强降雨对北运河流域沙河水库水质的影响

Impacts of heavy rainfall on the water quality of Shahe Reservoir in the North Canal Basin

随着北运河点源污染逐步得到有效治理,汛期面源污染成为北运河水质不达标的主要影响因素,而现阶段有关强降雨对北运河上游水质的影响研究尚匮乏.本文以北运河上游沙河水库为研究对象,开展了单场强降雨对北运河上游水质的影响研究.在强降雨后(降雨量达53.8 mm·d^-1)开展连续6 d跟踪采样,并对比强降雨前后该库区的水质监测数据,系统解析了强降雨对北运河上游水质的影响特征.结果表明,库区水质基本达到IV类水质标准(GB3838-2002),总磷是雨后影响库区水质的主要因素.南沙河污染和富营养化程度严重,严重超出IV类水质标准,是主要的汇入污染源.再生水厂出水是库区水质硝态氮的主要贡献来源.汛期单次降水不会引起水质的显著恶化,大部分水质指标于3~4 d后降低,4~6 d逐渐恢复到降雨前水质,并趋于稳定.

Along with effective treatment and control of point source pollution in the North Canal gradually,non⁃point source pollution in flood season has become the main factor affecting the water quality of the North Canal,however there is a lack of research on impacts of heavy rainfall on water quality of the upstream of the North Canal.In this study,Shahe Reservoir in the upstream of the North Canal was select to investigate influence of single heavy rainfall on water quality in the upstreams of the North Canal.Through tracking and sampling for six consecutive days after the heavy rainfall(up to 53.8 mm·d^-1),and comparing water quality data of the region before and after the heavy rainfall,impacts of heavy rainfall on water quality of the upstream of the North Canal were systematically analyzed.The water quality in the reservoir basically reaches level IV,total phosphorus(TP)is the main factor that affects the water quality of the reservoir after rain.The Nansha River has serious pollution and eutrophication,far exceeding the Class IV water quality standard(GB3838—2002),and is the main source of pollution in the reservoir area.The effluent of the sewage treatment plant(STP)has no significant difference after rainfall,which is the main source of nitrate nitrogen contribution to the water quality of the reservoir area.The single precipitation in the flood season will not cause significant deterioration of water quality.Most of the indexes decrease after 3~4 d,and the water quality gradually recovers before rain in 4~6 d,and tends to be stable.