14C Variation of Dissolved Lignin in Arctic River Systems

Xiaojuan Feng, Jorien E. Vonk, Claire Griffin, Nikita Zimov, Daniel B. Montluçon, Lukas Wacker, Timothy I. Eglinton

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

Assessing permafrost-release signals in arctic rivers is challenging due to mixing of complex carbon components of contrasting ages. Compound-specific 14C 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 14C contents in the Mackenzie, it was more concentrated and 14C-enriched during spring thaw but relatively diluted and 14C-depleted in the summer flow or permafrost thaw waters in the Kolyma. Remarkably, the covariance between dissolved lignin concentrations and its 14C 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 14C 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.

Original languageEnglish (US)
Pages (from-to)334-344
Number of pages11
JournalACS Earth and Space Chemistry
Volume1
Issue number6
DOIs
StatePublished - Aug 17 2017

Bibliographical note

Funding Information:
All molecular 14C data are available in Supporting Information, Table S1. Members of LIP (ETH) are acknowledged for support with the radiocarbon measurements. X.F. acknowledges support from the National Natural Science Foundation of China (41422304, 31370491). T.I.E. acknowledges support from the Swiss National Science foundation (SNF) (#200021_140850) and Grants OCE-9907129, OCE-0137005, and OCE-0526268 from the U.S. National Science Foundation (NSF), and ETH Zürich. J.E.V. thanks support from NWO Rubicon (#825.10.022) and Veni (#863.12.004). X.F. thanks ETH Zürich for postdoctoral support. Support for the Arctic Great Rivers Observatory comes from NSF #ARC-0732821 and #ARC-1107774. The “Young Thousand Talent” recruiting plan of China is acknowledged for start-up support to X.F.

Funding Information:
X.F. acknowledges support from the National Natural Science Foundation of China (41422304, 31370491). T.I.E. acknowledges support from the Swiss National Science foundation (SNF) (#200021-140850) and Grants OCE-9907129, OCE-0137005, and OCE-0526268 from the U.S. National Science Foundation (NSF), and ETH ZuÌrich. J.E.V. thanks support from NWO Rubicon (#825.10.022) and Veni (#863.12.004). X.F. thanks ETH ZuÌrich for postdoctoral support. Support for the Arctic Great Rivers Observatory comes from NSF #ARC-0732821 and #ARC-1107774.

Publisher Copyright:
© 2017 American Chemical Society.

Keywords

  • Compound-specific radiocarbon analysis
  • Keeling plot
  • arctic rivers
  • dissolved organic matter
  • lignin phenols

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