Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Volume 12, issue 15
Biogeosciences, 12, 4841–4860, 2015
https://doi.org/10.5194/bg-12-4841-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Biogeosciences, 12, 4841–4860, 2015
https://doi.org/10.5194/bg-12-4841-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 14 Aug 2015

Research article | 14 Aug 2015

Multi-molecular tracers of terrestrial carbon transfer across the pan-Arctic: comparison of hydrolyzable components with plant wax lipids and lignin phenols

X. Feng1,2,3, Ö. Gustafsson4, R. M. Holmes5, J. E. Vonk6,7, B. E. van Dongen8, I. P. Semiletov9,10,11, O. V. Dudarev10,11, M. B. Yunker12, R. W. Macdonald13, D. B. Montluçon2,3, and T. I. Eglinton2,3 X. Feng et al.
  • 1State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
  • 2Geological Institute, ETH Zurich, Zurich, Switzerland
  • 3Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution (WHOI), Woods Hole, MA, USA
  • 4Department of Environmental Science and Analytical Chemistry (ACES) and the Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
  • 5Woods Hole Research Center (WHOI), Falmouth, MA, USA
  • 6Department of Earth Sciences, Utrecht University, Utrecht, the Netherlands
  • 7Arctic Centre, University of Groningen, Groningen, the Netherlands
  • 8School of Earth, Atmospheric and Environmental Sciences (SEAES) and the Williamson Research Centre for Molecular Environmental Science, University of Manchester, Manchester, UK
  • 9International Arctic Research Center (IARC), University of Alaska Fairbanks, Fairbanks, AK, USA
  • 10Pacific Oceanological Institute, Far Eastern Branch Russian Academy of Sciences (FEBRAS), Vladivostok, Russia
  • 11National Research Tomsk Polytechnic University, Tomsk, Russia
  • 127137 Wallace Dr., Brentwood Bay, BC, Canada
  • 13Department of Fisheries and Oceans, Institute of Ocean Sciences, Sidney, BC, Canada

Abstract. Hydrolyzable organic carbon (OC) comprises a significant component of sedimentary particulate matter transferred from land into oceans via rivers. Its abundance and nature are however not well studied in Arctic river systems, and yet may represent an important pool of carbon whose fate remains unclear in the context of mobilization and related processes associated with a changing climate. Here, we examine the molecular composition and source of hydrolyzable compounds isolated from sedimentary particles derived from nine rivers across the pan-Arctic. Bound fatty acids (b-FAs), hydroxy FAs, n-alkane-α,ω-dioic acids (DAs) and phenols were the major components released upon hydrolysis of these sediments. Among them, b-FAs received considerable inputs from bacterial and/or algal sources, whereas ω-hydroxy FAs, mid-chain substituted acids, DAs, and hydrolyzable phenols were mainly derived from cutin and suberin of higher plants. We further compared the distribution and fate of suberin- and cutin-derived compounds with those of other terrestrial biomarkers (plant wax lipids and lignin phenols) from the same Arctic river sedimentary particles and conducted a benchmark assessment of several biomarker-based indicators of OC source and extent of degradation. While suberin-specific biomarkers were positively correlated with plant-derived high-molecular-weight (HMW) FAs, lignin phenols were correlated with cutin-derived compounds. These correlations suggest that, similar to leaf-derived cutin, lignin was mainly derived from litter and surface soil horizons, whereas suberin and HMW FAs incorporated significant inputs from belowground sources (roots and deeper soil). This conclusion is supported by the negative correlation between lignin phenols and the ratio of suberin-to-cutin biomarkers. Furthermore, the molecular composition of investigated biomarkers differed between Eurasian and North American Arctic rivers: while lignin dominated in the terrestrial OC of Eurasian river sediments, hydrolyzable OC represented a much larger fraction in the sedimentary particles from Colville River. Hence, studies exclusively focusing on either plant wax lipids or lignin phenols will not be able to fully unravel the mobilization and fate of bound OC in Arctic rivers. More comprehensive, multi-molecular investigations are needed to better constrain the land–ocean transfer of carbon in the changing Arctic, including further research on the degradation and transfer of both free and bound components in Arctic river sediments.

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Currently very few studies have examined the distribution and fate of hydrolyzable organic carbon (OC) in Arctic sediments, whose fate remains unclear in the context of climate change. Our study focuses on the source, distribution and fate of hydrolyzable OC as compared with plant wax lipids and lignin phenols in the sedimentary particles of nine Arctic and sub-Arctic rivers. This multi-molecular approach allows for a comprehensive investigation of terrestrial OC transfer via Arctic rivers.
Currently very few studies have examined the distribution and fate of hydrolyzable organic...
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