Behavior of trace metals in the sediment pore waters of intertidal mudflats of a tropical wetland

Authors

  • Kai-Tung Yu,

    1. Centre for Coastal Pollution and Conservation, Department of Biology and Chemistry, City University of Hong Kong, Hong Kong, People's Republic of China
    Search for more papers by this author
  • Michael Hon-wah Lam,

    Corresponding author
    1. Centre for Coastal Pollution and Conservation, Department of Biology and Chemistry, City University of Hong Kong, Hong Kong, People's Republic of China
    • Centre for Coastal Pollution and Conservation, Department of Biology and Chemistry, City University of Hong Kong, Hong Kong, People's Republic of China
    Search for more papers by this author
  • Yu-Fong Yen,

    1. Department of Chemistry, Hong Kong University of Science and Technology, Hong Kong, People's Republic of China
    Search for more papers by this author
  • Amy P.K. Leung

    1. Department of Chemistry, Hong Kong University of Science and Technology, Hong Kong, People's Republic of China
    Search for more papers by this author

Abstract

Vrtical profiles ofdissolvedCd, Cr, Cu, Pb, Zn, Fe, and Mn in the sediment pore waters of the intertidal mudflats of the Mai Po and Inner Deep Bay Ramsar Site of Hong Kong, People's Republic of China, were measured using the polyacrylamide gel diffusive equilibration thin film (DET) technique. The ranges of concentrations of dissolved Cd, Cr, Cu, Pb, Zn, Fe, and Mn in the pore water of the top 0 to 20 cm of sediment were 2.2 to 10.0 nM, 346.0 to 950.0 nM 243.8 to 454.8 nM, 23.2 to 51.2 nM, 39.8 to 249.5 μM, and 13.4 to 20.7 μM, respectively. Enrichment of these trace metals was observed in the upper 0- to 7-cm layer. Profiles of conditional distribution coefficient, log(KD), of the trace metals and results of multiple regression analysis have revealed that reduction of Mn (hydrous) oxides was the major remobilization mechanism for Cd, Cr, Cu, Pb, and Zn in the mudflats. Benthic diffusive fluxes of these trace metals from the mudflats were also estimated on the basis of the concentration gradients of trace metals between surface sediments and the overlying water column. The magnitude of the estimated diffusive fluxes followed the order Zn > Cr > Cu > Pb > Cd.

Ancillary