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研究报告

朱晓艳,宋长春,郭跃东,石福习,张加双,乔田华.三江平原泥炭沼泽孔隙水甲烷浓度变化动态及其影响因子[J].环境科学学报,2015,35(7):2233-2239

The porewater methane concentration and controlling factors from the peatlands in the Sanjiang Plain

摘要：湿地土壤孔隙水甲烷浓度变化动态对于揭示湿地碳循环过程具有重要作用.于2012年和2013年对三江平原毛苔草泥炭沼泽不同土壤深度孔隙水甲烷浓度的季节变化动态进行监测,并分析了其关键影响因子.结果表明:植物生长季孔隙水甲烷浓度呈单峰变化趋势,不同土层甲烷浓度峰值(80.45~490.95 μmol·L^-1)主要集中在湿润的生长季末,但年际间存在显著差异;从土壤剖面来看,土壤融通之后,孔隙水中甲烷浓度随着土壤深度的增加而增加;土壤表层(5 cm和10 cm)甲烷浓度主要受到株高(R²=0.6, p=0.005)和土壤充水孔隙率(R²=0.36, p =0.01)的影响,而深层(20~40 cm)甲烷浓度主要受到土壤温度等因素的综合影响.研究还表明,表层土壤孔隙水甲烷浓度能够解释生长季甲烷排放通量变化的26%~60%, 而且短期的极端降雨事件可能不会对甲烷浓度以及甲烷排放产生即时影响,而是出现大约一周的延迟(time lag)现象,这主要取决于实际土壤湿度.

Abstract：The patterns of porewater methane concentration exert great influence on the carbon cycling in wetlands. The temporal patterns and key factors influencing porewater methane concentration of the vertical profile during two growing seasons in 2012 and 2013 were monitored in the Carex lasiocarpa peatland of the Sanjiang Plain. In both years, a unique peak period could be identified with the temporal variation, with peak values ranging from 80.45 to 490.95 μmol·L^-1 at 10 to 40 cm depth, occurring at the end of wet growing seasons. However, there existed significant difference in porewater methane concentration between 2012 and 2013. The porewater CH₄ concentration increased with the soil depth when the soil thoroughly thawed. The CH₄ concentration in the top layer, at the 5 and 10 cm depth, showed a significant lineal relationship to the plant height (R²=0.6, p=0.005) and water-filled porosity of soil (R²=0.36, p=0.01). The soil temperature was the main factor influencing CH₄ concentration at the depth of 20, 30 and 40 cm. The CH₄concentrations in surface layers controlled 26%~60% of the seasonal variation in methane emissions during the study period. Meanwhile, rapid and short-lived precipitation events might have no immediate influence on CH₄ concentration, and lagged for about one week, which primarily depended on the actual soil moisture.