Composition, distribution and enrichment of trace metals in sediments from the muddy area off the southern Shandong Peninsula in the Northwestern South Yellow Sea of China since 10,000 years

We analyzed ten trace metals (Cu, Pb, Zn, Cr, Cd, Hg, As, Ni, V, Co and Ni) in sediments of the upper 14.98 m of core WHZK01 from the muddy area off the Shandong Peninsula, northwestern South Yellow Sea, to analyze their content, vertical distribution, and the enrichment status. Except for Hg and As, the other metals (Cu, Pb, Zn, Cr, Cd, Ni, V, Co and Ni) were mainly controlled by grain size. When the sediment particle size became smaller, the metal content reached a high level. Moreover, oxides and hydroxides of Al, Ti, Fe, and Mn also contributed to the metal enrichments due to their strong adsorption to the metals. Over the past four stages of 10-7 kyr BP, 7-4.5 kyr BP, 4.5-2.5 kyr BP, and 2.5 kyr BP to date, the metal values have shown a trend of increasing - fluctuating to high values - decreasing - re-increasing, respectively. However, since 4.5 kyr BP, Hg concentrations have been on an increasing trend, associated with the release of large amounts of contaminants into the environment from ancient human metal mining and smelting activities. As concentrations, despite the fluctuating changes, have remained relatively stable at high levels since 5.5 kyr BP, associated with their high background values.