Metals in water, suspended solids and sediments of the Amur River Estuary

The distribution of dissolved and suspended forms of Fe, Mn, Zn, Cu, Pb, Cd and Ni and their concentrations in sediments were studied along a salinity gradient in the Amur river estuary Down reach of Amur River is characterized by background concentrations of metals in suspended solids and low content of dissolved forms of metals. Elevated dissolved Fe is the only exception. The dissolved metals distribution along the salinity gradient showed non-linear decrease for Fe, quasi-linear decrease for Cu and Ni, scattered decrease for Pb, and just scattering for Zn. Mn and Cd have shown non-linear increases in the water with salinity 10-25%. due to release from sediments and internal cycling. Desorption could be an additional source. The change of metal concentrations in the suspended matter is controlled mainly by the ratio of terrigenous material enriched in Al, Fe and Ni, and marine biogenic particles enriched in Cu, Mn and Cd.