2021—2023年洞庭湖区总磷浓度时空变化分析

Temporal and Spatial Variation of Total Phosphorus Concentration in Dongting Lake from 2021—2023

基于2021—2023年洞庭湖“三市一区”总磷监测数据,对洞庭湖区总磷浓度的时空变化进行分析,结果表明,2021—2023年湖区水质监测断面总磷含量呈逐年下降、稳中向好的趋势。其中,西洞庭湖总磷达标情况较好,年均总磷浓度为0.046~0.049 mg/L;东洞庭湖区域总磷含量较高,年均总磷浓度为0.058~0.069 mg/L。2021—2023年,长江四口、环湖河流(汨罗江和新墙河)入湖口年均总磷含量明显高于长江四水,入湖口的总磷含量总体呈下降趋势,但资江2023年入湖口总磷含量比上两年有不同程度的上升。为实现洞庭湖总磷污染的精准管控,建议补齐入湖河流断面及跨界重点断面的流量监测点位建设,加强洞庭湖区农业面源污染治理以及入湖排口水质的动态监测。

Based on the monitoring data of total phosphorus in“three cities and one district”of Dongting Lake from 2021—2023,the temporal and spatial changes of total phosphorus concentration in Dongting Lake were analyzed.The results showed that:From 2021—2023,the total phosphorus content of the water quality monitoring section in the lake area showed a steady and positive trend,among which the total phosphorus content in the west Dongting Lake reached the standard better,with an average annual total phosphorus concentration of 0.046~0.049 mg/L,and the total phosphorus content in the East Dongting Lake region was higher,with an average annual total phosphorus concentration of 0.058~0.069 mg/L.From 2021—2023,the average annual total phosphorus content of the four estuary of the Yangtze River and the lake surrounding rivers(Miluo River and Xinqiang River)into the lake estuary was significantly higher than that of the four rivers of the Yangtze River,and the total phosphorus content of the lake estuary showed a downward trend in general,but the total phosphorus content of the Zijiang Lake estuary in 2023 increased to different degrees than that of the previous two years.In order to achieve accurate control of total phosphorus pollution in Dongting Lake,it is suggested to make up for the construction of flow monitoring points in the river section entering the lake and the key trans-boundary sections,strengthen the control of agricultural non-point source pollution in Dongting Lake area and the dynamic monitoring of water quality in the lake outlet.