摘要
以宜昌境内喀斯特河流下牢溪为研究对象,通过对流域内15个采样点为期1a间隔约2周1次的水量、水质及CH_(4)浓度同步监测,探讨河流溶存CH_(4)浓度时空变化规律及影响因素.结果表明:下牢溪溶存CH_(4)浓度变化范围为0.002~1.492μmol/L,全年平均浓度0.133μmol/L,整体表现为大气CH_(4)的源.河流溶存CH_(4)浓度呈现夏秋高、冬春低的变化特征,主要受温度驱动.雨季CH_(4)浓度受温度和降雨共同调控.温度越高,产生流量稀释效应的降雨量阈值也越大.下牢溪CH_(4)浓度空间分异性显著,小型拦水坝前浓度最高,最低值出现在河底坡降较大的天然峡谷型河道.人为活动不同程度的提高了相应河段的CH_(4)浓度水平,是小流域CH_(4)浓度空间分布格局的重要影响因素.流域CH_(4)浓度空间分布无明显时间稳定性特征,这可能与陆源输入及水平、垂向输出等动态因素有关,实施全流域采样监测对小型河流碳排放估算十分必要.
This study focused on Xialaoxi,a karst river in Yichang,to explore the temporal and spatial pattern of dissolved methane concentration and its driving factors via biweekly measurements of flow,water quality and methane concentrations at 15 sampling sites in the watershed during a year.Dissolved CH_(4) concentrations ranged between 0.002 and 1.492μmol/L,and the mean concentration was 0.133μmol/L,indicating a net source of methane to the atmosphere.The riverine CH_(4) concentrations were relatively high in summer and autumn while lower in winter and spring,which was mainly driven by temperature.In wet season,the CH_(4) concentration was jointly regulated by temperature and precipitation.The higher the temperature,the larger the threshold value of rainfall that could trigger the flow dilution effect.There was significant spatial heterogeneity in riverine CH_(4) concentration,with the highest value observed in front of small dams,while the lowest in the natural canyon reach with a large bed slope.Human activities led to varying degrees of increase in riverine CH_(4) concentration of relevant reaches.It was recognized as an important factor controlling the spatial pattern of dissolved CH_(4) concentration in the small watershed.The spatial distribution of CH_(4) concentration did not show significant temporal stability,which may be related to dynamics involved in processes of terrestrial inputs,horizontal and vertical outputs and so on.Accordingly,measurements across the whole watershed shall be necessary for an accurate estimation of carbon emission from a small river.
作者
许浩霆
陈敏
肖尚斌
虞之锋
梁爽
郑祥旺
XU Hao-ting;CHEN Min;XIAO Shang-bin;YU Zhi-feng;LIANG Shuang;ZHENG Xiang-wang(College of Hydraulic and Environmental Engineering,China Three Gorges University,Yichang 443002,China;Engineering Research Center of Eco-environment in Three Gorges Reservoir Region,Yichang 443002,China;Hubei Field Observation and Scientific Research Stations for Water Ecosystem in Three Gorges Reservoir,Yichang 443002,China)
出处
《中国环境科学》
EI
CAS
CSCD
北大核心
2021年第8期3758-3766,共9页
China Environmental Science
基金
国家自然科学基金资助项目(41807513,51979148)
湖北省自然科学基金创新群体资助项目(2019CFA032)。
关键词
小流域
河流
CH_(4)
溶存浓度
时空变化
small watershed
river
methane
dissolved concentration
temporal and spatial variation
作者简介
许浩霆(1996-),男,四川西昌人,三峡大学硕士研究生,主要研究方向为淡水生态系统碳循环.发表论文3篇;责任作者:陈敏,讲师,minchen@ctgu.edu.cn;责任作者:肖尚斌,教授,shangbinx@163.com。
