Dissolved organic carbon in permafrost regions: A review

Qiang Ma, Huijun Jin*, Congrong Yu, Victor F. Bense

*Corresponding author for this work

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Abstract

A large quantity of organic carbon (C) is stored in northern and elevational permafrost regions. A portion of this large terrestrial organic C pool will be transferred by water into soil solution (~0.4 Pg C yr−1) (1 Pg=1015 g), rivers (~0.06 Pg C yr−1), wetlands, lakes, and oceans. The lateral transport of dissolved organic carbon (DOC) is the primary pathway, impacting river biogeochemistry and ecosystems. However, climate warming will substantially alter the lateral C shifts in permafrost regions. Vegetation, permafrost, precipitation, soil humidity and temperature, and microbial activities, among many other environmental factors, will shift substantially under a warming climate. It remains uncertain as to what extent the lateral C cycle is responding, and will respond, to climate change. This paper reviews recent studies on terrestrial origins of DOC, biodegradability, transfer pathways, and modelling, and on how to forecast of DOC fluxes in permafrost regions under a warming climate, as well as the potential anthropogenic impacts on DOC in permafrost regions. It is concluded that: (1) surface organic layer, permafrost soils, and vegetation leachates are the main DOC sources, with about 4.72 Pg C DOC stored in the topsoil at depths of 0–1 m in permafrost regions; (2) in-stream DOC concentrations vary spatially and temporally to a relatively small extent (1–60 mg C L−1) and annual export varies from 0.1–10 g C m–2 yr–1; (3) biodegradability of DOC from the thawing permafrost can be as high as 71%, with a median at 52%; (4) DOC flux is controlled by multiple factors, mainly including vegetation, soil properties, permafrost occurrence, river discharge and other related environmental factors, and (5) many statistical and process-based models have been developed, but model predictions are inconsistent with observational results largely dependent on the individual watershed characteristics and future discharge trends. Thus, it is still difficult to predict how future lateral C flux will respond to climate change, but changes in the DOC regimes in individual catchments can be predicted with a reasonable reliability. It is advised that sampling protocols and preservation and analysis methods should be standardized, and analytical techniques at molecular scales and numerical modeling on thermokarsting processes should be prioritized.

Original languageEnglish
Pages (from-to)349–364
JournalScience China Earth Sciences
Volume62
Issue number2
Early online date1 Jan 2019
DOIs
Publication statusPublished - Feb 2019

Keywords

  • Aquatic ecosystem
  • Carbon biodegradability
  • Dissolved organic carbon (DOC)
  • DOC export
  • Permafrost degradation

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  • Research Output

    • 1 Citations
    • 1 Comment/Letter to the editor

    Erratum to: dissolved organic carbon in permafrost regions: a review

    Ma, Q., Jin, H., Yu, C. & Bense, V. F., Apr 2019, In : Science China Earth Sciences. 62, 4, p. 750-750 1 p.

    Research output: Contribution to journalComment/Letter to the editorAcademic

    Open Access
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