Distribution and source identification of trace metals in the sediment of Yellow River Estuary and the adjacent Laizhou Bay

Rapid economic development in the Yellow River basin has inevitably resulted in increase of pollution in the estuary, and concern for both the environment and protection against pollutants is increasing. Contents of trace metals (Cu, Pb Zn, Cr, Cd, As, Hg), Fe, Al, total organic carbon (TOC), and their granulometry were determined in surface sediment samples from the Yellow River estuary and its adjacent areas. Metal contents were significantly correlated each other. Clay, TOC and heavy metal contents showed similar distribution characteristics, with concentrations increased from the land to the sea. The distribution of grain size plays an important role in influencing the distribution of trace metals. Heavy metal concentrations showed a significant relationship with Fe and Al content, while most heavy metals were not enriched. These results were also confirmed by the analysis of enrichment factors and principal component analysis of the metals. The metal content of the Yellow River Estuary sediments was similar to the content observed 20 years ago, but the concentrations of most metals in Laizhou Bay decreased. The decrease in the carrying sediment of the Yellow River might be responsible for this pattern.