Stable Carbon composition of Methane in Eurasian Peatlands: CH4 production, transport and oxidation

欧亚泥炭地是大气中温室气体CH4的重要来源。然而，尚不清楚北方泥炭地内CH4通量的强度是否会随着气候变化而改变。在这里，我们建议通过研究泥炭剖面内产生和氧化区消耗之间的CH4平衡机制以及CH4运输机制来缩小这一知识差距。调查将沿着从芬兰到俄罗斯西北部最大的泥炭地地区之一的海洋大陆横断面进行。在每个站点，我们将测量(i)孔隙水中CH4浓度和排放的CH4外排，（ii）作为甲烷生成底物的乙酸酯浓度；（iii）孔隙水和排放CH4的稳定碳同位素组成，以评估甲烷生成的来源、CH4氧化势和CH4从泥炭深度向大气输送的可能机制。获得的数据将提高对空间（从微观尺度——泥炭地的微观形态：小丘、草坪、洼地——到宏观尺度沿着海洋-大陆样带）和时间（春夏季节）两个维度上CH4转换机制的认识。了解北方泥炭地甲烷交换的具体机制将有助于开发新的碳平衡模式，并对现有的全球和区域碳平衡模式进行调整。

Eurasian peatlands are important sources of the greenhouse gas CH4 to the atmosphere. However, it is not clear whether the intensity of CH4 flux within boreal peatlands would alter in a changing climate. Here, we propose to narrow this knowledge gap by investigating mechanisms of the CH4 balance between production within peat profile and consumption in peat oxidative zones as well as CH4 transport mechanisms. The investigation will be conducted along a maritimecontinental transect spanning from Finland to one of largest peatlands areas in North-Western Russia. At each site, we will measure (i) porewater CH4 concentrations and emitted CH4 efflux, (ii) concentrations of acetates as substrates for methanogenesis; (iii) stable C isotopic composition of porewater- and emitted CH4 to assess the sources of methanogenesis, CH4-oxidative potential and possible mechanisms of CH4 transport from peat depth to the atmosphere. Obtained data will improve the knowledge about mechanisms of the CH4 turnover on both spatial (from micro-scale - peatland’s microforms: hummocks, lawns, hollows - to macro-scale along a maritime-continental transect) and temporal (over spring-summer seasons) dimensions. Knowledge of the specific mechanisms of CH4 turnover within boreal peatlands will help in the development of the new- and adjustment of the existing global- and regional models of C balance.