湘江长沙段捞刀河口国控断面低氧成因研究

2021年6月10日起湘江长沙段捞刀河口国控断面出现溶解氧浓度未达到地表水Ⅲ类水质标准现象。为查清捞刀河口断面溶解氧偏低的成因,在该附近水域布设9个采样断面,于2021年7月16—22日开展调查监测。监测结果表明:国控断面捞刀河口水质自动站取水口溶解氧指标浓度降低主要受气温、气压、地形位置、受纳水体负荷、水体自净能力等因素影响。建议增加上游生态流量补充,并加强楚家湖、金竹河、苏托垸片区管理,采取截污、清淤等措施,减轻捞刀河污染物自净负荷,增强水体自净能力。

Since June 10,2021,the dissolved oxygen concentration in state-controlled section of Laodao estuary in Changsha section of Xiangjiang River failed to meet the class III water quality standard for surface water.In order to find out the cause of low dissolved oxygen in Laodao estuary section,9 sampling sections were set up in the nearby waters for investigation and monitoring from July 16 to 22,2021.The monitoring results showed that the decrease of dissolved oxygen index concentration at the water intake of the water quality automatic monitoring station in state-controlled section of Laodao estuary was mainly affected by such factors as air temperature,air pressure,terrain location,receiving water load,self-purification capacity of water body,etc.It is suggested to increase the upstream ecological flow supplement and strengthen the management of Chujia Lake,Jinzhu River and Sutuoyuan area,take measures such as sewage interception and dredging to reduce the self-purification load of pollutants in Laodao River and enhance the self-purification capacity of the water body.