滇池沉积物磷内负荷及其对水体贡献的研究

Sediment burden and release potential of phosphorus to water in Dianchi Lake, China

在滇池全湖选取 1 1 0个采样点 ,调查了沉积物磷的营养状况 ;外海不同方位选取 6个采样点 ,研究了沉积物磷的赋存形态、剖面分布及其对水体的贡献 .结果表明 ,滇池沉积物表层 ( 0～ 5cm)总磷含量主要变化在 2～ 3g·kg-1 ,最大值为 6 6 6g·kg-1 .沉积物剖面表明 ,表层总磷含量远高于底层 ,在 0～ 1 0cm总磷含量随深度增加而迅速降低 .在点 4、点 5和点 6 ,不同形态磷的含量顺序为NaOH P ,Org P >HCl P >BD P >NH4Cl P .滇池南部 (S1、S2 )沉积物钙结合态磷含量较高 ,表现为HCl P >NaOH P ,Org P >BD P >NH4Cl P(表层 0～ 2 0cm) .沉积物表层 0～ 1 0cm活性磷含量很高 ,且随深度增加含量急剧下降 ,滇池北部沉积物具有很大的释磷潜力 .可溶性磷在水 土界面的浓度梯度为沉积物磷向水体扩散提供了条件 。

Surface sediments were sampled from 110 sites to investigate P content in sediment in Dianchi Lake and six core samples from Wai-Hai were used to study profiles distribution and chemical forms of phosphorus, and their contribution to lake water. Total P (TP) concentrations in surface sediments (0～5?cm) ranged from 2?g·kg^(-1) to 3?g·kg^(-1), and the maximum value was 6.66?g·kg^(-1). TP contents in sediment profiles showed that P in surface layers was much higher than that in bottem layers and decreased rapidly with depth from the top layers (0～10?cm). At site 4, 5 and 6, the concentrations of different P forms followed the order: NaOH-P, Org-P>HCl-P>BD-P>NH_4Cl-P in the whole profile. In southern lake (at S1 and S2), Ca|P content was higher and the ranks in the order of HCl-P>NaOH-P, Org-P>BD-P>NH_4Cl-P in top 20?cm sediment layers. In Dianchi Lake the amount of mobile P on top 10-cm sediment was very high and declined rapidly with depth. The sediments in northern lake had a large release potential. A gradient of the reactive soluble phosphorus (SRP) occurred at the sediment-water interface, which indicated that SRP could diffuse from sediment into the overlying water. The results suggested that a considerable potential P could be released from the sediment to the water and sediment P burden would be the dominant factor influencing water quality in Dianchi Lake.