Hydrological processes and permafrost regulate magnitude, source and chemical characteristics of dissolved organic carbon export in a peatland catchment of northeastern China
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 desp...
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Veröffentlicht in: | Hydrology and earth system sciences 2018-02, Vol.22 (2), p.1081-1093 |
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Zusammenfassung: | 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. |
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ISSN: | 1607-7938 1027-5606 1607-7938 |
DOI: | 10.5194/hess-22-1081-2018 |