"Subsurface methane dynamics of fens: Biogeochemical controls on production, peat free-phase gas content and efflux"

“沼泽地下甲烷动态：对生产、泥炭游离相气体含量和流出的生物地球化学控制”

• 批准号: 342020-2012
• 负责人: Strack, Maria
• 金额: $ 2.33万
• 依托单位: University of Waterloo
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=595550
• 关键词: Subsurface; methane; dynamics; fens; Biogeochemical

Peatlands are important ecosystems in Canada, covering approximately 12% of the country's landmass. These ecosystems play an important role in the global carbon cycle, accounting for up to one third of global soil carbon stock and up to 10% of atmospheric emissions of the greenhouse gas methane (CH4). Despite this important role, spatial and temporal patterns of CH4 fluxes from peatlands are still fairly poorly described, likely because of the contribution of ebullition (release of bubbles) to total CH4 flux. If ebullition is important, this also suggests that bubbles (free-phase gas; FPG) are present within peat soil. Research over the past decade has indicated the presence and importance of FPG in Sphagnum-dominated peatlands; however, very little is known about FPG in more mineral rich peatlands and the relative importance of ebullition to total CH4 flux from these ecosystems. These mineral rich peatlands, fens, have a different vegetation community, and hence soil structure, suggesting that the rate of CH4 production, transport and trapping of FPG may be very different than Sphagnum-dominated peatlands. The proposed research program aims to address this gap in knowledge by 1) determining the stock of CH4 dissolved, and as FPG in several fen peatlands, 2) describing the spatial and temporal variation in the size of this stock, 3) evaluating the importance of ebullition to the total CH4 flux from these fens, and 4) evaluating potential controls on CH4 stock and ebullition.

泥炭地是加拿大重要的生态系统，约占该国陆地面积的12%。这些生态系统在全球碳循环中发挥着重要作用，占全球土壤碳储量的三分之一，占温室气体甲烷(CH4)大气排放量的10%。尽管有这一重要作用，但泥炭地甲烷通量的空间和时间模式仍然描述得相当差，可能是因为沸腾(释放气泡)对总甲烷通量的贡献。如果沸腾作用很重要，这也表明泥炭土壤中存在气泡(游离相气体；FPG)。过去十年的研究表明，浮游植物在泥炭沼泽中的存在和重要性；然而，人们对泥炭中浮游植物在矿物质丰富的泥炭地中的存在以及沸腾对这些生态系统中CH4总通量的相对重要性知之甚少。这些富含矿物质的泥炭地具有不同的植被群落，因此具有不同的土壤结构，这表明甲烷的产生、运输和捕获的速率可能与以泥炭藓为主的泥炭地截然不同。拟议的研究计划旨在通过以下方式解决这一知识缺口：1)确定溶解的甲烷存量，并在几个沼泽泥炭地中作为FPG；2)描述这些存量的空间和时间变化；3)评估沸腾对来自这些沼泽的总甲烷通量的重要性；以及4)评估对甲烷存量和沸腾的潜在控制。