New progress achieved in seasonal dynamics of dissolved organic carbon of permafrost peatland through Chinese-United States EcoPartnership relationships

摘要

Permafrost peatland plays an important role in the global carbon (C) cycle, and dissolved organic carbon (DOC) is one of the most important components to C budgets in this system. Through the Chinese-United States EcoPartnership program, Dr Xianwei Wang, Li Sun, and Prof Changchun Song et al. from the Northeast Institute of Geography and Agroecology of Chinese Academy of Sciences and Prof Aixin Hou from the Louisiana State University observed dynamics of DOC concentrations and specific ultraviolet absorbance at 254 nm (SUVA_(254)) obtained from soil porewater of permafrost peatlands for two growing seasons in the Great Hing'an Mountains, Northeast China. Soil porewater DOC concentrations varied greatly with depths during the growing season, ranging between 22.08 and 65.02 mg L~(-1). There was no significant relationship between DOC concentrations and SUVA_(254). DOC concentrations were higher in autumn and increased as the seasonal thaw depth increased. DOC concentrations of supra-permafrost water at freeze-thaw boundary were also higher than those at the other soil depths. Temperature and thawing depth had been shown to affect DOC concentrations at different soil depths. Our finding suggests that warming and deepening of the active layer likely increase the DOC productions in the permafrost peatland, which may influence the C balance in these C-enriched ecosystems.