Hydrological processes and permafrost regulate magnitude, source and chemical characteristics of dissolved organic carbon export in a peatland catchment of northeastern China

Abstract

Abstract. Permafrost thawing in peatlands has the potential to alter the catchment export of dissolved organic carbon (DOC), thus influencing the carbon balance and cycling in linked aquatic and ocean ecosystems. Peatlands along the southern margins of the Eurasian permafrost are relatively underexplored despite the considerable risks associated with permafrost degradation due to climate warming. This study examined dynamics of DOC export from a permafrost peatland catchment located in northeastern China during the 2012 to 2014 growing seasons. The estimated annual DOC loads varied greatly between 3211 and 19 022 kg yr −1 , with a mean DOC yield of 4.7 g m −2 yr −1 . Although the estimated DOC yield was in the lower range compared with other permafrost regions, it was still significant for the net carbon balance in the studied catchment. There were strong linkages between daily discharge and DOC concentrations in both wet and dry years, suggesting a transport-limited process of DOC delivery from the catchment. Discharge explained the majority of both seasonal and interannual variations of DOC concentrations, which made annual discharge a good indicator of total DOC load from the catchment. As indicated by three fluorescence indices, DOC source and chemical characteristics tracked the shift of flow paths during runoff processes closely. Interactions between the flow path and DOC chemical characteristics were greatly influenced by the seasonal thawing of the soil active layer. The deepening of the active layer due to climate warming likely increases the proportion of microbial-originated DOC in baseflow discharge.

Dissolved organic carbon in permafrost regions: A review

“…Quantification of DOC dynamics can be achieved by process-based modelling or regression analysis. Regression analysis employs the correlation of DOC flux and environmental factors, such as discharge, width of water body, water pH, proportion of upland/wetland area in a watershed, and soil C/N ratio (Aitkenhead and McDowell, 2000;Jutras et al, 2011;Guo et al, 2018;Rodríguez-Jeangros, 2018). Then, fluvial DOC flux can be predicted by regression models.…”

Distributive Features of Dissolved Organic Carbon in Aquatic Systems in the Source Area of the Yellow River on the Northeastern Qinghai–Tibet Plateau, China

“…In 2017, DOC concentrations were the greatest in summer-autumn (7.0 ± 4.8 mg C•L −1 ), followed by those in the snow-melt season (3.6 ± 6.0 mg C•L −1 ) and winter season (1.1 ± 0.5 mg C•L −1 ) (Figure 2D). In northern permafrost regions, such as the upper Yukon River Basin, seasonal DOC concentrations are characterized by the greatest average in-stream DOC (36.12 mg C•L −1 ) in the snow-melt season and decreased to that in summer-autumn (7.3 mg C•L −1 ) Guo et al, 2018). It is generally proven that in-stream DOC concentrations are positively related with discharge.…”

The Forgotten Nutrient—The Role of Nitrogen in Permafrost Soils of Northern China

“…1b). The annual mean temperature and precipitation in this catchment are −4.2°C and 425 mm, respectively [1959[ (Guo et al, 2018]. Bogs are distributed along the river valley and surrounded by birch (Betula platyphylla Suk.)…”