Institute of Arctic and Alpine Research (INSTAAR), University of Colorado, 1560 30th Street, Boulder, Colorado 80309, USA.
Environ Sci Technol. 2010 Jan 1;44(1):80-6. doi: 10.1021/es901669z.
Methane emissions and element mobility in wetlands are controlled by soil moisture and redox conditions. We manipulated soil moisture by weekly drying and irrigation of mesocosms of peat from a bog and iron and sulfur rich fen. Water table changed more strongly in the decomposed fen peat ( approximately 11 cm) than in the fibric bog peat ( approximately 5 cm), where impacts on redox processes were larger due to larger change in air filled porosity. Methanogenesis was partly decoupled from acetogenesis and acetate accumulated up to 5.6 mmol L(-1) in the fen peat after sulfate was depleted. Irrigation and drying led to rapid redox-cycles with sulfate, hydrogen sulfide, nitrate, and methane being produced and consumed on the scale of days, contributing substantially to the total electron flow and suggesting short-term resilience of the microbial community to intermittent aeration. Anaerobic CO2 production was partly balanced by methanogenesis (0-34%), acetate fermentation (0-86%), and sulfate reduction (1-30%) in the bog peat. In the fen peat unknown electron acceptors and aerenchymatic oxygen influx apparently drove respiration. The results suggest that regular rainfall and subsequent drying may lead to local oxidation-reduction cycles that substantially influence electron flow in electron acceptor poor wetlands.
湿地中的甲烷排放和元素迁移受土壤湿度和氧化还原条件控制。我们通过每周对沼泽泥炭和富含铁和硫的泥沼的中观模型进行干燥和灌溉来控制土壤湿度。分解泥沼泥炭中的地下水位变化（约 11 厘米）比纤维沼泽泥炭中的变化更大（约 5 厘米），由于空气填充孔隙度的变化更大，因此对氧化还原过程的影响更大。产甲烷作用与乙酰化作用部分解耦，并且在硫酸盐耗尽后，泥沼泥炭中乙酸盐积累到 5.6mmol/L。灌溉和干燥导致硫酸盐、硫化氢、硝酸盐和甲烷的快速氧化还原循环，在数天的时间内产生和消耗，对总电子流有很大贡献，并表明微生物群落对间歇曝气具有短期弹性。在沼泽泥炭中，厌氧 CO2 生成部分通过产甲烷作用（0-34%）、乙酸盐发酵（0-86%）和硫酸盐还原（1-30%）得到平衡。在泥沼泥炭中，未知的电子受体和通气组织的氧气流入显然驱动了呼吸作用。结果表明，定期降雨和随后的干燥可能导致局部氧化还原循环，这些循环会极大地影响电子受体贫瘠湿地中的电子流。
