北京市房山区河流水质与营养状态对连通性和再生水补给的响应  

The impact of connectivity and reclaimed water replenishment on river water quality and trophic state in Fangshan District, Beijing

作　　者：刘晟廷 曹宸 景峰 苏静君[1] 李叙勇[1,2] LIU Shengting;CAO Chen;JING Feng;SU Jingjun;LI Xuyong(State Key Laboratory of Urban and Regional Ecology,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,Beijing 100085;University of Chinese Academy of Sciences,Beijing 100049;Ecological Environment Bureau of Liangxi District,Wuxi 214000;China International Engineering Consulting Corporation,Beijing 100048)

机构地区：[1]中国科学院生态环境研究中心,城市与区域生态国家重点实验室,北京100085 [2]中国科学院大学研究生院,北京100049 [3]无锡市梁溪区生态环境局,无锡214000 [4]中国国际工程咨询有限公司,北京100048

出　　处：《环境科学学报》2025年第2期166-176,共11页Acta Scientiae Circumstantiae

基　　金：国家自然科学基金项目(No.42277384);国家重点研发计划(No.2016YFC0503007)。

摘　　要：连通性受损影响河流水文节律,阻碍物质、能量及生物信息流动,加剧河流富营养化风险.再生水补给作为河流生态修复的重要手段,在恢复河流自然连通的同时也可能增加河流富营养化风险,但鲜有研究在流域尺度探讨河流水系连通性和再生水补给的综合作用对水质、富营养化状态的影响.本研究采用改进的阻隔系数法量化河流纵向连通性,以叶绿素a指示河流富营养化程度,构建随机森林响应模型,识别影响河流叶绿素a空间分布的重要因子并探讨其作用机制.结果表明,房山区3条主要河流纵向连通性排序为大石河上游与拒马河>小清河>大石河下游,其中大石河下游因连通性差、水力停留时间长、再生水补给量大而具有最高的叶素绿a水平和富营养化程度.再生水补给促进连通性差的河流中浮游植物聚集生长的可能机制在于其提供了丰富的营养盐(TP>0.2 mg·L^(-1))、适宜的氮磷物质的量的比(20∶1~30∶1)、较低的氨氮总氮比(<20%)和较高的水体温度.随机森林响应模型揭示了总磷、再生水补给量、氨氮总氮比、水温、纵向连通性和流速是影响河流叶绿素a空间分布的重要因素.调控河流流速(>0.2 m·s^(-1))和控制再生水出水的总磷浓度(<0.2 mg·L^(-1))可有效降低再生水补给为非连续河流带来的富营养化风险.本研究对指导缺水地区利用再生水进行生态补水和降低生态风险具有重要的理论应用价值.Reclaimed water replenishment is pivotal in maintaining and promoting river connectivity in arid regions,but if not properly managed,it can lead to exacerbate eutrophication.To date,few studies have investigated the combined effects of river connectivity and reclaimed water supplementation on water quality and eutrophication status at the watershed level.This study examines these impacts in Beijing's Fangshan District,employing an advanced barrier coefficient method to measure river longitudinal connectivity and developing a random forest model with chlorophyll-a(Chl a)as an indicator of trophic status.Our results reveal a connectivity gradient among the main rivers,with the Dashi River's downstream area showing the highest chlorophyll-a levels.This is due to its poor connectivity and substantial inflow of reclaimed water.The introduction of Reclaimed water enhances phytoplankton growth by providing nutrients,such as total phosphorus(TP>0.2 mg·L^(-1)),and optimal growth conditions,including a favorable total nitrogen to phosphorus molar ratio(N/P,20∶1~30∶1),a low ammonia nitrogen to total nitrogen ratio(NH_(3)-N/TN<20%),and suitable water temperatures.The random forest model identified TP,reclaimed water volume,nutrient ratios,water temperature,connectivity,and flow velocity as key factors influencing the spatial distribution of river Chl a. The study concludes that modulating flow velocity (>0.2 m·s^(-1)) and controlling TP concentrations in reclaimed water (<0.2 mg·L^(-1)) are critical for mitigating ecological risks in rivers with low connectivity that are replenished with reclaimed water. These insights are valuable for the sustainable use of reclaimed water in ecological restoration, especially in disconnected rivers within arid regions.

关 键 词：纵向连通性 再生水 河流水质 叶绿素A 富营养化 

分 类 号：X522[环境科学与工程—环境工程]