Soil heterogeneity effects on O2 distribution and CH4 emissions from wetlands: In situ and mesocosm studies with planar O2 optodes and membrane inlet mass spectrometry
Soil heterogeneity effects on O2 distribution and CH4 emissions from wetlands: In situ and mesocosm studies with planar O2 optodes and membrane inlet mass spectrometry
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DOI：
10.1016/j.soilbio.2010.08.026
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发表时间：
2010-12-01
影响因子：
9.7
通讯作者：
Joensen, Hans R.
中科院分区：
文献类型：
--
作者：
Askaer, Louise;Elberling, Bo;Joensen, Hans R.
通过对特定深度的 O-2 和 CH4 浓度的原位点测量以及对比水位下的同步土壤 CH4 通量来评估土壤异质性对湿地土壤甲烷排放的重要性。剖面测量及其解释中的相关假设在应用平面 O-2 光极和膜入口质谱的受控中生态排水和饱和度实验中得到了验证。结果表明，泥炭土是异质的，含有由大型动物和植物群产生的动态大孔隙系统，有利于水、O-2 和 CH4 的优先流动，并随着湿度状况的变化而暂时变化。排水后地下水位以上的 O-2 含量在几毫米内从 0 % 空气饱和度水平变化到 100% 空气饱和度。在水位变化后长达数天的时间内，在水位以下观察到有氧区域，在水位以上的层中观察到缺氧区域。这项研究表明，虽然地下水位位置是较大时空尺度下土壤 CH4 通量的有效代理，但在较高空间分辨率（即土壤脚及以下尺度）下，它变得不够充分。使用平面 O-2 光极进行高分辨率 O-2 测量具有巨大的潜力，可以增强我们对湿地土壤中几厘米至毫米尺度上地下水位位置对 O-2 动态影响的理解。 (C) 2010 Elsevier Ltd. 保留所有权利。
The importance of soil heterogeneity for methane emission from a wetland soil is assessed by in situ point measurements of depth-specific O-2 and CH4 concentrations and simultaneous soil CH4 fluxes at contrasting water levels. Profile measurements, and associated assumptions in their interpretation, were validated in a controlled mesocosm drainage and saturation experiment applying planar O-2 optodes and membrane inlet mass spectrometry. Results show that peat soil is heterogeneous containing dynamic macropore systems created by both macrofauna and flora, which facilitate preferential flow of water, O-2 and CH4 and vary temporally with changes in the moisture regime. The O-2 content above the water table after drainage varied horizontally from 0 to 100% air saturation within few mm. Oxic zones were observed below the water level and anoxic zones were observed in layers above the water level in periods up to days after changes in the water level. This study shows that although water table position is a competent proxy of soil CH4 fluxes at larger spatio-temporal scales, it becomes inadequate at higher spatial resolution, i.e. at the scale of the soil pedon and below. High resolution O-2 measurements using planar O-2 optodes have great potential to enhance our understanding of the effect of the water table position on O-2 dynamics on scales of several cm to mm in wetland soils. (C) 2010 Elsevier Ltd. All rights reserved.