Biogeochemical Characteristics and Its Environmental Significance of Heavy Metals in the Sargassum Cells in Daya Bay, China

In order to make a comprehensive analysis of the heavy metals pollution and potential ecological risk in Daya bay, China, this paper focuses on seawater-sediment-Sargassum system as research object and analyzes the geochemical and biogeochemical characteristics for Cu, Pb and As in the seawater, surface sediment, Sargassum and cells of Sargassum. The results show that the concentrations of Cu, Pb and As are lower than the values of grade Ⅰ national standards for sediment, but some are of high-value in some sampling sites because of the source of input. The biological absorption coefficients indicate that the accumulation ability of heavy metals for Sargassum is arranged from high to low, as follows: As > Pb > Cu and Sargassum exhibits high abilities of accumulation of As. The study of the ultrastructure using transmission electron microscope reveals that the cell structures of Sargassum are anomalous and aberrant and there are lots of relatively high electron-density substances diffuse in the cells. The energy-dispersive spectroscopy (EDS) analysis shows that Cu, Pb and As in the form of comparatively high electron-density substance diffuse in the cell structures induce irreversible damage to the cell. The results provide the forepart warning information for ecological environment of Daya bay.