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引用本文:陈敏,许浩霆,郑祥旺,虞之锋,肖尚斌.夏季降雨事件对水库温室气体通量变化的影响:来自湖北官庄水库的高频观测.湖泊科学,2021,33(6):1857-1870. DOI:10.18307/2021.0619
Chen Min,Xu Haoting,Zheng Xiangwang,Yu Zhifeng,Xiao Shangbin.Impacts of summer rainfall events on the dynamics of greenhouse gas fluxes revealed by high-frequency observation from Guanzhuang Reservoir, Hubei Province. J. Lake Sci.2021,33(6):1857-1870. DOI:10.18307/2021.0619
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夏季降雨事件对水库温室气体通量变化的影响:来自湖北官庄水库的高频观测
陈敏1,2, 许浩霆1, 郑祥旺1, 虞之锋1, 肖尚斌1,2
1.三峡大学水利与环境学院, 宜昌 443002;2.三峡库区生态环境教育部工程研究中心, 宜昌 443002
摘要:
湖库淡水水域对温室气体排放的贡献不容小觑,然而观测时间的代表性不足以及缺乏对降雨因素的考虑制约了碳排放的准确估计.本研究以湖北宜昌境内官庄水库为例,选取强降雨多发的夏季时段,针对水气界面温室气体通量、水体表层和垂向剖面气体溶存浓度及环境因子开展了为期1周的原位高频观测,以探讨夏季降雨事件对水库温室气体通量变化的影响.结果表明,观测期内官庄水库水气界面CH4通量变化范围为0.007~0.077 mg/(m2·h),CO2通量范围为5.48~57.57 mg/(m2·h),白天和夜晚均表现为大气的碳源.小雨、中雨乃至暴雨天气条件下,CH4和CO2日均通量均较低,日通量倾向于受风速和温度调控.CH4和CO2通量变化趋势较为一致,观测期内日间排放量高于夜间排放量出现的次数更多,昼夜差异对降雨天气状况无明显响应,风速是CH4和CO2通量昼夜变化的主导因素.暴雨过程中,CH4-k600和CO2-k600与水气温差存在显著正相关,但水体垂向混合过程十分短暂.在平均雨强为3.8 mm/h的暴雨第I阶段,CH4-k600对风速和降雨的响应明显,而在雨强更大(8.5 mm/h)的第II阶段,CH4-k600与风速、降雨均未表现出相关性,通量箱在强降雨条件下的适用性可能存在雨强阈值.
关键词:  甲烷  二氧化碳  排放通量  昼夜变化  暴雨  官庄水库
DOI:10.18307/2021.0619
分类号:
基金项目:国家自然科学基金项目(41807513,51979148)和湖北省自然科学基金创新群体项目(2019CFA032)联合资助.
Impacts of summer rainfall events on the dynamics of greenhouse gas fluxes revealed by high-frequency observation from Guanzhuang Reservoir, Hubei Province
Chen Min1,2, Xu Haoting1, Zheng Xiangwang1, Yu Zhifeng1, Xiao Shangbin1,2
1.College of Hydraulic and Environmental Engineering, China Three Gorges University, Yichang 443002, P. R. China;2.Engineering Research Center of Eco-environment in Three Gorges Reservoir Region, Yichang 443002, P. R. China
Abstract:
Lakes and reservoirs are recognized to significantly contribute to global emissions of greenhouse gases, but unrepresentative sampling periods and a lack of consideration of rainfall conditions have limited the accurate estimation of carbon emission. This study took the Guanzhuang Reservoir in Yichang, Hubei Province, as an example, selecting summertime which has more frequently intense precipitation. In-situ high-frequency observations of greenhouse gas fluxes at the air-water interface, dissolved gas concentrations and environmental variables at the surface and over the vertical profile were implemented for a week, to investigate the impacts of summer rainfall events on the dynamics of greenhouse gas fluxes. Results showed that CH4 flux ranged between 0.007 and 0.077 mg/(m2·h), and CO2 flux was from 5.48 to 57.57 mg/(m2·h) at the air-water interface of the Guanzhuang Reservoir during the monitoring period, indicating a net source of carbon to the atmosphere during both day and night. Under light rain, moderate rain, and even storm conditions, daily average fluxes of both CH4 and CO2 appeared to be relatively low. Daily fluxes tended to be regulated by wind speed and temperature. CH4 and CO2 fluxes exhibited similar trends of variation, and daytime flux>nighttime flux was more often detected during the observation period. Difference between daytime and nighttime fluxes was not influenced by rainy weather conditions, but wind speed was the dominant factor affecting diurnal variations of CH4 and CO2 fluxes. During the storm event, CH4-k600 and CO2-k600 were significantly positively correlated with the temperature difference between water and air, but the convective mixing was in a very short time. At phase Ⅰ of the storm with an average rainfall intensity of 3.8 mm/h, CH4-k600 responded to wind speed and rainfall significantly. While during phase Ⅱ of the storm with a higher rainfall intensity (8.5 mm/h), CH4-k600 was not correlated with wind speed and rainfall. It suggested that there might be a threshold value of rainfall intensity for the applicability of floating chambers under intense rainfall conditions.
Key words:  Methane  carbon dioxide  emission flux  diel variation  storm  Guanzhuang Reservoir
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