不同粒径泥沙理化特性对磷吸附过程的影响

以北京大兴南海子湖表层沉积物为研究对象,测试分析了0.147～0.246 mm(细砂)、0.074～0.147 mm(极细砂)、0.0385～0.0740 mm(粉粒)和<0.0385 mm(粉粒粘粒混合物)4种粒径泥沙对磷的吸附行为,并采用相关分析及逐步回归分析探讨不同粒径沉积物中有机质(OM)、Fe、Al、Ca、Mn和TP含量对磷吸附过程的影响。结果表明,二级动力学方程和Langmuir模型能较好地描述南海子不同粒径泥沙的吸附动力学及等温吸附过程(R2>0.90)。粒径对单位质量泥沙吸附磷量具有明显影响,粉粒粘粒混合物>粉粒>细砂>极细砂。总体上,泥沙有机质(OM)、TP、Fe、Al、Ca和Mn含量随粒径的减小而增大,且粘粒对其影响较大。不同粒径泥沙(OM)、Fe、Al、Ca和Mn含量之间存在极显著正相关关系(P<0.01),且均对单位质量泥沙最大吸附量(Xm)和饱和吸附量(Cse)具有正效应,其中Al含量对该参数的影响更为显著。这说明泥沙对磷的吸附行为可能受到粒径和化学成分的共同影响。

Effect of sediment physicochemical properties on phosphorus sorption for different size particles

The surface sediments samples were collected from Nanhaizi Lake in Beijing. The phosphorus sorption behaviors on four particle size sediments including 0.147~0.246 mm(fine sand), 0.074~0.147 mm (very fine sand),0.0385~0.0740 mm(silt),<0.0385 mm (mixture of silt and clay) were determined. The effects of sediment organic matter (OM), TP, Fe, Ca,Al and Mn on phosphorus sorption were analyzed using correlation analysis and stepwise regression. The results showed that the second order kinetics model and Langmuir isotherm equation could well describe the behaviors of the phosphorus sorption with determining coefficients R² of>0. 90). The maximum sorption mass (X_m) of different size particles was in the order of silt and clay>silt>fine sand>very fine sand. The content of OM, TP, Fe, Ca, Al and Mn increased with the decreasing particle size and the fraction of clay particles had more important effect on them than other particles. There was a significantly positive correlation (P<0.01) among the content of Fe,Ca,Al,Mn,OM. All these chemical compositions, especially Al, had a clearly positive effect on the X_m and equilibrium concentration (C_se) on the sediments. These results indicate that the phosphorus sorption could be jointly affected by both sediment particle size and chemical composition.