C-14 Variation of Dissolved Lignin in Arctic River Systems

Assessing permafrost-release signals in arctic rivers is challenging due to mixing of complex carbon components of contrasting ages. Compound-specific C-14 analysis of terrestrially derived molecules may reduce the influence of mixed carbon sources and potentially provide a closer examination on the...

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Bibliographic Details
Published in:Journal of Plant Ecology
Main Authors: Feng, Xiaojuan, Vonk, Jorien E., Griffin, Claire, Zimov, Nikita, Montlucon, Daniel B., Wacker, Lukas, Eglinton, Timothy I.
Format: Article in Journal/Newspaper
Language:English
Published: AMER CHEMICAL SOC 2017
Subjects:
Compound-specific radiocarbon analysis
arctic rivers
dissolved organic matter
lignin phenols
Keeling plot
Plant Sciences
Environmental Sciences & Ecology
Forestry
TERRESTRIAL CARBON TRANSFER
ANCIENT PERMAFROST CARBON
ORGANIC-MATTER
MULTIMOLECULAR TRACERS
RADIOCARBON ANALYSIS
AMAZON RIVER
EXPORT
BIOMARKERS
DELTA-C-14
COMPONENTS
Arctic
Kolyma
permafrost
Online Access:http://ir.ibcas.ac.cn/handle/2S10CLM1/22127
https://doi.org/10.1093/jpe/rtw114
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Summary:Assessing permafrost-release signals in arctic rivers is challenging due to mixing of complex carbon components of contrasting ages. Compound-specific C-14 analysis of terrestrially derived molecules may reduce the influence of mixed carbon sources and potentially provide a closer examination on the dynamics of permafrost-derived carbon in arctic rivers. Here we employed a recently modified method to determine radiocarbon contents of lignin phenols, as a classic tracer for terrestrial carbon, isolated from the dissolved organic matter (DOM) of two arctic river systems that showed contrasting seasonal dynamics and age components in DOM. While dissolved lignin had relatively invariant C-14 contents in the Mackenzie, it was more concentrated and C-14 enriched during spring thaw but relatively diluted and C-14-depleted in the summer flow or permafrost thaw waters in the Kolyma. Remarkably, the covariance between dissolved lignin concentrations and its C-14 contents nicely followed the Keeling plot, indicating mixing of a young pool of dissolved lignin with an aged pool of a constant concentration within the river. Using model parameters, we showed that although the young pool had similarly modern ages in both rivers, Kolyma had a much higher concentration of aged dissolved lignin and/or with older ages. With this approach, our study not only provided the first set of C data on dissolved lignin phenols in rivers but also demonstrated that the age and abundance of the old DOM pool can be assessed by radiocarbon dating of dissolved lignin in arctic rivers related to permafrost release.

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