderate amount under the influence of both the natural and the anthropogenic sources. Pb was mainly derived from the anthropogenic sources. Fluvial input and coastal discharge are the primarily sources of these heavy metals. Risk assessment shows a low degree of contamination and ecological risk in the region.