三峡水库重庆主城段汛期水-气界面CO_(2)与CH4通量变化及其影响因素  

CO_(2)and CH4 Fluxes Variation across Water-Air Interface and Influencing Factors in Chongqing’s Central Urban Area of the Three Gorges Reservoir During the Flood Season

作　　者：秦宇[1] 李银波 张媛媛 鲁伦慧[2] QIN Yu;LI Yinbo;ZHANG Yuanyuan;LU Lunhui(College of River and Ocean Engineering,Chongqing Jiaotong University,Chongqing 400074,China;Chongqing Institute of Green and Intelligent Technology,Chinese Academy of Sciences,Chongqing 400714,China)

机构地区：[1]重庆交通大学河海学院,重庆400074 [2]中国科学院重庆绿色智能技术研究院,重庆400714

出　　处：《武汉大学学报（理学版）》2024年第1期27-38,共12页Journal of Wuhan University:Natural Science Edition

基　　金：国家自然科学基金(42107273);水利部重大计划项目(SKS-2022081);重庆市研究生联合培养基地项目(JDLHPYJD2018001)。

摘　　要：三峡水库重庆主城段位于三峡水库的变动回水区,具有天然河道和水库的双重特性,温室气体排放特征相关研究不足。为探究三峡水库重庆主城段水-气界面二氧化碳(CO_(2))、甲烷(CH_(4))通量变化及其影响因素,本研究于2020年6月、9月在三峡水库重庆主城段李家沱、大溪沟、寸滩、唐家沱、郭家沱分别采集表层、底层水样,运用薄边界层模型法估算水-气界面CO_(2)、CH_(4)通量,采用δ^(13)C、N/C及同位素多元混合源解析模型研究颗粒有机碳(POC)来源及其贡献率。结果表明,研究期间三峡水库重庆主城段水-气界面CO_(2)、CH_(4)通量均表现为“源”的特征,CO_(2)通量6月(1880.25±366.75μmol·m^(-2)·h^(-1))显著高于9月(992.74±225.27μmol·m^(-2)·h^(-1)),CH_(4)通量9月(3.55±0.36μmol·m^(-2)·h^(-1))显著高于6月(2.26±0.59μmol·m^(-2)·h^(-1))。另外,水体δ^(13)C-POC的变化范围为-24.27‰~-26.67‰,月份间无明显差异;水体POC主要来自陆源(72±13)%,其次是自源(25±13)%。影响该区域水-气界面CO_(2)、CH_(4)通量的主要因素分别为水体溶解性无机碳(DIC)和颗粒有机碳(POC),2020年8月陆源输入的大量异源性有机碳(OC)成为该时期CH_(4)通量较高的原因。The central urban section of Chongqing within the Three Gorges Reservoir is located in the fluctuating backwater area,which exhibits the dual characteristics of a natural river and a reservoir.However,the understanding of its greenhouse gas emis⁃sions remains insufficient.To investigate the changes of carbon dioxide(CO_(2))and methane(CH_(4))fluxes at the water-air interface,surface and bottom water samples were collected in Lijiatuo,Daxigou,Cuntan,Tangjiatuo and Guojiatuo in Chongqing’s central urban area of the Three Gorges Reservoir in June and September 2020,respectively.The CO_(2)and CH_(4)fluxes at the waterair interface were calculated using the thin boundary layer(TBL)model estimation method.The sources and their contributions of particulate organic carbon(POC)were investigated usingδ^(13)C,N/C and isotope multiple mixed source analysis.The results show that the CO_(2)and CH_(4)fluxes at the water-air interface show“source”characteristics in the study area.The CO_(2)flux(1880.25±366.75μmol·m^(-2)·h^(-1))in June were significantly higher than that in September(992.74±225.27μmol·m^(-2)·h^(-1)),and the CH_(4)fluxes at the water-air interface were significantly higher in September(3.55±0.36μmol·m^(-2)·h^(-1))than that in June(2.26±0.59μmol·m^(-2)·h^(-1)).In addition,the range ofδ^(13)C-POC variation in the aquatic system is from-24.27‰to-26.67‰,with no significant differences observed between months.The POC was mainly from the terrestrial sources(72±13)%,then from the autogenous sources(25±13)%.The main factors affecting the CO_(2)and CH_(4)fluxes at the water-air interface in this region were dissolved inorganic carbon(DIC)and particulate organic carbon(POC)in the water.In August 2020,the large influx of exogenous organic carbon(OC)from terrestrial sources became the main reason for the higher CH_(4)flux.

关 键 词：三峡水库 温室气体 水-气界面通量 稳定同位素 影响因素 

分 类 号：X524[环境科学与工程—环境工程]