| The paper studied on (1) Sedimentatary fluxes and rates of Daya Bay; (2) Vertical profiles of microelements and amino acids in sediment of Daya Bay; (3) Adsorption behaviors of artificial radionuclides on surface sediment of Daya Bay and (4) Uptake behaviors of the radionuclides by marine bivalves and phytoplankton algae.1 Four sediment cores of Daya Bay, the South China Sea, were dated by excess 2lç™™b geochronology, and the variations of sedimentatary fluxes and rates with time were investigated. Results showed that (1) The ages of the 60-cm-length cores at station WO, W2, W6 and W9 were 124, 109, 109 and lOlyears respectively. (2) The sedimentatary fluxes and rates increased continually with years during the past 100 years before 1998. (3) The average sedimentatary rates during past 10, 20 50 and 100 years before 1998 were 1.28, 1.15, 0.92 and 0.74 cm yr"1 respectively.2 Fe, Mn, Zn, Sr, Cu, Pb, Cd, As, Cr and Co in four cores were partitioned into four operationally defined geochemical fractions (acid extractable, reducible, oxidizable and residual) by BCR four-step sequential extraction procedure. Variations of sedimentatary fluxes of the elements with time were studied based on geochronology of the cores. Results demonstrated that (1) The remarkable variations of subordinate fractions of an element with depth, which may be more environmentally, ecologically and biogeochemically important than dominating fractions, could be submerged completely by insignificant variation of dominating fractions of the element. (2) Elements in sediment could change from one fraction to another during burying. (3) Sedimentary flux of heavy metals to Daya Bay contributed by external input sources varied remarkably since 1980's, the years of rapid industry developing of the area.3 Vertical profiles 12 free amino acids (FAA) and 12 hydrolysable amino acids (HAA) in the cores and the results showed that (1) Contents of FAA and HAA decreased with depth and the down-coretrends of total FAA and total HAA can be described by exponential equation of cz = 1.60 e~l22z and cz = 16.3 e-0.00472, with the correlation coefficient of-0.97 and -0.90, respectively. (2) The down-core trends of mole fractions of free (xr) and hydrolysable (XH) amino acids were: both XF and XH of aspartic acid and glycine increased with depth; both XF and XH of threonine, valine, isoleucine and leucine decreased with depth; XF decreased and XH increased with depth for glutamic acid; XF increased and XH decreased with depth for serine and alanine. (3) The ratios of xFio XH of amino acid heavily dependent on its' structure and amino acids with similar structure had approximately the same ratio. The ratios of XF to XH for straight aliphatic, hydroxyl, acidic, basic and branched aliphatic amino acids were 1.48, 1.02, 0.86, 0.67 and 0.50 respectively. There were no relevant reports in literature.4 Adsorption behaviors of ten environmentally and ecologically important radionuclides on surface sediments of Daya Bay were studied and the results showed that (1) There was a valley in the kinetics curve of 103Ru, 106Ru, 95Zr and 95Nb. (2) Kds of 103Ru, I06Ru, 95Zr, 95Nb, 60Co, 65Zn, 110mAg) 137Cs, l24Sb and 85Sr were 3.6xl03,5.9xl03, 1.5*104, 1.6xl05, 3.8xl03, 2.0xl03, 4.4xl03, 8.7xl02, 80 and 70 respectively after 113 days adsorption.5 The behaviors of bioaccumulation and tissue distribution of the above radionuclides in marine bivalves (Saccostrea cucullata, Perna viridis, Pinctada martensi ) were investigated during an exposure time of 14 days. The results showed that (1 )The majority of 95Zr, 95Nb, 106Ru and60Co were distributed in the shells and byssl of bivalves. (2) Soft tissues of bivalves had high concentration factors for 110mAg and 65Zn. (3) Concentration factors of l37Cs, 85Sr and l24Sb in shell and soft tissue bivalves were low. (4) Uptake behaviors of 103Ru and 106Ru by bivalves were great differences: most of 103Ru uptake by the bivalves was in shells and 106Ru mainly distributed in soft tissues.6 The concentration biokinetics...
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