上海滴水湖周边土壤和沉积物对磷的吸附特征

Phosphorus Adsorption Characteristics of Soils and Sediments Surrounding Dishui Lake in Shanghai

采集滴水湖沉积物及其引水河与排水河沉积物、湿地沉积物以及周边农田土壤进行磷的等温吸附实验,探讨不同来源物质对磷吸附特性的差异.结果表明,滴水湖沉积物的吸附/解吸平衡质量浓度(EPC0值)为0.11~0.63 mg·L-1,高于其他来源土壤和沉积物,更容易向上覆水体释放磷.Langmuir模型和Freundlich模型对磷的等温吸附都有较高的拟合程度.由Langmuir模型计算的最大吸附量(Qm)表明,不同来源土壤和沉积物对磷的吸附能力由高到低为河流沉积物(1 003.05~2 977.65 mg·kg-1)>滴水湖沉积物(669.77~1 717.94 mg·kg-1)>湿地沉积物(368.60~1 145.51 mg·kg-1)>农田土壤(441.36~702.30 mg·kg-1).这表明农田土壤对磷的吸附能力最弱,当过量使用化肥时,农田会成为滴水湖磷的源.

Soils and sediments of different origins were collected,which included the cropland soils surrounding Dishui Lake,the sediments from rivers,the sediments of wetland and the sediments in Dishui Lake. These samples were used for the experiment of phosphorus isothermal adsorption. The results of this experiment were analyzed and fitted. It shows that,the adsorption-desorption equilibrium mass concentration( EPC0value) of the sediments in Dishui Lake( 0. 11-0. 63 mg·L- 1) is higher than that of the soils and sediments from other sources,which indicates that it is easier to release phosphorus to overlying water. Both the Langmuir model and Freundlich model have a high fitting degree to the isothermal adsorption of phosphorus. The maximum adsorption capacity( Qm) calculated by Langmuir model demonstrate that the adsorption capacity of soils and sediments from different sources follows the order: sediments from rivers( 1 003. 05-2 977. 65 mg·kg- 1) > sediments in Dishui Lake( 669. 77-1 717. 94 mg·kg- 1) > sediments of wetland( 368. 60-1 145. 51 mg·kg- 1) > cropland soils( 441. 36-702. 30 mg·kg- 1). It shows that the adsorption capacity of cropland soils is the weakest. Cropland soils can be a source of phosphorus in Dishui Lake when extra fertilizer is used.