滴水湖沉积物对磷的吸附特性初探

在滴水湖湖底典型区域采集表层沉积物,研究其对上覆水中磷的吸附特征。结果表明,滴水湖5个采样点沉积物对上覆水中磷的"快吸附"过程发生在0～4 h内,吸附速率达3.08～5.65 mg/(kg.min)",慢吸附"发生在4～24 h内,速率为0.54～1.34 mg/(kg.min),24 h后达到动态平衡状态。抛物线扩散方程Ct=C0-kt1/2可很好地拟合沉积物对磷的吸附动力学过程。当上覆水磷浓度低于0.18～0.20 mg/L时,各采样点处沉积物对磷的吸附量很低或呈负吸附状态,之后磷吸附量随初始磷浓度的增加而增大;湖心处本底吸附态磷(NAP)较高,为6.871 mg/kg;一号码头和南岛处沉积物的磷吸附解吸平衡浓度(EPC)0较低,分别为0.18和0.22 mg/L,纳磷潜力较大;Langmuir等温吸附模型比Freundlish模型更适用于描述沉积物对上覆水高浓度磷的等温吸附过程。滴水湖沉积物对磷的吸附容量范围为322.58～1 250.00 mg/kg,其中南岛处沉积物吸附磷容量较大,对上覆水中高磷浓度的变化缓冲力较强,但同时也是重要的磷库,应密切关注该处磷含量的变化。

Preliminary Study of Characteristics of Phosphorus Adsorption on Sediment of Dishui Lake

The preliminary study began with sampling and samples treatment of top-layer sediment of five different points over Dishui Lake,and was followed by experiments of adsorption kinetics and isothermal adsorption.Results indicated that adsorption of phosphorus contained in the overlying water on the sediment mostly occurred within the initial 24h and hence came to the equilibrium state;the equation of parabolic diffusion,i.e.,Ct=C0-kt1/2,could well fit the kinetic process of phosphorus adsorption;and the higher initial P concentration in the overlying water would lead to more amount of P adsorption.As to the models to describe the adsorption process,this paper noted that the Langmuir equation was more appropriate than the Freundlich equation.In addition,it was found that sediment sample collected near South Isle showed the biggest capacity of P adsorption,which meant that the sediment around here,could have stronger buffering effect against possibly increased P concentration in the water and could,at the same time,become a phosphorus storage,which should be more concerned with.