太湖流域上游水源性水库水体脱氮潜力时空变化特征及其管理意义——以天目湖沙河水库为例  

Spatial and temporal differences of nitrogen removal potential by denitrification and its management implications of water-based reservoirs in the upper reaches of Taihu Basin:A case study of Lake Tianmuhu

作　　者：王子聪 许海[1] 朱广伟[1] 朱慧 张铮惠 Wang Zicong;Xu Hai;Zhu Guangwei;Zhu Hui;Zhang Zhenghui(State Key Laboratory of Lake and Environment,Nanjing Institute of Geography&Limnology,Chinese Academy of Sciences,Nanjing 210008,P.R.China;School of Environmental and Civil Engineering,Jiangnan University,Wuxi 214122,P.R.China;Wuxi River and Lake Management and Water Resources Management Center,Jiangsu Province,Wuxi 214031,P.R.China)

机构地区：[1]中国科学院南京地理与湖泊研究所,湖泊与环境国家重点实验室,南京210008 [2]江南大学环境与土木工程学院,无锡214122 [3]江苏省无锡市河湖治理和水资源管理中心,无锡214031

出　　处：《湖泊科学》2024年第1期112-122,共11页Journal of Lake Sciences

基　　金：国家自然科学基金项目(42271126,U22A20561);江苏省科技厅项目(BK20220041);中国科学院南京地理与湖泊研究所自主部署科研项目(NIGLAS2022GS03)联合资助。

摘　　要：氮是湖库富营养化的重要影响因子,水体溶解性氮气饱和度在一定程度上指征着水体的脱氮潜力。为探究太湖流域上游水源型水库脱氮潜力的时空变化特征,该研究选择天目湖沙河水库为研究对象,于2021年2月2022年1月进行了为期一周年的逐月监测,采集不同点位分层水样,利用膜接口质谱仪结合氮氩比法测定水体溶解性氮气浓度,并计算氮气饱和度。结果显示,沙河水库年均氮气饱和度为0.997,总体处于氮饱和状态(氮气饱和度为1),从季节上看,除冬季外,水体氮气饱和度几乎均>1,且随着温度的升高氮气饱和度也升高;空间上,表现为下游>中游>上游,底层>表层,即下游以及底层沉积物表现出更强的脱氮能力。线性回归分析表明,潜在脱氮速率与氮气饱和度拟合效果较好,表明氮气饱和度在一定程度上可以反映沙河水库的脱氮速率;相关性分析与逐步多元线性回归分析显示,氮气饱和度与总氮呈显著正相关,与溶解氧浓度呈显著负相关,说明合适的环境条件有利于脱氮作用的进行,进而使得水体溶解性氮气过饱和。7月极端的降雨与采样前连续的高温天气使得该月成为夏秋季溶解氮气均过饱和的例外,氮气饱和度与水温也失去统计上的相关。在溶解氮气普遍过饱和的夏秋季节,脱氮过程使得水体氮浓度较低,藻类生长受到氮限制,在该期间应积极控氮以限制藻类生长,抑制水华的发生。Nitrogen is anelement causing lake and reservoir eutrophication.The saturation conditions of dissolved N_(2) in water more or less represents the nitrogen removal ability of a lake/reservoir.To understand spatio-temporal variations of nitrogen removal potential by denitrification in reservoirs,Shahe Reservoir(drinking water reservoir)in southeastern China was selected as the study area.Water samples at different depths were collected monthly from February 2021 to January 2022,and their dissolved N_(2) concentration was measured by membrane interface mass spectrometry and nitrogen and argon ratio method(N_(2)∶Ar).The N_(2) saturation were then calculated.The results showed that the annually averaged N_(2) saturation in Shahe Reservoir was 0.997,i.e.,close to saturation with a value of 1.In spring,summer and autumn,N_(2) saturation were generally higher than 1,and was positively related to water temperature.Spatially,N_(2) saturation showed a pattern of downstream>midstream>upstream,and bottom water>surface water.This pattern implied that the downstream area and the bottom sediment had a stronger nitrogen removal ability.Linear regression analysis showed that the potential nitrogen removal rate fitted well with N_(2) saturation,implying that N_(2) saturation could reflect the nitrogen removal rate.Correlation analysis and stepwise multiple linear regression analysis showed that N_(2) saturation was significantly positively correlated with total nitrogen,and negatively correlated with dissolved oxygen concentration.These results revealed nitrogen removal depended on environmental conditions,and caused supersaturated with dissolved N_(2) of reservoir water.The extreme rainfall and the continuing high temperature in July resulted in an unclear relationship between N_(2) saturation and water temperature.In the summer and autumn with supersaturated conditions of dissolved N_(2),nitrogen removal via denitrification led to low nitrogen concentration in water,and thus limited algae growth.During this period,the nitrogen

关 键 词：富营养化 水库 反硝化作用 固氮作用 N_(2)∶Ar 

分 类 号：X524[环境科学与工程—环境工程]