西辽河沉积物有机组分对磷的吸附影响

采用平衡吸附法研究了西辽河沉积物不同有机组分对磷的吸附影响.结果表明,西辽河沉积物对磷的饱和吸附量Гm值为953.64mg/kg.吸附分配系数K值为40.50;去除有机质后的沉积物对磷的吸附能力大大降低,碳标化饱和吸附量Гmoc值和吸附分配系数Koc值分别只能达到原样的12.07%和27.49%,说明有机质是影响磷在沉积物上吸附的主要因素;沉积物有机组分中的轻组有机质是一类橡胶态胶体,磷在橡胶态胶体上的吸附以分配作用为主,其碳标化吸附分配系数为77.13;沉积物有机组分中的重组有机质对磷的吸附起主导作用,其碳标化饱和吸附量为1225.63mg/kg;重组有机质是一类玻璃态胶体,磷在玻璃态胶体上的吸附除分配作用外,还存在孔隙填充方式的吸附;重组有机组分中的紧结态腐殖质(胡敏素)对磷的吸附起关键作用,其碳标化饱和吸附量为3546.69mg/kg.影响机制主要为稳、紧结态腐殖质是形成沉积物疏松多孔团聚体结构的重要胶结物质.

Effect of organic matter on sorption of phosphorus on sediment in Western Liaohe River

Batch experiments of equilibrium adsorption were carried out to investigate the effect of organic matter on sorption of phosphorus on sediment in Western Liaohe River.The results indicated that the sorption capacity of the sediment was 953.64 mg/kg,and the value reduced dramatically after organic matter was removed.The partition coefficient of phosphorus on the sediment was 40.50.Normalized partition coefficient and normalized carbon sorption capacity only accounted for 12.07% and 27.49%,the value of partition coefficient and sorption capacity respectively,which indicated that organic matter was main factor influencing the sorption of phosphorus on sediment.Light fraction of organic matter was a rubber-like domain,and partition may be the main process of sorption of phosphorus on it.The normalized partition coefficient of phosphorus on the light fraction was 77.13.On the other hand,the heavy fraction of the organic matter was glass transition matrix,it played a leading role in the sorption of phosphorus and the normalized carbon sorption capacity was 1225.63mg/kg.The sorption mechanism of phosphorus on the heavy fraction may be microhole filling apart from partition.Furthermore,the normalized carbon sorption capacity of tightly combined humus(humin) of the heavy fraction was 3546.69 mg/kg.Stably combined humus and tightly combined humus were important adhesive material in the formation of loose organo-mineral complexes.These may be the main sorption mechanism of phosphorus on sediment.