丹江口水库总磷时空分布特征及其影响因素

Spatial and temporal distribution characteristics and influencing factors of total phosphorus in Danjiangkou Reservoir

磷作为湖库富营养化的主要限制因子,一直是流域水环境研究关注的重点。基于长序列监测数据,系统分析了丹江口水库总磷的时空分布特征,并通过污染物通量核算深入分析了水库总磷演化的影响因素。结果表明:近10 a丹江口水库库区内总磷浓度基本稳定在Ⅰ~Ⅱ类,个别年份偶有升高,入库河流总磷浓度稳中有降。2021年水库总磷明显升高,升高时段集中在秋季,升高区域集中在汉库,水库总磷升高主要受入库河流输入的影响。罕见的2021年汉江秋汛是丹江口水库总磷升高的根本原因,持续的强降雨致使面源污染负荷大幅增加,全年总磷入库通量达到2018~2020年的3.2~7.6倍。研究结果可为丹江口水库总磷污染防控提供参考。

Phosphorus,as the main limiting factor of lake eutrophication,has always been the focus of watershed water environment research.Based on the long-sequence monitoring data,this study systematically analyzed the spatial and temporal distribution characteristics of total phosphorus in Danjiangkou Reservoir,and deeply analyzed the influencing factors of the total phosphorus change in the reservoir through pollutants flux accounting.Results showed that the total phosphorus concentration in Danjiangkou Reservoir was basically stable in class I~II in recent 10 years,and occasionally increased in some years.The total phosphorus concentrations in the inflow rivers were stable and slightly decreased.In 2021,the total phosphorus in the reservoir increased significantly,and the increase period concentrated in autumn,and the increase area was mainly in Hanku Reservoir.The increase of total phosphorus in the reservoir was mainly affected by the input of the rivers.The rare autumn flood of the Hanjiang River in 2021 was the root cause of the increase of total phosphorus in Danjiangkou Reservoir.Continuous heavy rainfall resulted in a significant increase in non-point source pollution load,and the annual total phosphorus inflow flux reached 3.2~7.6 times of that in 2018~2020.The results can provide reference for the prevention and control of total phosphorus pollution in Danjiangkou Reservoir.