Evolution of biogenic gases in peat blocks inferred from noninvasive dielectric permittivity measurements
Evolution of biogenic gases in peat blocks inferred from noninvasive dielectric permittivity measurements
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通过无创介电常数测量推断泥炭块中生物气体的演化
DOI：
10.1029/2006wr005562
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发表时间：
2007
影响因子：
5.4
通讯作者：
L. Slater
中科院分区：
文献类型：
--
作者：
X. Comas;L. Slater
泥炭地含有产甲烷古生菌，负责产生大量的游离相生物气体（例如甲烷和二氧化碳），但关于这些气体在土壤基质中的形成机制和空间分布仍然存在相当大的不确定性。我们证明了一种新的方法来记录非侵入性的演变，空间分布和排放模式的生物气体在泥炭土的有效性。从缅因州的大型淡水泥炭地中提取泥炭块（0.022 m3）。无创测量块的多个切片的体介电常数（1.2 GHz）（1）当温度从5°C增加到21°C时增加2°C d−1，以及（2）在随后的2个月期间，温度保持恒定在21 ± 1°C。分别使用便携式甲烷检测器和表面高程杆网格同时监测表面的甲烷排放和泥炭表面变形。我们的研究结果表明：（1）测量电磁波穿越泥炭块的走时提供了一个独特的方法，（并且当与表面变形测量相比时更准确）监测泥炭块内的气体动力学和空间气体分布而不干扰天然气状况的方式;（二）在我们的实验条件下，沸腾似乎优先发生在近地表泥炭，并显示出与大气变化的一些对应关系。压力;（3）沸腾通量具有一定的周期性，这表明它是可预测和可量化的，这将有助于气候模拟工作。我们的研究结果是一致的，与以前的研究的基础上，在泥炭土中的气体动力学（包括气体体积和通量与生物气体沸腾）。
Peatlands contain methanogenic archea responsible for generating significant amounts of free‐phase biogenic gases (for example, methane and carbon dioxide), but considerable uncertainty still exists regarding the mechanisms of formation and spatial distribution of these gases within the soil matrix. We demonstrate the effectiveness of a new method to record noninvasively the evolution, spatial distribution, and emission patterns of biogenic gases in a peat soil. A peat block (0.022 m3) was extracted from a large freshwater peatland in Maine. The bulk dielectric permittivity (at 1.2 GHz) for multiple slices of the block was measured noninvasively (1) as temperature was increased 2°C d−1 from 5°C to 21°C, and (2) for a subsequent 2‐month period during which temperature was held constant at 21 ± 1°C. Methane emissions at the surface and peat surface deformation were monitored concurrently using a portable methane detector and a grid of surface elevation rods, respectively. Our results demonstrate that (1) the measurement of electromagnetic wave traveltimes across a peat block offers a unique (and more accurate when compared to surface deformation measurements) way to monitor gasdynamics and spatial gas distribution within a peat block without any disturbance to the natural gas regime; (2) the ebullition under our experimental conditions seems to preferentially occur from the near‐surface peat and shows some correspondence with changes in atmospheric pressure; and (3) the ebullition flux exhibits periodicity, suggesting that it may be predictable and quantifiable, which could assist climate modeling efforts. Our findings are consistent with previous studies based on gasdynamics in peat soils (including gas volumes and fluxes associated with biogenic gas ebullition).