| 引用本文: | 王雪竹,刘佳,牛凤霞,肖尚斌,陈敏.基于走航高频监测的水库冬季水体溶解甲烷浓度分布:以湖北西北口水库为例.湖泊科学,2021,33(5):1564-1573. DOI:10.18307/2021.0524 |
| Wang Xuezhu,Liu Jia,Niu Fengxia,Xiao Shangbin,Chen Min.Dissolved methane concentration distribution of reservoir in winter based on the underway high-resolution monitoring: A case study of the Xibeikou Reservoir in Hubei Province*. J. Lake Sci.2021,33(5):1564-1573. DOI:10.18307/2021.0524 |
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| 摘要: |
| 水库是大气甲烷（CH4）的重要来源之一，但目前对水库（尤其是河道型水库）中溶解CH4浓度及释放潜力的空间异质性的认识仍不足.为揭示河道型水库冬季溶解CH4浓度的分布规律，于2020年1月在湖北宜昌黄柏河流域内西北口水库采用自主研发的新型快速水-气平衡装置（FaRAGE）连接便携式温室气体分析仪，开展了水体溶解CH4浓度的连续走航式监测及断面垂向监测.根据溶解CH4从库尾至库首的浓度变化可以将水库分为3段：距回水末端1 km内为快速降低段，溶解CH4浓度范围为0.117~0.233 μmol/L；1~6 km内为缓慢降低段，CH4浓度范围为0.055~0.117 μmol/L；6~13 km范围内为浓度平稳段，CH4浓度范围为0.039~0.080 μmol/L.整体上，水库表层水体溶解CH4浓度与表层水温、水深及距回水末端的距离呈显著负相关关系（r=-0.77、-0.89、-0.81；P<0.01），与叶绿素a浓度、溶解氧浓度呈显著正相关性（r=0.95、0.97；P<0.01）.基于当月平均风速，采用薄边界层法估算了上述3段区域的CH4扩散通量，分别为（0.023±0.004）、（0.012±0.003）、（0.007±0.001）mg/（m2·h）.西北口水库在冬季表现为向大气释放CH4的“源”，且由于溶解CH4浓度分布不均而表现出较强的空间差异性. |
| 关键词: 河道型水库 溶解CH4浓度 空间分布 通量 西北口水库 |
| DOI：10.18307/2021.0524 |
| 分类号: |
| 基金项目:国家自然科学基金项目（51979148，41807513）和湖北省自然科学基金创新群体项目（2019CFA032）联合资助. |
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| Dissolved methane concentration distribution of reservoir in winter based on the underway high-resolution monitoring: A case study of the Xibeikou Reservoir in Hubei Province* |
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Wang Xuezhu1, Liu Jia1, Niu Fengxia1, Xiao Shangbin1,2, Chen Min1,2
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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
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| Abstract: |
| Reservoirs are important sources of methane in the atmosphere, but the spatial heterogeneities of dissolved methane concentration (DMC) and its releasing potential in reservoirs (especially channel-type reservoir) are still poorly understood. To reveal the DMC spatial pattern in channel-type reservoirs in winter, we focused on the Xibeikou Reservoir in the Huangbai River Basin, Yichang, Hubei, using our newly-invented fast water-gas balance device (FaRAGE) to connect a portable greenhouse gas analyzer for continuous underway measurements of methane concentrations in surface water as well as vertical profile monitoring in January of 2020. According to the DMC variation in water from the end to the head of the reservoir, the reservoir can be divided into three sections: 1) Within 1 km from the end of the backwater area was the rapid descending section, with DMCs ranging between 0.117 and 0.233 μmol/L; 2) 1-6 km away from the end of backwater area was the slowly decreasing section, with DMCs ranging between 0.055 and 0.117 μmol/L; 3) 6-13 km away from the end of backwater area was the stationary section, and DMCs were from 0.039 to 0.080 μmol/L. On the whole, DMC in surface water of the reservoir exhibited significant negative correlations with the surface water temperature, water depth, and the distance from the end of the backwater area (r=-0.77, -0.89, -0.81; P<0.01), whereas it was significantly positively correlated with chlorophyll-a and dissolved oxygen concentration (r=0.95, 0.97; P<0.01). The methane diffusive fluxes in the three sections were further estimated using the thin boundary layer method based on the monthly average wind speed. They were (0.023±0.004), (0.012±0.003), and (0.007±0.001) mg/(m2·h), respectively. The Xibeikou Reservoir acted as a “source” of the atmospheric methane in winter, and it showed strong spatial differences due to the DMC's uneven distribution. |
| Key words: Channel-type reservoir dissolved methane concentration spatial distribution flux Xibeikou Reservoir |
