Effects Of Organic Metter Composition And On Phosphorus Form And Adsorption/release Of Sediment From Yangzonghai Lake

In this study, spectral characteristics of hydrophilic and hydrophilic component and the <5k Da(LMW), 5-10 k Da(MMW)and >10k Da(HMW)molecular component of DOM in sediments of Yangzonghai Lake was clarified by the technical of XAD-8 resin separation and tangential flow ultrafiltration, and elementary composition for C, H, O and P froms in surface sediments and core sediments was investigated by the method of elemental analysis and phosphorus classification. The results indicated:(a) Contents of C, H and O in surface sediment of Yangzonghai Lake trended to decrease in contrast to the ratios of H/C and O/C increased from north to south; Contents of C, H and O in 0-18 cm core sediment decreased significantly in contrast to the ratios of H/C and O/C increased with incrasing depth.(b) The spectral values of SUVA254、E2/E3 and A240-400 of hydrophilic DOM increased in contrast to that of hydrophobic DOM decrease rom north to south. The SUVA254 and E2/E3 values of hydrophilic DOM were significantly positive correlation with content of C and H, but significantly negative correlation with the ratio of H/C and O/C in sediment.The E2/E3 value of hydrophobic DOM was significantly positive correlation with the ratio of H/C, but SUVA254 value of hydrophobic DOM was significantly negative correlation with the ratio of O/H.(c) The values of SUVA254, SUVA280, E2/E3, E2/E4, FI and BIX showed LMW>MMW>HMW, but the values of A2/A1, A3/A1, S275-295, T1, C, and the contehts of DOC, DON and DOP showed LMW<MMW<HMW. While the DOC<400 mg/kg, the ratio of DOC/DON increased in contrast to the ratios of DOC/DOP and DON/DOP decreasedwith increasing DOC contents. Contribution of HMW to DOC, DON and DOP decreased in contrast to MMW and HMW from north to south.(d) Contents of Mobile-P in the surface sediments ranged from 71.66 to 124.70 mg/kg,with an average value of 9.81% of TP; Contents of Immobile-P in the surface sediments ranged from 496.73 to 908.28 mg/kg, with an average value of 60.86 % of TP; The contribution of P form to accumulation of TP was calculated by the method of multiple linear regression analysis. The contribution of BD-P, Na OH-nr P and HCl to accumulation of TP is 70.55%, while the contribution of NH4Cl-P, Na OH-nr P and Res-P accumulation of TP is 29.45%.(e) The result of principal component analysis for C, H, O, H/C, O/C and O/H indexes in 80 samples showed that PCA was significantly positive correlation with C, O and O/H,but significant negative correlation with H/C and O/C. While OC≥3.97%, PCA factors was significantly positive correlation with BD-P, Na OH-nr P and HCl-P, but significant negative correlation with NH4Cl-P, Na OH-r P and Res-P.(f) The maximum adsorption amount of P on sediment(Qmax) was significantly positive correlation with H content in sediment and SUVA254, A240-400 of hydrophobic DOM, but significantly negative correlation with the O/H value of hydrophobic DOM; the adsorption intensity of P on sediment(K) was significantly negative correlation with C and H contents, but significantly positive correlation with H/C and O/C in sediment, the SUVA254, E2/E3 and A240-400 values of hydrophilic DOM.Thefore, content and structure of organic matter in sediment were the most important factors affecting P adsorption on and release from sediment. Humification, molecular weight, polarity and the intensity of electron transfer of DOM all played the key role in the behavior of P adsorption and release.