Geochemical Modeling And Significance Of Speciation Of The Trace Element In Aquatic Environment In The Jiaozhou Bay

Water, surficial sediment, clam were sampled from the Jiaozhou Bay. The chemical analysis mainly focused on trace elements. Firstly, this thesis reveals the response of the clam to the exposures and absorbtion characteristic with the selectivity by studying trace elements distributions in the aquatic environment of the Jiaozhou Bay. Secondly, it puts forward the elements not only exist with simple ionic form but with complicated complexed forms by the geochemical modeling of Cu, Pb, Zn, Cd, Cr, Hg, As. Thirdly, the regression of the concentrations reveals the concentrations in the clam are not controlled by the sediment chemistry but by the bottom water and pore water chemistry, and figures out that bioaccumulation of Cu, Hg, As in clam correlated with their respective concentration in the bottom water, while bioaccumulation of Pb, Zn, Cd, Cr correlated with their respective concentration in the pore water. Furthermore, the dissolved speciations of trace metals have been simulated by PHREEQC. The results indicate that â‘ Cu(OH)₂, HgCl₃^-", HAsO₄^2- are dominant species and Cu²⁺, HgCl₄^2-, HAsO₄^2- are bioavailable species of the bottom water. â‘¡PbCO₃, Zn²⁺, CdCl₂, Cr(OH)₃ are dominant species of the pore water, while PbSO₄, ZnOHCl, CdCl⁺ Cr(OH)₂⁺ are bioavailable species. So the author concludes that the trace element bioaccumulations in aquatic environment are essentially controlled by the concentrations of bioavailable species, rather than the total concentrations of trace metals or the contents of their dominant species. Finally, it summarizes the responses of human and bio-organism to the exposures, and points out that the countermeasures of protecting the contaminated aquatic ecosystems.