摘要
近年来三峡水库支流回水区水华频发,而磷在沉积物中的滞留及释放过程可能是其重要影响因素,因此针对三峡支流沉积物磷开展研究.以三峡水库4条重要支流香溪河、大宁河、草堂河及小江为研究对象,通过沉积物磷赋存形态调查、等温吸附实验等方法评估沉积物磷的释放潜力及其对水质的影响.调查结果表明,香溪河、大宁河、草堂河及小江各河口沉积物ω(TP)分别为634、434、629及689 mg·kg^(-1),其中ω(NaOH-P)分别为69、100、103及115 mg·kg^(-1),与国内主要水库的沉积物磷含量相比,处于中低等水平;空间上,支流汇入干流的河口区沉积物磷含量普遍高于相应支流的上游河段沉积物;等温吸附实验表明,各支流河口区沉积物比上游沉积物具有更高的磷释放潜力,其中小江河口区沉积物磷释放潜力最大;温度升高、溶解氧降低等环境条件改变能显著促进沉积物磷释放,小江河口区沉积物在适宜条件下磷释放速率最大可达0.861 mg·(m^(2)·d)^(-1),这导致水华暴发期该区域底层水体磷浓度显著高于表层水体.综上,目前三峡水库部分支流沉积物在水华易发季节发挥了磷“源”的作用,尤其是小江和香溪河,沉积物磷释放能加速水体磷循环过程.研究结果可为河流型水库内源磷控制及蓝藻水华防控提供科学依据.
In recent years,algal blooms have occurred frequently in the backwater areas of tributaries of the Three Gorges Reservoir.The retention and release of sediment phosphorus might be a key factor,so it is necessary to conduct in-depth research on its impact.This study took the four important tributaries of the Three Gorges Reservoir,the Xiangxi River,Daning River,Caotang River,and Xiaojiang River,as the research object to evaluate the potential release of sediment phosphorus in these tributaries and its impact on water quality,using investigation and incubation experiments.The results showed that the total phosphorus content in sediments at the mouth of the Xiangxi River,Daning River,Caotang River,and Xiaojiang River were 634,434,629,and 689 mg·kg^(-1),respectively.The active phosphorus(NaOH-P)contents in sediment of those four rivers were 69,100,103,and 115 mg·kg^(-1),respectively,which were at medium and lower levels compared with those in major domestic reservoirs.The phosphorus contents in sediments in the river mouth area,where tributaries flowed into the main stream of the Three Gorges,were higher than that of the upstream reaches of the corresponding tributaries.The incubation experiments showed that the sediments in the river mouth area of each tributary had higher phosphorus release potential than sediments in the upstream reaches.Within the four tributaries,the sediments in the Xiaojiang River had the highest phosphorus release ability.The changes in water environmental conditions,such as increased temperature and reduced dissolved oxygen concentration,could significantly promote the phosphorus release rates from sediments.The phosphorus release rate of sediments in Xiaojiang River was the largest,at 0.861 mg·(m^(2)·d)^(-1),which made the dissolved phosphorus concentration in bottom water much higher than in surface water during the algae bloom period.Overall,the sediment in the tributaries of the Three Gorges Reservoir,especially in the Xiaojiang and Xiangxi Rivers,currently played the role as phosphorus“source”during the algal bloom periods,in which phosphorus release from sediments could accelerate the phosphorus cycle in the water body.The results of this study offer a scientific basis for the control of internal phosphorus in river-type reservoirs and the prevention and control of algal blooms.
作者
李燕妮
朱梦圆
权秋梅
朱广伟
许海
施坤
LI Yan-ni;ZHU Meng-yuan;QUAN Qiu-mei;ZHU Guang-wei;XU Hai;SHI Kun(College of Environmental Science and Engineering,China West Normal University,Nanchong 637002,China;State Key Laboratory of Lake Science and Environment,Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences,Nanjing 210008,China)
出处
《环境科学》
北大核心
2025年第12期7634-7646,共13页
Environmental Science
基金
国家自然科学基金联合重点基金项目(U22A20561)
国家自然科学基金项目(42077161)。
关键词
三峡水库
回水区
沉积物
磷
内源释放
Three Gorges Reservoir
backwater area
sediment
phosphorus
internal release
