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Thaw Depth Determines Dissolved Organic Carbon Concentration and Biodegradability on the Northern Qinghai‐Tibetan Plateau
Author(s) -
Mu C. C.,
Abbott B. W.,
Wu X. D.,
Zhao Q.,
Wang H. J.,
Su H.,
Wang S. F.,
Gao T. G.,
Guo H.,
Peng X. Q.,
Zhang T. J.
Publication year - 2017
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2017gl075067
Subject(s) - permafrost , thermokarst , dissolved organic carbon , plateau (mathematics) , total organic carbon , environmental science , biodegradation , carbon fibers , soil carbon , hydrology (agriculture) , environmental chemistry , soil water , carbon cycle , degradation (telecommunications) , soil science , geology , ecosystem , ecology , oceanography , chemistry , geotechnical engineering , materials science , mathematics , mathematical analysis , composite number , computer science , composite material , biology , telecommunications
The response of dissolved organic carbon (DOC) flux to permafrost degradation is one of the major sources of uncertainty in predicting the permafrost carbon feedback. We investigated DOC export and properties over two complete flow seasons in a catchment on the northern Qinghai‐Tibetan Plateau. DOC concentration and biodegradability decreased systematically as thaw depth increased through the season, attributable to changing carbon sources and degree of microbial processing. Increasing DOC aromaticity and δ 13 C‐DOC indicated shifts toward more recalcitrant carbon sources and greater residence time in soils prior to reaching the stream network. These strong and consistent seasonal trends suggest that gradual active layer deepening may decrease DOC export and biodegradability from permafrost catchments. Because these patterns are opposite observations from areas experiencing abrupt permafrost collapse (thermokarst), the overall impact of permafrost degradation on DOC flux and biodegradability may depend on the proportion of the landscape experiencing gradual thaw versus thermokarst.