西苕溪流域沉积物及土壤对磷吸附/解吸特性研究

Adsorption and desorption characteristic of phosphorus in reservoir sediments and soil of West Tiaoxi catchment

以赋石水库和其上游河道沉积物以及流域内代表性水稻土为对象,通过分析其理化性质,改变上覆水磷浓度和pH的方法探讨沉积物和土壤对磷吸附/解吸的影响。结果表明:(1)沉积物内较高的磷含量,导致吸附/解吸平衡浓度较高,因此在水库和水体中起着磷"源"的作用;(2)土壤最大磷吸附量为566.45mg/kg,远大于沉积物的吸附量,同时吸附/解吸平衡浓度较低,因此在治理湖泊富营养化时,要加大水土保持的力度,尽量减少作为最主要污染源的农田土壤磷素流入水体;(3)无论上覆水中磷浓度升高还是降低,在未达到吸附/解吸平衡浓度前,土壤和沉积物会持续释放磷,故应把水体治理的重点放在降低土壤和沉积物的磷含量上;(4)上覆水的pH对样品的磷吸附和释放都有显著的影响。在酸性(pH<3)或碱性(pH>9)环境下,样品的磷吸附量均急剧下降,而水体酸化更易导致平衡后上覆水磷浓度的降低。

The sediment in Fushi Reservoir and the typical paddy soil in reservoir basin were collected as research object to analyze their physicochemical properties.The adsorption and desorption behavior of phosphorus in sediments and soil was investigated under different initial phosphate concentration and pH.Research indicates that：（1）high-level of phosphorus sorption-desorption equilibrium concentration can be attributed to the high phosphorus concentration within the sediments,which made the sediments as resources of phosphorus in water bodies.（2）The maximum adsorption of soil was 566.45 mg/kg,which was larger than that of sediments.Therefore,increase of the investment in soil and water conservation and decrease of the phosphorus loss from field into water bodies should be strengthened in the eutrophication control.（3）The soil and sediments will release phosphorus into the overlying water until the phosphorus concentration reached the sorption-desorption equilibrium concentration.（4）There was remarkable influence of pH of the overlying water on both adsorption and desorption of phosphorus.The adsorption of phosphorus decreased rapidly when p H〈3 or p H〉9,however,the acidification of the water bodies can decrease the phosphorus concentration of the overlying water.