Methane emission through ebullition from an estuarine mudflat: 2. Field observations and modeling of occurrence probability: EBULLITION FROM AN ESTUARINE MUDFLAT
Methane emission through ebullition from an estuarine mudflat: 2. Field observations and modeling of occurrence probability: EBULLITION FROM AN ESTUARINE MUDFLAT
复制标题
河口泥滩沸腾产生的甲烷排放：2. 现场观测和发生概率建模：河口泥滩沸腾
DOI：
10.1002/2016wr019720
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发表时间：
2017
影响因子：
5.4
通讯作者：
Slater, Lee
中科院分区：
文献类型：
--
作者：
Chen, Xi;Schäfer, Karina V.;Slater, Lee
在湿地土壤和沉积物中，沸腾可以以比其他途径快得多的速率传输甲烷（CH4），尽管时间和面积有限。然而，现场观测存在很大的不确定性，需要统计模型来描述沸腾发生概率与水位变化之间的函数关系。在河口温带沼泽的泥滩中设计并安装了一个流通室。CH4浓度信号沸腾事件的增加在退潮期间观察到（15个事件超过456退潮），偶尔在涨潮期间（4个事件超过455涨潮）。利用逻辑回归分析确定了沸腾发生函数，发现相对初始水位和相对终止水位以及潮汐振幅是与沸腾事件相关的关键函数变量。沸腾的甲烷是限制在冬季的表面冻结层，这一层融化在春季解冻引起的CH4浓度增加，沸腾通量类似于与大波动的水位周围的大潮。我们的研究结果表明，初始和结束的相对水位，除了潮汐振幅，部分调节沸腾事件在潮汐湿地，调制的月球周期，在不同深度的气泡存储和季节性变化的表面冻结层。几天内的最大潮汐强度，而不是每小时的水位，可能与沸腾发生的可能性更密切相关，因为它代表了每小时和月球周期之间的权衡时间尺度。
Ebullition can transport methane (CH4) at a much faster rate than other pathways, albeit over limited time and area, in wetland soils and sediments. However, field observations present large uncertainties in ebullition occurrences and statistic models are needed to describe the function relationship between probability of ebullition occurrence and water level changes. A flow‐through chamber was designed and installed in a mudflat of an estuarine temperate marsh. Episodic increases in CH4concentration signaling ebullition events were observed during ebbing tides (15 events over 456 ebbing tides) and occasionally during flooding tides (4 events over 455 flooding tides). Ebullition occurrence functions were defined using logistic regression as the relative initial and end water levels, as well as tidal amplitudes were found to be the key functional variables related to ebullition events. Ebullition of methane was restricted by a surface frozen layer during winter; melting of this layer during spring thaw caused increases in CH4concentration, with ebullition fluxes similar to those associated with large fluctuations in water level around spring tides. Our findings suggest that initial and end relative water levels, in addition to tidal amplitude, partly regulate ebullition events in tidal wetlands, modulated by the lunar cycle, storage of gas bubbles at different depths and seasonal changes in the surface frozen layer. Maximum tidal strength over a few days, rather than hourly water level, may be more closely associated with the possibility of ebullition occurrence as it represents a trade‐off time scale in between hourly and lunar periods.