基于环境容量的入湖污染负荷削减分析

水环境污染是困扰城市发展和影响人居生活的重要因子。为探索研究河湖水环境改善措施,尤其是研究与人居环境密切相关的城市内湖水环境提升,以武汉市南湖为例,开展了典型城市公园型湖泊的水质提升问题。通过对南湖汇水范围内污染物来源的进行精细化定量解析,结果结果表明南湖入湖总氮(TN)和总磷(TP)负荷分别为835.6 t/a和92.56 t/a;污染负荷空间分布有三个典型峰值区域,其面积仅占汇水范围的10.7%,而其TN产污负荷占25.18%,总磷产污负荷占23.97%。采用狄龙模型计算得出南湖水域TN环境容量为315.2 t/a,TP环境容量为21.01 t/a。在完成城镇生活污水和底泥释放中60%TN去除和75%TP去除的基础上,同时地表径流中TN控制率达到67%、TP控制率达到87%,即TN和TP排放量控制在环境容量限值以内,可使TN浓度达到1.5 mg/L,TP浓度达到0.1 mg/L,南湖水质总体达到地表水Ⅳ类要求。基于环境容量分析的入湖污染物来源定量解析,以及进一步对汇水范围内污染负荷的空间分析,可为河湖水环境污染治理措施的合理安排提供科学依据。

Measures analysis on water pollution control based on environmental capacity

Water pollution is an important factor that plagues urban development and affects human settlements. This study takes Lake Nanhu in Wuhan, China as an example to discuss the water quality improvement of typical urban lakes. Based on the quantitative analysis of the pollutant sources in the basin, the pollution load of TN and TP are 835.6t/a and 92.56t/a respectively. There are three peak regions in the spatial distribution of their pollution loads. In these three peak regions, 25.18% of TN and 23.97% of TP occupy the total pollutants, but the location areas of these three peak regions occupy only 10.7% of all the Lake Nanhu collection area. It was calculated by Dillon model that the TN capacity of the lake is 315.2 t/a and the TP capacity is 21.01 t/a. Under the circumstance of 60% TN and 75% TP removal from sediment release and domestic sewage interception, 67% TN and 87% TP removal from surface runoff pollution are reduced, the TN and TP emission can be controlled below the water environment capacity and their concentration can reach 1.5mg/L and 0.1mg/L respectively. After then, water quality of Lake Nanhu will generally meet the requirements of Class IV.