三峡库区汉丰湖水体CO_(2)及CH_(4)排放特征及影响因素  

Spatial-temporal dynamics and influencing factors of CO_(2) and CH_(4) fluxes in a double-water-level regulated Hanfeng Lake in the Three Gorges Reservoir

作　　者：蹇陈 杨艺 刘婷婷 龚小杰 王晓锋 JIAN Chen;YANG Yi;LIU Ting-ting;GONG Xiao-jie;WANG Xiao-feng(College of Geography and Tourism,Chongqing Normal University,Chongqing 401331,China;Chongqing Key Laboratory of Carbon Cycle and Carbon Regulation of Mountain Ecosystem,Chongqing 401331,China;Chongqing Field Observation and Research Station of Earth Surface Ecological Process in the Three Gorges Reservoir Area,Chongqing 405400,China;Institute of Estuarine and Coastal Sciences,East China Normal University,Shanghai 200241,China)

机构地区：[1]重庆师范大学地理与旅游学院,重庆401331 [2]山区生态系统碳循环与碳调控重庆市重点实验室,重庆401331 [3]三峡库区地表生态过程重庆市野外科学观测研究站,重庆405400 [4]华东师范大学河口海岸科学研究院,上海200241

出　　处：《中国环境科学》2024年第12期7046-7062,共17页China Environmental Science

基　　金：国家自然科学基金资助项目(32371680);重庆市自然科学基金资助项目(2022NSCQ-MSX2598);重庆市教委研究项目(KJQN202200536,KJZD-K202000502);大学生创新创业训练计划项目(202210637007)。

摘　　要：利用漂浮箱法与顶空平衡法对汉丰湖水体CO_(2)与CH_(4)排放通量及溶存浓度进行逐月观测,探讨了其时空特征及影响因素.结果表明:汉丰湖水体CO_(2)排放通量为-64.3~128.4mmol/(m^(2)·d),平均值为(35.8±45.2)mmol/(m^(2)·d),远低于三峡库区其他水域的排放水平,是CO_(2)的排放弱源;CH_(4)通量平均值为(3.87±5.08)mmol/(m^(2)·d),尽管变异性强(0.43~36.93mmol/(m^(2)·d)),但平均水平远高于三峡其他水域,是大气CH_(4)排放的强源;汉丰湖水域每年向大气排放CO_(2)和CH_(4)总量分别为1415.48和133.54t,占汉丰湖水体碳总储量的26.86%,是一个活跃的碳代谢水域.汉丰湖CO_(2)排放通量自1~12月呈先显著降低后迅速升高的季节模式,CH_(4)呈几乎相反的季节变化,但二者季节动态均受水位调度的强烈干扰.三峡高水位期汉丰湖表现为高CO_(2)低CH_(4)排放的特征,汉丰湖水位期则呈低CO_(2)高CH_(4)排放,三峡回水扰动期CO_(2)和CH_(4)排放均较强.相关分析表明,CO_(2)排放通量主要与Chl-a、藻密度、以及pH值等呈显著负相关关系,水体藻类繁殖导致初级生产的变化是主导CO_(2)排放季节动态的关键,导致水体出现明显的CO_(2)源-汇转变,CH_(4)排放通量与水体TOC、DOC、TN、NO_(3)^(-)-N、藻密度等呈显著正相关关系,表明水体养分积累以及藻类代谢共同主导了CH_(4)排放的季节动态.汉丰湖CO_(2)排放通量呈自上游向下游先降低后升高的空间分异,而CH_(4)相反,这种空间分异受到汉丰湖入库河流的汇入及水位调度的共同影响.总之,水位调度明显干扰了水环境参数与碳排放的关联关系,导致不同水位期CO_(2)和CH_(4)排放通量的关键指示因子不同.This study investigated the fluxes and concentrations of CO_(2) and CH_(4) in Hanfeng Lake,using the floating chamber method and headspace equilibrium method,to reveal spatio-temporal dynamics and driving factors of CO_(2) and CH_(4) emissions under varing water level fluctuations.The results showed that Hanfeng Lake was a weak CO_(2) emission source,with a flux range of-64.34to 128.37mmol/(m^(2)·d) and an average of (35.8±45.2)mmol/(m^(2)·d),which was much lower than that of other waters in the Three Gorges Reservoir.Meanwhile,Hanfeng Lake was a strong CH_(4) emission source.Although the CH_(4) flux showed strong variations with ranges of 0.43~36.93mmol/(m^(2)·d),its average value ((3.87±5.08)mmol/(m^(2)·d)) was much higher than that of other regions in the Three Gorges Reservoir.The total emissions of CO_(2) and CH_(4) emitted to the atmosphere by Hanfeng Lake was 1415.48 and 133.54t,respectively,accounting for 26.86%of the total carbon storage of Hanfeng Lake,which indicated that Hanfeng Lake had an active carbon metabolism.From January to December,the CO_(2) emission flux in Hanfeng Lake showed a seasonal pattern of significant decrease and then rapid increase,and CH_(4) showed an almost opposite seasonal change.The seasonal dynamics were strongly disturbed by the double-water-level regulation.Higher CO_(2) and lower CH_(4) emission during the high water level period of the Three Gorges.During the Hanfeng water level period,CO_(2) emission was weaker,but CH_(4) emission was stronger.CO_(2) and CH_(4) emissions were stronger during the Three Gorges backwater period.Correlation analysis showed that CO_(2) emission flux was negatively correlated with Chl-a,algal density and pH.The change of primary production caused by algae blooms was the key factor to dominate the seasonal dynamics of CO_(2) emissions,and even led to the obvious CO_(2) source-sink transition in Hanfeng Lake.CH_(4fluxes) were positively correlated with TOC,DOC,TN,NO_(3)~--N and algal density,indicating that the seasonal dynamics of CH_(4e

关 键 词：汉丰湖 双重水位调节 CO_(2)与CH_(4)排放 时空动态 影响因素 

分 类 号：X511[环境科学与工程—环境工程] X524