滇池表层沉积物对磷的吸附特征

在室内模拟条件下,从滇池表层沉积物对磷的吸附动力学与热力学两个角度出发,研究了滇池沉积物对磷的吸附特征,同时探讨了不同磷形态对磷吸附特性的影响,结果表明:1滇池不同形态磷含量顺序为:有机磷钙(O-P)钙结合态磷(Ca-P)金属氧化物结合态磷(Al-P)残渣态磷(Res-P)可还原态磷(Fe-P)弱吸附态磷(NH4Cl-P);2沉积物对磷的吸附动力学过程分为2个阶段,即快吸附和慢吸附阶段.快吸附阶段主要发生在0~0.5 h内,而慢吸附阶段主要发生在0.5~4 h.滇池沉积物对磷的吸附过程主要在4 h内完成.3外海北部上覆水磷酸盐(SRP)浓度低于沉积物中磷的吸附/解吸平衡浓度(EPC0),可初步判断该区域沉积物有向上覆水体释放磷的风险.4不同区域沉积物磷的最大吸附量(Qmax)和总最大吸附量(TQmax)均以外海南部最大.5沉积物本底吸附态磷含量(NAP)与钙结合态磷(Ca-P)呈显著正相关关系(R2=0.5139,p0.05),而其他吸附特征参数与磷形态之间相关性均不显著.6与洱海、太湖等湖泊相比,滇池沉积物磷的本底吸附态磷(NAP)和最大吸附量(Qmax)均处于较高水平,磷污染较为严重.

Characteristics of phosphorus adsorption on surface sediments of Dianchi Lake

The exchange process of phosphorus (P) at the sediment-water interface from a plateau lake is regulated by equilibrium dynamics. Adsorption characteristics of phosphate on the surface sediments from Dianchi Lake were determined by kinetics and thermodynamics experiments. The relationships between adsorption parameters and P forms of sediment were also investigated. The results indicated that:1The rank order of P contents in the surface sediments was O-P>Ca-P>Al-P>Res-P>Fe-P>NH₄Cl-P.2Adsorption kinetics of phosphate on the surface sediments was divided into two stage, the rapid adsorption stage that mainly occurred in the first 0.5 h and the slow adsorption stage in 0.5~4 h. Afterwards, the process for all the sediments reached adsorption equilibrium.3The soluble active phosphorus (SRP) concentrations of overlying water in the northern coast of Waihai Lake and the Caohai Lake were significantly lower than Zero Equilibrium P Concentration(EPC₀)of the sediments. In contrast, the SRP concentrations of overlying water were significantly higher than the EPC₀ in the sediment from the other lake areas. These results indicated that P release is almost negligible for most areas of Dianchi Lake and large P release from sediments was mainly present at local lakes.4The maximum P-sorption capacity(Q_max)and the total maximum P-sorption capacity(TQ_max)of sediment were found at the southern coast of Waihai Lake.5Significantly positive correlation was found between native adsorbed phosphate(NAP)and Ca-P(R²=0.5139,p<0.05), but not for the others. 6Comparing with Taihu Lake, Poyang Lake and Chaohu Lake, the sediments from Dianchi Lake had the highest values of NAP and Q_max. These results indicated the P retention in the sediments of Dianchi Lake.