摘要
考虑到已吸附在沉积物上的那部分可交换态P,从经典的Langmuir吸附等温线模型出发,推导出适合描述P在已有P污染的沉积物上吸附定量数学模型,并用此模型对P在6个太湖沉积物样品上吸附实验数据进行了拟合.拟合结果得到最大吸附容量(Γmax),Langmuir吸附平衡常数(k).利用所得的拟合参数通过公式计算方法得到原有易交换态P(NAP),临界磷平衡浓度(Czep),以及固 液分配系数Kp值.最后通过线性回归数据分析方法发现分配系数Kp,吸附容量Γmax都与沉积物中活性态Fe和Al含量呈良好的线性关系,表明太湖沉积物中活性Fe和Al是对P持留的主要作用者.
There is substantial evidence that sediments can act as a phosphorus “buffer' controlling the concentrations in the surface water through interactions with suspended particles. It is essential to study the adsorption-desorption behaviors of phosphorus on sediment-water interface for further understanding the mechanism of eutrophication and evaluating the probability of eutrophication restoration. Classic Langmuir isotherm equation has been widely used as a model to describe P adsorption characteristics on various sorbents. However, when it is applied to phosphorus adsorption on native phosphorus polluted (NAP-polluted) sediments the classic Langmuir equation cannot simulate precisely because it neglects that NAP simultaneously takes part in sorption equilibrium in phosphorus adsorption experiments. A modified model was deduced from classic Langmuir isotherm to describe phosphorus adsorption properties on NAP-polluted sediments. All sets of data of P sorption on six sediment samples collected from Taihu Lake were fitted to the modified model, and the values of the maximum sorption capacity (Γ_(max)),phosphorus binding constant (k), native adsorbed exchangeable phosphorus (NAP), zero equilibrium phosphorus concentration (C_(zep)) and partitioning coefficient (K_p) were subsequently obtained. Whereafter, the linear correlation between Γ_(max) and the content of active iron and aluminum was found out. It could be explained by the fact that iron and aluminum (hydr)oxides were the primary undertakers to adsorb and retain phosphorus in sediment due to their relative larger specific surface area. Meanwhile, the similar relationship between K_p and active iron and aluminum contents was also found in the sediments of Taihu Lake. Therefore, it was believed that active Fe and Al might play a predominant role in adsorption and retention of exchangeable phosphorus in the sediment of Taihu Lake.
出处
《环境科学学报》
CAS
CSCD
北大核心
2005年第1期64-69,共6页
Acta Scientiae Circumstantiae
基金
中国科学院知识创新工程重大项目(KZCX1 SW 12)
