近20年长江中游监利—汉口河段氮、磷负荷时空变化特征分析  

Tempo-spatial Variations in Nitrogen and Phosphorus Loads in Jianli-Hankou Reach of the Middle Yangtze River During the Past 20 Years

作　　者：毛禹 夏军强[1] 周美蓉[1] 邓珊珊[1] MAO Yu;XIA Jun-qiang;ZHOU Mei-rong;DENG Shan-shan(State Key Laboratory of Water Resources Engineering and Management,Wuhan University,Wuhan 430072,China)

机构地区：[1]武汉大学水资源工程与调度全国重点实验室,武汉430072

出　　处：《环境科学》2024年第9期5204-5213,共10页Environmental Science

基　　金：国家自然科学基金项目(U2040215,U2240206,52109098)。

摘　　要：氨氮(NH_(4)^(+)-N)和总磷(TP)属于长江流域重点管控污染物.基于2003~2020年实测水质数据,分析长江中游监利至汉口河段NH_(4)^(+)-N和TP浓度及通量的时空变化,研究水沙因素和支流入汇等对污染物通量变化的影响,结果表明:①近年来干流NH_(4)^(+)-N和TP浓度降低明显,2020年二者较2003年各断面平均减幅为41%和34%;沿程上NH_(4)^(+)-N和TP浓度均先降低后升高.由支流洞庭湖及汉江入汇的NH_(4)^(+)-N和TP浓度整体低于干流;干流二者多年均值均为0.12 mg·L^(−1),支流入汇的则为0.11 mg·L^(−1)和0.09 mg·L^(−1).②通过上、下游断面通量差扣除支流入汇贡献后,NH_(4)^(+)-N和TP通量在监利—螺山段沿程损失,在螺山—汉口段沿程增加.在监利—螺山段,与侧向入流(如洞庭湖)的NH_(4)^(+)-N和TP浓度偏低从而造成该段NH_(4)^(+)-N和TP浓度降低有关,在螺山—汉口段则相反且该段水量、沙量沿程增加.整个监利—汉口河段TP通量和水量、沙量总体增加,而NH_(4)^(+)-N通量显著减少应归因于长江地区以NH_(4)^(+)-N为主的污染物减排政策.③相关性分析结果表明,NH_(4)^(+)-N通量与NH_(4)^(+)-N浓度的相关性最好,而与流量及与输沙率无明显相关,反映研究段NH_(4)^(+)-N主要受点源控制;TP通量与流量及与输沙率的相关性在高流量时期相对较好,而其与TP浓度的相关程度在低流量时期更高,反映枯水期点源排放对TP贡献较丰水期增大.Ammonia nitrogen(NH_(4)^(+)-N)and total phosphorus(TP)were the major control pollutants in the Yangtze River Basin.Based on measured data from 2003 to 2020,the temporal and spatial variations in concentrations and fluxes of NH_(4)^(+)-N and TP in the Jianli to Hankou(JL-HK)reach of the Middle Yangtze River were studied,and the impacts of flow-sediment factors,tributary inflows,and others on variations in NH_(4)^(+)-N and TP fluxes were discussed.The results showed that:①In recent years,NH_(4)^(+)-N and TP concentrations in the mainstream have declined significantly,with annual NH_(4)^(+)-N and TP concentrations at each monitoring station in 2020 averagely decreasing by 41%and 34%compared to those in 2003,respectively.Spatially,NH_(4)^(+)-N and TP concentrations decreased and then increased along the mainstream.NH_(4)^(+)-N and TP concentrations of tributary inflows,which include the Dongting Lake and Han River,were generally lower than that of the mainstream.The multi-year average values of NH_(4)^(+)-N and TP concentrations were both averaged at 0.12 mg·L^(−1) in the mainstream and were averaged at 0.11 mg·L^(−1) and 0.09 mg·L^(−1) in the tributary inflows.②The flux differences between the upper and lower sections net of tributary confluences showed that NH_(4)^(+)-N and TP fluxes were lost in the Jianli to Luoshan(JL-LS)sub-reach and increased in the Luoshan to Hankou(LS-HK)sub-reach in most years.NH_(4)^(+)-N and TP fluxes decreased in the JL-LS sub-reach,which was related to the lower NH_(4)^(+)-N and TP concentrations in lateral inflows,such as Dongting Lake,and thus lowered the NH_(4)^(+)-N and TP concentrations in the mainstream.The LS-HK sub-reach showed the opposite trends,and the water and sediment loads increased in this sub-reach.Across the whole JL-HK reach,TP flux as well as water and sediment loads were recharged along the reach,whereas NH_(4)^(+)-N flux was reduced greatly,which could be attributed to the pollution abatement conducted in the Yangtze River Basin,which mainly focused on

关 键 词：长江 氮、磷浓度 氮、磷通量 时空变化 水沙 

分 类 号：X522[环境科学与工程—环境工程]