Unsaturated hydraulic properties of Sphagnum moss and peat reveal trimodal pore‐size distributions
Unsaturated hydraulic properties of Sphagnum moss and peat reveal trimodal pore‐size distributions
复制标题
泥炭藓和泥炭的不饱和水力特性揭示了三峰孔径分布
DOI：
10.1002/2016wr019707
复制
发表时间：
2017
影响因子：
5.4
通讯作者：
W. Durner
中科院分区：
文献类型：
--
作者：
T. Weber;S. Iden;W. Durner
在湿润泥炭地，水分含量的渗流带（acrotelm）控制氧气扩散速率，氧化还原状态，和营业额的有机质。因此，泥炭地是作为大气碳的汇还是源取决于碳饱和流动过程。理查兹方程是土壤中水流的标准模型，但尚不清楚它是否可以应用于模拟活泥炭藓中的水流。瞬态实验室蒸发实验进行了观察蒸发水通量的acrotelm，含有活泥炭藓，和更深的一层含有分解的苔藓泥炭。通过使用理查兹方程作为非饱和流的过程模型的逆建模来评估实验数据。测试了蒸发过程中的水通量和测量压头的时间序列是否可以模拟。结果表明，只要水力特性用合适的模型表示，测量值可以很好地匹配。为此，有必要对潜在的孔隙大小分布进行三峰参数化，这反映了泥炭藓的三种不同的孔隙系统，由植物间、植物内和植物内部水组成。虽然传统的货车vanchten-Mualem模型导致了很大的差异，但物理上更全面的Peters-Durner-Iden模型（考虑了毛细管和非毛细管流动）导致了对观察结果的更一致的描述。我们的结论是，理查兹方程是一个有效的过程描述在很宽的压力范围内的泥炭地支持的概念化的活苔藓作为包气带的一部分，湿饱和水分通量。
In ombrotrophic peatlands, the moisture content of the vadose zone (acrotelm) controls oxygen diffusion rates, redox state, and the turnover of organic matter. Whether peatlands act as sinks or sources of atmospheric carbon thus relies on variably saturated flow processes. The Richards equation is the standard model for water flow in soils, but it is not clear whether it can be applied to simulate water flow in live Sphagnum moss. Transient laboratory evaporation experiments were conducted to observe evaporative water fluxes in the acrotelm, containing living Sphagnum moss, and a deeper layer containing decomposed moss peat. The experimental data were evaluated by inverse modeling using the Richards equation as process model for variably‐saturated flow. It was tested whether water fluxes and time series of measured pressure heads during evaporation could be simulated. The results showed that the measurements could be matched very well providing the hydraulic properties are represented by a suitable model. For this, a trimodal parametrization of the underlying pore‐size distribution was necessary which reflects three distinct pore systems of the Sphagnum constituted by inter‐, intra‐, and inner‐plant water. While the traditional van Genuchten‐Mualem model led to great discrepancies, the physically more comprehensive Peters‐Durner‐Iden model which accounts for capillary and noncapillary flow, led to a more consistent description of the observations. We conclude that the Richards equation is a valid process description for variably saturated moisture fluxes over a wide pressure range in peatlands supporting the conceptualization of the live moss as part of the vadose zone.
影响因子：
6.4
作者：
A. Peters;S. Iden;W. Durner
通讯作者：
A. Peters;S. Iden;W. Durner
影响因子：
9.8
作者：
Clark, J. M.;Bottrell, S. H.;Chapman, P. J.
通讯作者：
Chapman, P. J.
影响因子：
18.3
作者：
Fenner, Nathalie;Freeman, Chris
通讯作者：
Freeman, Chris