高岚河不同降雨径流类型磷素输出特征

通过对三峡水库次级支流高岚河流域不同强降水过程中水量、水质变化过程的同步监测,系统分析了产流过程中不同形态磷素浓度及通量变化的规律,解析场次降雨事件点源和非点源磷素入库负荷.结果表明,"矮胖型"降雨径流变化过程表现出迟滞性,而"尖瘦型"降雨径流为快涨快退;强降雨冲刷产生的泥沙携带大量颗粒态磷进入水体,使得总磷含量迅速增加,溶解性总磷和正磷酸磷浓度略微升高;相对于"矮胖型"降雨,"尖瘦型"强降雨产生的总磷浓度及通量极大值均高于"矮胖型"降雨,泥沙侵蚀效果更为明显;不同雨型下,磷通量与浓度随时间的变化过程和流量的变化过程具有大体一致性;各磷素在强降雨过程中流失非点源污染占90%左右,由于"矮胖型"降雨径流历时较长,非点源总磷负荷贡献率大于"尖瘦型".

Phosphorus Output Characteristics Under Different Rainfall-Runoffs in Gaolan River

Through capturing the dynamics of water quantity and quality during varied intensities of rainfall, the variation characteristics of different forms of phosphorus and flux during the producing of runoff were studied systematically in Gaolan River watershed (a secondary tributary of Three Gorges Reservoir). Meanwhile, the phosphoric loadings from point and non-point sources were identified, respectively. The results show that: the variation of rainfall-runoff under "squat" rain was relatively slow, while under "pointed thin" rain it presented quickly both during rising and recession. Total phosphorus concentration increased quickly because soil carried particulate phosphorus into water under the heavy rainfall, while the relative variations of dissolved total phosphorus and orthophosphate concentration were slightly elevated. Compared with "squat" rain, the maximum value of total phosphorus concentration and flux were both higher in "pointed thin" rain, which led to the more heavily soil erosion. The dynamics of flux and concentration of phosphorus were generally consistent with that of the flow rate between the two different types of rain. Phosphorus from non-point source accounts for 90% during the whole heavy rain. Because of the long lasted time during "squat" rain, the contribution of the "squat" rain outweighs the "pointed thin" rain.