Phosphorus Release and Absorption of Surficial Sediments in Taihu Lake under Simulative Disturbing Conditions

Abstract

利用恒温震荡器构筑的模拟扰动环境,研究了太湖水-沉积物界面的磷释放和吸附行为.结果表明:表层沉积物的磷酸盐释放作用在模拟扰动条件下并不十分明显,在低强度的扰动条件下未观察到释放现象,模拟高强度扰动后,出现一个相对较强的释放过程.最大释放时沉积物上覆水浓度约为低强度扰动时的3倍.最大释放时间(T_max)可能受磷酸盐形态分布的不同而有所差异.相比较而言,磷酸盐的吸附作用表现得十分明显且迅速,沉积物上覆水磷酸盐浓度在0.5h后分别由0.229mg/L和0.215mg/L下降为0.05mg/L和0.013mg/L.可以看出当上覆水磷酸盐浓度较高时,吸附作用的强度远大于释放作用.在25℃,模拟中等强度(100rpm)的模拟扰动条件下,当初始磷酸盐浓度为1.01mg/L时,梅梁湾和五里湖的表层沉积物吸附容量分别为每克干重吸附0.042mg和0.050mg磷酸盐.这种较高的吸附能力对浅水湖泊的磷酸盐缓冲作用能起到积极作用.;The phosphorus release and abso rption of surficial sediment s in Taihu Lake w as studied under simulative disturbing conditions.The results show ed that the sediment release effect s of the Wulihu Lake and the Meiliang Bay w ere not as remarkable as expected.Under lower disturbing intensities, the release processes were not obvious.As the disturbing intensity became greater, an obvious release process w as observed.The t ime needed in getting maximal release was distinct because of the different phosphorus constitutions. The phosophorus abso rptio n w as obivous under simulative condition.The phosphorus concentrations of upper water of surficial sediments in Taihu Lake w ere reduced from 0.229mg/L and 0.215mg/L to 0.05mg/L and 0.013mg/L under disturbing condition of 100rpm and 25℃, respectively.The experiment show ed that the abso rption intensity w as much g reater than the release intensity in higher phosphorus concent ration of upper water of surficial sediment.Under 25℃ and moderate disturbing intensity (100rpm), w hen the initial phosphorous concentration w as 1.01mg/L, the absorption capacity of surficial sediments of the Meiliang Bay and the Wulihu Lake could be up to 0.042mg and 0.050mg phosphorus per gram dry sediment.This huge absorption capability of surifical sediment may play a positive role in phosphorus buffering in shallow lakes.