Evidence for glacial geological controls on the hydrology of Maine (USA) peatlands
Evidence for glacial geological controls on the hydrology of Maine (USA) peatlands
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DOI：
10.1130/g46844.1
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发表时间：
2020-08-01
期刊：
影响因子：
5.8
通讯作者：
Slater, Lee
中科院分区：
文献类型：
--
作者：
Chen, Xi;Comas, Xavier;Slater, Lee
淡水池通常在泥炭地中形成偏心新月形图案，泥炭地是重要的大气甲烷（CH4）来源，并且在一些消融区域显示出与埃斯克的明显空间关联。然而，很少考虑泥炭地的底层可渗透冰川沉积物（例如埃斯克）在调节水文地质甚至碳循环方面的作用。在这项研究中，探地雷达成像和直接取芯证实，在美国缅因州驯鹿沼泽和卡诺科卢斯沼泽中，簇状水池与与泥炭土接触的埋藏埃斯克波峰一致。水头和地球化学数据与激光雷达相结合表明水从浅层泥炭垂直流向可渗透的esker波峰，这表明不稳定有机碳的向下输送增强，这可能加速了深层泥炭中的产甲烷速率。因此，Eskers 可能可以作为深层泥炭中 CH4 产量增加的代表，这得到了溶解 CH4 分布差异的支持，具体取决于与池的接近程度。从多个来源收集的地理数据表明，许多带有偏心水池的泥炭地似乎位于缅因州和芬诺斯坎迪亚的埃斯克系统附近。这些地质因素可能很重要，但以前未被认识到对泥炭地水和碳循环的控制作用。
Freshwater pools commonly form eccentric crescent patterns in peatlands, an important atmospheric methane (CH4) source, and show an apparent spatial association with eskers in some deglaciated regions. However, the role of underlying permeable glacial deposits such as eskers in regulating hydrogeology, and perhaps even carbon cycling, in peatlands is rarely considered. In this study, ground-penetrating radar imaging and direct coring confirmed that clustered pools coincide with buried esker crests in contact with peat soil in Caribou Bog and Kanokolus Bog in Maine (USA). Hydraulic head and geochemical data combined with lidar indicate vertical water flow from shallow peat toward the permeable esker crests, suggesting enhanced downward transport of labile organic carbon that presumably accelerates rates of methanogenesis in deep peat. Eskers might therefore serve as proxies for enhanced CH4 production in deep peat, as supported by differences in dissolved CH4 profiles depending on proximity to pools. Geographic data compiled from multiple sources suggest that many peatlands with eccentric pools appear to be located proximal to esker systems in Maine and Fennoscandia. These geological factors may be important, previously unrecognized controls on water and the carbon cycle in peatlands.