北运河表层沉积物对重金属Cu、Pb、Zn的吸附

首先分析了北运河6个采样点表层沉积物中重金属含量及相关基本特征。通过实验室模拟实验,利用分配系数Kd评价沉积物对重金属Cu、Pb、Zn的吸附特性,进一步考察了水体pH变化和有机质对重金属在北运河沉积物上吸附的影响。结果表明,沉积物中重金属的含量顺序为Zn>Cu>Pb,去除有机质后,沉积物对重金属的吸附能力显著降低,但各采样点中的重金属含量,沉积物对重金属吸附能力,以及沉积物中的有机质含量并没有明显相关性,这可能是因为不同采样点中有机质种类与结构不同导致的。总之,北运河沉积物对Pb有很强的吸附能力,其次是Cu和Zn,而且,Cu、Zn、Pb的吸附量随着pH的升高逐渐增大,水体pH值对于Zn的吸附影响更大。

Adsorption of heavy metals Cu,Pb,Zn over top sediment in North River Canal

The concentration of heavy metals (Cu,Pb,Zn) and the characteristics of top sediment from six sampling sites distributed in North River Canal were analyzed.The distribution coefficient K_d was used to evaluate the adsorption capacity of Cu,Pb and Zn over the top sediment.The effect of solution pH and dissolved organic matter on the removal efficiency was also studied.The results indicated that the adsorption capacity of sediments significantly decreased when the dissolved organic matter was removed from the sediments.However,there was almost no significant correlation among the amount of heavy metals in sediments,the adsorption capacity of sediments and the concentration of dissolved organic matter.This may be attributed to the different species and structures of DOC in the six sampling sites.All the sediments showed the highest selectivity towards Pb with a selectivity order of Pb>Cu>Zn and the adsorption capacity increased with the increase of solution pH.The solution pH had the maximum effect on the adsorption of Zn among the three hevay metals (Cu,Pb,Zn).