降雨事件下洱海北部主要入湖河流污染物特征分析

The characteristics analysis of pollutants from main rivers entering the lake in the northern Erhai Lake under precipitation events

通过研究2019年雨季(7—9月)洱海最主要的入湖河流污染物特征,对流域内6场次降雨下的污染物浓度与负荷进行监测,阐述6种污染物特征,计算入湖负荷,并评估对洱海的水质影响。结果表明:弥苴河是北三江流域径流与污染物入湖的主要贡献来源,径流量占北三江流域入湖总径流量的47%,氨氮、硝态氮、可溶性总氮(TDN)、正磷酸盐、可溶性总磷(TDP)和化学需氧量(COD)入湖负荷分别占总负荷的40.5%、65.0%、55.0%、55.0%、54.1%、57.1%;TDN、TDP、氨氮、COD污染负荷之间都存在着不同程度的相关性,降雨是影响氮磷等典型污染物负荷入湖的主要因素。雨季径流携带大量养分入湖使水体养分浓度升高,导致水体环境质量下降。因此在雨季控制径流携带污染物入湖,对防控洱海水质持续下降具有重要意义。

The characteristics of pollutants entering Erhai Lake during the rainy season of 2019(July-September)were studied.The concentration and load of pollutants under six rainfall events in the basin were monitored,the characteristics of six pollutants were expounded,the load into the lake was calculated,and the impact on the water quality of Erhai Lake was assessed.The results showed that:Miju River was the main contributor of runoff and pollutants into the Three-River watershed,accounting for 47%of the total runoff into the lake.The pollutant load of Miju River accounted for 40.5%,65.0%,55.0%,55.0%,54.1%and 57.1%of the total load of ammonium nitrogen,nitrate nitrogen,total soluble nitrogen(TDN),polyphosphate,total soluble phosphorus(TDP)and chemical oxygen demand(COD),respectively.The pollution loads of TDN,TDP,ammonium nitrogen and COD demand were all correlated to different degrees.Rainfall was found to be the main factor affecting the typical pollutant loads of nitrogen and phosphorus into rivers and lakes.The runoff in the rainy season carries more nutrients into the lake,increasing the concentration of water nutrients and leading to the decline in water environmental quality.Therefore,the control of runoff carrying pollutants into the river during rainy season is of great significance for preventing the continuous decline of water quality in Erhai Lake.