滇池沉积物内源磷释放初步研究

沉积物内源磷释放是湖泊富营养化重要的污染来源。本次研究在滇池20个采样点进行了原状柱状沉积物样品的采集。分析测试了分层沉积物样品的总磷、总氮、总有机质含量，揭示了滇池全湖沉积物中营养组分的含量特征和分布规律。为估算沉积物磷释放的通量水平和初步解释滇池磷释放的主要作用机制，现场提取出了沉积物间隙水，并分析了间隙水以及采样点湖水中溶解总磷、溶解磷酸盐和溶解有机磷的含量，根据实测运用费克扩散定律计算了沉积物-水界面之间磷的交换通量。同时对代表性样点进行了原样沉积物柱磷释放的实验室模拟。通量计算和模拟实验的结果表明，滇池沉积物具有较强的向水体的释磷能力，全湖沉积物平均磷释放通量为0．095mg／cm^2／a，沉积物磷释放成为全湖磷负荷的重要部分。实验数据相关性分析表明，滇池表层沉积磷活化释放的主要机制是表层沉积物有机质矿化降解，有机磷分解形成的浓度梯度驱动了溶解磷从沉积物向水体扩散。

Preliminary study on phosphorus release of internal load in Dianchi Lake sediment

In an investigation on redistribution of semimetal phosphorus and the internal load of phosphorus in Dianchi Lake, more than 20 undisturbed sediment-water cores have been sampled. The concentrations of total phosphorus, total nitrogen, organic carbon in sediment samples, and dissolved phosphorus have been analyzed. The dissolved total phosphorus both in water samples and pore water samples have been compared. The internal load of phosphorus has been calculated in terms of release fluxes of phosphorus from sediment by using Fick's law. The exchange of phosphorus between sediment-water-interface in some undisturbed sediment-water cores has been tested in laboratory and compared with the theoretical calculation. The study shows that the release flux of phosphorus from sediment ranged from 0.018 to 0.418mg/cm~2/a with average value of 0.095mg/cm~2/a. The study also indicates that the regeneration and release of sediment phosphorus in this lake could arise due to organic materials degradation. The conversion of organic forms of phosphorus in sediment is consideredas the main reason of phosphorus release.