太湖春季沉积物间隙水中磷的分布特征及界面释放的影响

通过对太湖春季不同湖区水体和沉积物间隙水中磷的分布特征研究,探讨了间隙水中磷的释放对上覆水环境的影响。结果表明,颗粒态磷(PP)和溶解态有机磷(DOP)是太湖水体中主要的磷形态,占总磷的58%～95%。不同湖区沉积物间隙水磷的剖面变化可能与生态特征及水动力引起的沉积物-水界面的扰动强度密切相关。湖心和西部沿岸沉积物扰动强烈,致使间隙水中磷含量向上逐渐降底,而梅梁湾和贡湖间隙水磷的垂向变化不大。东太湖和竺山湖沉积物界面间隙水中磷含量偏高,可能是由于表层沉积物的有氧环境使Fe2+被氧化固定下来,并促进了总磷(TP)和溶解态活性磷(DRP)的扩散释放。总体而言,间隙水中各形态磷具有向上覆水体释放的趋势,其中DRP的扩散潜力最大,竺山湖沉积物-水界面DRP扩散通量高达11.42mg.m-2.d-1,表明春季浮游植物的复苏生长对DRP的迫切需求。

Distribution patterns of phosphorus forms in sediments interstitial water of Lake Taihu and the effects of sediment-water phosphorus release in spring

This paper studied the spatial distribution patterns of phosphorus(P) in the water body and sediment interstitial water in different areas of Taihu Lake,and the effects of the P release from the interstitial water on the overlying water environment.In the water body of the Lake,particulate P and dissolved organic P were the two dominant P forms,accounting for 58-95% of the total P.The profile distribution of sediments interstitial water P differed in different areas of the Lake,which could have close relations to the ecological features and the turbulence intensity of the sediment-water interface induced by hydrodynamics.The P concentration in the sediment interstitial water in the Lake center and its western coast decreased gradually upward due to the drastic sediment disturbance,whereas that in the Meiliang Bay and Gonghu had little vertical change.Higher P concentration was observed in the interface water in east Taihu Lake and Zhushan Lake,possibly due to the aerobic condition in surface sediment layer making the Fe(Ⅱ) oxidized and fixed,and due to the promoted diffusion and release of TP and dissolved reactive P(DRP).On the whole,almost all the P forms in interstitial water had a trend of releasing to the overlying water,and DRP had the greatest potential,with the diffusion flux of DRP up to 11.42 mg·m-2·d-1 in the Zhushan Lake,which implied the urge need of DRP by the phytoplanktons for their recuperative growth in spring.