The hydraulic conductivity of peat with respect to scaling, botanical composition, and greenhouse gas transport: Mini-aquifer tests from the Red Lake Peatland, Minnesota
The hydraulic conductivity of peat with respect to scaling, botanical composition, and greenhouse gas transport: Mini-aquifer tests from the Red Lake Peatland, Minnesota
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泥炭的水力传导率与结垢、植物成分和温室气体输送有关：明尼苏达州红湖泥炭地的小型含水层测试
DOI：
10.1016/j.jhydrol.2020.125686
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发表时间：
2020
影响因子：
6.4
通讯作者：
A. Reeve
中科院分区：
文献类型：
--
作者：
P. Glaser;Joshua L. Rhoades;A. Reeve
在地下水模型中，水力传导性(K)是一个关键但有问题的参数，特别是在模拟脆弱易变形介质（如泥炭沉积物）中的流动时。因此，K代表了将水文过程与泥炭地碳平衡相结合的模型的关键误差来源，泥炭地是全球重要的温室气体来源。因此，我们在明尼苏达州北部1300平方公里的红湖泥炭地的两个中尺度沼泽地形上进行了小型含水层试验。这些测试提供了在大（bbb900 m3）模型域中确定K的精细尺度分布的双重优势。此外，24小时的泵送作业所产生的应力应该能够调动整个深层泥炭矿床的生物气体池。通过24 ~ 38口井监测抽水结果，借助PEST（参数估计分析）校准三维有限体积地下水模型。在沼泽森林（10−5 ~ 10−6m s−1）和沼泽草坪（10−3 ~ 10−4m s−1）地点，在其深层（10 ~ 40 m）泥炭剖面中测定了高K值。与水平层理面相反，这些试验还发现了垂直连续的高或低K值带，分解程度随深度增加。垂向K带暗示了三种不同的气泡输送模式，这些模式或局部扩张或部分阻塞泥炭孔隙。此外，这些测试还为将K与北美北部大陆中部所有大型（bbb20 km2）森林沼泽复合体的发展联系起来的概念模型提供了新的见解。
Hydraulic conductivity (K) is a key but problematic parameter in groundwater models particularly those that simulate flow in weak, readily deformable media, such as peat deposits. As a result, K represents a critical source of error in models that couple hydrological processes with the carbon balance of peatlands, a globally important source for greenhouse gases. We therefore conducted mini-aquifer tests on two mesoscale bog landforms within the large 1300 km2Red Lake Peatland of northern Minnesota. These tests offer the dual advantage of determining the fine-scale distribution of K within a large (>900 m3) model domain. In addition, the stress created by a 24 h pumping operation should be capable of mobilizing pools of biogenic gases thoughout a deep peat deposit. The pumping results were monitored by 24 to 38 wells in order to calibrate a 3D finite-volume groundwater model with the aid of PEST (Parameter Estimation Analysis). High K values were determined at a Bog Forest (10−5to 10−6m s−1) and Bog Lawn (10−3to 10−4m s−1) sites, throughout their deep (>4 m) peat profiles. These tests also detected vertically continuous zones of unexpectedly high or low K values in contrast to the horizontal bedding planes and increasing degree of decomposition with depth. The vertical K zones are suggestive of three different modes of bubble transport that either locally dilate or partially block the peat pores. In addition, the tests provided new insights on a conceptual model linking K to the development of all large (>20 km2) forested bog complexes in mid-continental boreal North America.