Abstract. Permafrost thawing in peatland has the potential to alter the catchment export of dissolved organic carbon (DOC), thus influencing carbon cycling in linked aquatic and ocean ecosystems. However, peatland along the southern margins of Eurasian permafrost are seldom examined in spite of the presence of considerable risks associated with degradation due to climate warming. This study examines dynamics of DOC export from a permafrost peatland catchment located in northeastern China during the growing seasons of 2012 to 2014. Our findings show that runoff processes affect observed DOC concentrations, magnitudes, sources, and chemical characteristics of stream discharge. The entire catchment exhibits strong potential for annual DOC exporting (4.87 g C m−2), and DOC from the peatland landscape alone is estimated to amount to 12.89 g C m−2. Annual DOC export processes are closely related to total discharge levels, and floods contribute to approximately 85 % of DOC export levels. Flood volumes derived mainly from peat pore water stored in the upper organic layer of the soil profile prior to rainfall events, creating a strong linkage between discharge and DOC concentrations. DOC source and chemical characteristics, as indicated by three fluorescence indexes, have changed regularly according to source shifts occurring as a result of flood and baseflow processes. A deepening of the active layer due to climate warming should elevate proportions of microbial-originated DOC in the baseflow. Given expected future increases in precipitation, our results show that the magnitude of DOC exports from the study region will increase.
Recent changes in nitrate and dissolved organic carbon export from the upper Kuparuk River, North Slope, Alaska
