滇池水体不同形态磷负荷时空分布特征

Spatial and temporal distribution patterns of loadings of different phosphorous forms in Lake Dianchi

利用Arc GIS空间插值的方法,通过2013年逐月监测(12个月)36个站点水量及不同形态磷浓度,揭示滇池水体磷浓度和磷负荷的时空变化,并探讨不同形态磷负荷的组成贡献,旨在为进一步实施滇池水污染治理及污染负荷控制提供依据.结果表明:滇池水体总磷(TP)浓度在0.13~0.46 mg/L之间,其中颗粒态磷(PP)浓度占TP浓度的72.6%,溶解性活性磷(SRP)浓度占TP浓度的12.8%,溶解性有机磷(DOP)浓度占TP浓度的14%;2013年水体TP负荷为251 t/a,其中PP负荷为190 t/a,SRP负荷为26 t/a,DOP负荷为34 t/a;滇池水体PP负荷对TP负荷的贡献最大,为76%,其次为DOP和SRP,贡献分别为13%和10%;TP及不同形态磷浓度与其负荷在季节分布上差异显著,负荷随季节变化呈现秋、冬季较高,春、夏季较低,而浓度呈现夏、秋季较高,冬、春季相对较低的趋势.定量评估滇池水体不同形态磷负荷及其组成贡献,对进一步揭示滇池藻源和泥源内负荷对水污染的贡献具有重要意义.

With the help of GIS spatial interpolation, based on the monthly observed data of water yield and phosphorous （P） concentrations in 36 sampling sites in Lake Dianchi, the loading contributions of different P forms was explored and the spatial and temporal patterns of the P concentrations and loadings were revealed in this paper, aiming at providing evidence for water pollution treatment and inner loading control. The results showed： The changes in total phosphorus （TP） concentrations in the water ranged between 0.13 and 0.64 mg/L, among which particulate phosphorus （PP） covered 72.6%, soluble reactive phosphorus （SRP） 12.8%, and dissolved organic phosphorus （DOP） 14%. During 2013 the average annual TP loading was 251 t/a, among PP loading 190 t/a, SRP 26 t/a, and DOP 34 t/a. TP loading in Lake Dianehi was mostly contributed by PP loading, averaging 76%, and secondly by DOP and SRP, averaging 10% and 13%, respectively. There was a significant difference in seasonal distributions in TP concentrations and loadings and in different P forms. The concentration was characterized with a higher value in summer and autumn in contrast to a relatively low value in winter and spring, while the loading was characterized with a higher value in autumn and winter in contrast to that in spring and summer. Thus, to quantitatively assess the loading of PP and SRP as well as their contributions to TP, was of great importance in guiding the control over the inner loading in Lake Dianchi.