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Erosion of organic carbon in the Arctic as a geological carbon dioxide sink

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Abstract

Soils of the northern high latitudes store carbon over millennial timescales (thousands of years) and contain approximately double the carbon stock of the atmosphere1,2,3. Warming and associated permafrost thaw can expose soil organic carbon and result in mineralization and carbon dioxide (CO2) release4,5,6. However, some of this soil organic carbon may be eroded and transferred to rivers7,8,9. If it escapes degradation during river transport and is buried in marine sediments, then it can contribute to a longer-term (more than ten thousand years), geological CO2 sink8,9,10. Despite this recognition, the erosional flux and fate of particulate organic carbon (POC) in large rivers at high latitudes remains poorly constrained. Here, we quantify the source of POC in the Mackenzie River, the main sediment supplier to the Arctic Ocean11,12, and assess its flux and fate. We combine measurements of radiocarbon, stable carbon isotopes and element ratios to correct for rock-derived POC10,13,14. Our samples reveal that the eroded biospheric POC has resided in the basin for millennia, with a mean radiocarbon age of 5,800 ± 800 years, much older than the POC in large tropical rivers13,14. From the measured biospheric POC content and variability in annual sediment yield15, we calculate a biospheric POC flux of teragrams of carbon per year from the Mackenzie River, which is three times the CO2 drawdown by silicate weathering in this basin16. Offshore, we find evidence for efficient terrestrial organic carbon burial over the Holocene period, suggesting that erosion of organic carbon-rich, high-latitude soils may result in an important geological CO2 sink.

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Figure 1: Source of POC in the Mackenzie River basin.
Figure 2: Transport of POC in the Mackenzie River.
Figure 3: Fate of particulate organic carbon offshore.

References

  1. Gorham, E. Northern peatlands: Role in the carbon cycle and probable responses to climatic warming. Ecol. Appl. 1, 182–195 (1991)

    Article  PubMed  Google Scholar 

  2. Hugelius, G. et al. Estimated stocks of circumpolar permafrost carbon with quantified uncertainty ranges and identified data gaps. Biogeosciences 11, 6573–6593 (2014)

    Article  ADS  Google Scholar 

  3. Schuur, E. A. G. et al. Vulnerability of permafrost carbon to climate change: Implications for the global carbon cycle. Bioscience 58, 701–714 (2008)

    Article  Google Scholar 

  4. Guo, L., Ping, C.-L. & Macdonald, R. W. Mobilization pathways of organic carbon from permafrost to arctic rivers in a changing climate. Geophys. Res. Lett. 34, L13603 (2007)

    Article  ADS  Google Scholar 

  5. MacDougall, A. H., Avis, C. A. & Weaver, A. L. Significant contribution to climate warming from the permafrost carbon feedback. Nature Geosci. 5, 719–721 (2012)

    Article  ADS  CAS  Google Scholar 

  6. Schädel, C. et al. Circumpolar assessment of permafrost C quality and its vulnerability over time using long-term incubation data. Glob. Change Biol. 20, 641–652 (2014)

    Article  ADS  Google Scholar 

  7. Goñi, M. A., Yunker, M. B., Macdonald, R. W. & Eglinton, T. I. The supply and preservation of ancient and modern components of organic carbon in the Canadian Beaufort Shelf of the Arctic Ocean. Mar. Chem. 93, 53–73 (2005)

    Article  Google Scholar 

  8. Vonk, J. E. et al. Activation of old carbon by erosion of coastal and subsea permafrost in Arctic Siberia. Nature 489, 137–140 (2012)

    Article  ADS  CAS  PubMed  Google Scholar 

  9. Vonk, J. E. & Gustafsson, O. Permafrost-carbon complexities. Nature Geosci. 6, 675–676 (2013)

    Article  ADS  CAS  Google Scholar 

  10. Galy, V. et al. Efficient organic carbon burial in the Bengal fan sustained by the Himalayan erosional system. Nature 450, 407–410 (2007)

    Article  ADS  CAS  PubMed  Google Scholar 

  11. Stein, R. & Macdonald, R. W. The Organic Carbon Cycle in the Arctic Ocean (Springer, 2004)

    Book  Google Scholar 

  12. Macdonald, R. W. et al. A sediment and organic carbon budget for the Canadian Beaufort Shelf. Mar. Geol. 144, 255–273 (1998)

    Article  ADS  CAS  Google Scholar 

  13. Galy, V. & Eglinton, T. I. Protracted storage of biospheric carbon in the Ganges-Brahmaputra basin. Nature Geosci. 4, 843–847 (2011)

    Article  ADS  CAS  Google Scholar 

  14. Bouchez, J. et al. Source, transport and fluxes of Amazon River particulate organic carbon: insights from river sediment depth-profiles. Geochim. Cosmochim. Acta 133, 280–298 (2014)

    Article  ADS  CAS  Google Scholar 

  15. Carson, M. A., Jasper, J. N. & Conly, F. M. Magnitude and sources of sediment input to the Mackenzie Delta, Northwest Territories, 1974–94. Arctic 51, 116–124 (1998)

    Article  Google Scholar 

  16. Gaillardet, J., Dupré, B., Louvat, P. & Allegre, C. A. Global silicate weathering and CO2 consumption rates deduced from the chemistry of large rivers. Chem. Geol. 159, 3–30 (1999)

    Article  ADS  CAS  Google Scholar 

  17. Sundquist, E. T. & Visser, K. in Treatise on Geochemistry (ed. Schlesinger, W. H. ), Vol. 8 Biogeochemistry 425–472 (Elsevier-Pergamon, 2004)

    Google Scholar 

  18. Blair, N. E. & Aller, R. C. The fate of terrestrial organic carbon in the marine environment. Annu. Rev. Mar. Sci. 4, 17.1–17.23 (2012)

    Article  Google Scholar 

  19. Hayes, J. M., Strauss, H. & Kaufman, A. J. The abundance of 13C in marine organic matter and isotopic fractionation in the global biogeochemical cycle of carbon during the past 800 Ma. Chem. Geol. 161, 103–125 (1999)

    Article  ADS  CAS  Google Scholar 

  20. Berner, R. A. Atmospheric CO2 levels over Phanerozoic time. Science 249, 1382–1386 (1990)

    Article  ADS  CAS  PubMed  Google Scholar 

  21. Hilton, R. G., Gaillardet, J., Calmels, D. & Birck, J. L. Geological respiration of a mountain belt revealed by the trace element rhenium. Earth Planet. Sci. Lett. 403, 27–36 (2014)

    Article  ADS  CAS  Google Scholar 

  22. Hilton, R. G. et al. Climatic and geomorphic controls on the erosion of terrestrial biomass from subtropical mountain forest. Glob. Biogeochem. Cycles 26, http://dx.doi.org/10.1029/2012GB004314 (2012)

  23. Galy, V., Peucker-Ehrenbrink, B. & Eglinton, T. Global carbon export from the terrestrial biosphere controlled by erosion. Nature 521, 204–207 (2015)

    Article  ADS  CAS  PubMed  Google Scholar 

  24. Burdige, D. J. Burial of terrestrial organic matter in marine sediments: a re-assessment. Glob. Biogeochem. Cycles 19, GB4011 (2005)

    Article  ADS  Google Scholar 

  25. MacDonald, G. M. et al. Rapid development of the circumarctic peatland complex and atmospheric CH4 and CO2 variations. Science 314, 285–288 (2006)

    Article  ADS  CAS  PubMed  Google Scholar 

  26. Dellinger, M. et al. Lithium isotopes in large rivers reveal the cannibalistic nature of modern continental weathering and erosion. Earth Planet. Sci. Lett. 401, 359–372 (2014)

    Article  ADS  CAS  Google Scholar 

  27. Kuhry, P. & Vitt, D. H. Fossil carbon/nitrogen ratios as a measure of peat decomposition. Ecology 77, 271–275 (1996)

    Article  Google Scholar 

  28. Feng, X. et al. Differential mobilization of terrestrial carbon pools in Eurasian Arctic river basins. Proc. Natl Acad. Sci. USA 110, 14168–14173 (2013)

    Article  ADS  CAS  PubMed  PubMed Central  Google Scholar 

  29. Goñi, M. A. et al. Distribution and sources of organic matter in surface marine sediments across the North American Arctic margin. J. Geophys. Res. 118, 4017–4035 (2013)

    Article  ADS  Google Scholar 

  30. Drenzek, N. J., Montluçon, D. B., Yunker, M. B., Macdonald, R. W. & Eglinton, T. I. Constraints on the origin of sedimentary organic carbon in the Beaufort Sea from coupled molecular 13C and 14C measurements. Mar. Chem. 103, 146–162 (2007)

    Article  CAS  Google Scholar 

  31. Schuur, E. A. G. et al. Climate change and the permafrost carbon feedback. Nature 520, 171–179 (2015)

    Article  ADS  CAS  PubMed  Google Scholar 

  32. Hilton, R. G., Galy, A., Hovius, N., Horng, M. J. & Chen, H. The isotopic composition of particulate organic carbon in mountain rivers of Taiwan. Geochim. Cosmochim. Acta 74, 3164–3181 (2010)

    Article  ADS  CAS  Google Scholar 

  33. Moran, K., Hill, P. R. & Blasco, S. M. Interpretation of piezocone penetrometer profiles in sediment from the Mackenzie Trough, Canadian Beaufort Sea. J. Sedim. Petrol. 59, 88–97 (1989)

    Google Scholar 

  34. Komada, T., Anderson, M. R. & Dorfmeier, C. L. Carbonate removal from coastal sediments for the determination of organic carbon and its isotopic signatures, 13C and 14C: comparison of fumigation and direct acidification by hydrochloric acid. Limnol. Oceanogr. 6, 254–262 (2008)

    Article  CAS  Google Scholar 

  35. Whiteside, J. H. et al. Pangean great lake paleoecology on the cusp of the end-Triassic extinction. Palaeogeogr. Palaeoclimatol. Palaeoecol. 301, 1–17 (2011)

    Article  Google Scholar 

  36. Stuiver, M. & Polach, H. A. Discussion: Reporting of 14C data. Radiocarbon 19, 55–63 (1977)

    Article  Google Scholar 

  37. Stuiver, M. & Reimer, P. J. Extended 14C database and revised CALIB radiocarbon calibration program. Radiocarbon 35, 215–230 (1993)

    Article  Google Scholar 

  38. Reimer, P. J. et al. IntCal09 and Marine09 radiocarbon age calibration curves, 0–50,000 years cal BP. Radiocarbon 51, 1111–1150 (2009)

    Article  CAS  Google Scholar 

  39. Coulthard, R. D., Furze, M. F. A., Pienkowski, A. J., Nixon, F. C. & England, J. H. New marine ΔR values for Arctic Canada. Quat. Geochronol. 5, 419–434 (2010)

    Article  Google Scholar 

  40. Johnston, D. T., Macdonald, F. A., Gill, B. C., Hoffman, P. F. & Schrag, D. P. Uncovering the Neoproterozoic carbon cycle. Nature 483, 320–323 (2012)

    Article  ADS  CAS  PubMed  Google Scholar 

  41. Bird, M., Santruckova, H., Lloyd, J. & Lawson, E. The isotopic composition of soil organic carbon on a north-south transect in western Canada. Eur. J. Soil Sci. 53, 393–403 (2002)

    Article  CAS  Google Scholar 

  42. Brown, J. et al. Circum-Arctic Map of Permafrost and Ground Ice Conditions http://nsidc.org/data/ggd318 (National Snow and Ice Data Center/World Data Center for Glaciology, 1998)

    Google Scholar 

Download references

Acknowledgements

Radiocarbon measurements were funded by the Natural Environment Research Council (NERC), UK (Allocation 1611.0312) to R.G.H and C.B. Fieldwork was funded by CNRS (OXYMORE and CANNIBALT) to J.G. and R.G.H., the Woods Hole Oceanographic Institution Arctic Research Initiative to V.G. and an Early Career Research Grant by the British Society for Geomorphology to R.G.H. V.G. was supported by the US National Science Foundation (OCE-0928582) and H.C. by a Royal Society University Fellowship. The research was carried out under Scientific Research Licence No. 14802 issued by the Aurora Research Centre, who we thank for logistical support (in particular D. Ross and J. Gareis). We also thank I. Peters for preparation of offshore borehole samples, C. Johnson, X. Philippon and M. Bollard for analytical assistance, E. Tipper and K. Hilton for field assistance and discussions and D. Ofukany, G. Lennie, R. Wedel and R. Pilling of Environment Canada for loan of equipment.

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Authors and Affiliations

Authors

Contributions

R.G.H., V.G. and J.G. conceived the study and R.G.H., J.B., D.C., V.G. and M.D. designed the fieldwork and collected the river samples. M.O. and H.C. collected sediment and carbonate data from the offshore borehole. R.G.H., V.G., M.D., C.B. and D.G. processed the samples and carried out the geochemical analyses. R.G.H. wrote the manuscript with input from all co-authors.

Corresponding author

Correspondence to Robert G. Hilton.

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Competing interests

The authors declare no competing financial interests.

Extended data figures and tables

Extended Data Figure 1 The location of river depth profiles collected from the Mackenzie River.

Three locations along the Mackenzie River were sampled (circles) at the delta (black), Tsiigehtchic (grey) and Norman Wells (white) in addition to the major tributaries, the Liard River (red diamond), Arctic Red River (light blue square) and Peel River (dark blue square). The location of the sediment core MTW01 from the Mackenzie trough is shown (triangle). a, Major river channels (black lines) overlain on digital elevation model GMTED 15 arcsec with upstream sediment source catchment areas delineated by flow accumulation and flow direction outputs from the digital elevation model (dotted lines). The Great Slave Lake is indicated upstream of the Liard confluence and acts as an effective sediment trap in the basin15. b, Permafrost zone coverage in the upstream areas of the basin42. White rectangle shows the sample locations near the Mackenzie delta displayed in c, overlain on LANDSAT imagery.

Extended Data Figure 2 Source of particulate organic carbon in the Mackenzie River basin.

a, Radiocarbon content (reported as Fmod) as a function of the stable isotope ratio of organic carbon (δ13Corg) of river sediments for the Mackenzie River (circles) and its major tributaries (diamonds and squares) for suspended load samples from river depth profiles (filled symbols) and river bed materials (open symbols). Dashed lines and shaded regions show hypothetical compositions produced by mixing rock-derived POCpetro40 and POCbiosphere41. b, Fmod as a function of Al/OCtotal. High Al/OCtotal and low Fmod correspond to the petrogenic source of POC (POCpetro). Linear trends are shown for the Peel and Arctic Red rivers (blue, y = (−1.5 ± 0.3 × 10−6)x + (0.85 ± 0.11), r2 = 0.85, P < 0.02), the Mackenzie River at delta (black, y = (−5.9 ± 0.5 × 10−6)x + (0.65 ± 0.03), r2 = 0.95, P < 0.001), and the Mackenzie and Liard rivers (grey, y = (−2.3 ± 0.3 × 10−6)x + (0.56 ± 0.03), r2 = 0.82, P < 0.001). The intercepts at Fmod = 0 for POCpetro are given with uncertainty (±1 s.d.) and are different for each sub-basin, reflecting the distribution of organic carbon-rich rocks in the Mackenzie mountains40. c, Measured δ13Corg versus those predicted by the endmember mixing model (EMM-predicted) (equations (1) and (2); Methods). The good agreement between measured and predicted values within the uncertainty on the measurements suggests that mixing of POCpetro and POCbiosphere can explain the first-order variability in δ13Corg values between catchments and between suspended load and river bed materials.

Extended Data Figure 3 Radiocarbon age of biospheric particulate organic carbon in the Mackenzie River derived from the mixing analysis.

The number of POCbiosphere measurements of a given range of 14C ages is shown for each sampling location as a narrow rectangle. The distribution of published basal peat sample 14C ages for the Mackenzie River basin25 is shown as wide rectangles.

Extended Data Figure 4 River particulate organic carbon in the Mackenzie basin.

Organic carbon concentration as a function of Al/Si, which is a function of grain size in the Mackenzie River basin26. Analytical errors (2 s.d.) are shown as grey lines if larger than the point size.

Extended Data Figure 5 Stable isotope composition and nitrogen to organic carbon ratio of terrestrial and marine sediments.

Suspended sediments from the Mackenzie River (circles) at the delta (black), Tsiigehtchic (grey) and Norman Wells (white) are shown. Marine sediment samples from the MTW01 sediment core (this study, triangles, black <63 µm, grey >63 µm) are shown with published surface sediment samples from the Beaufort Sea (white triangles) and Davis Strait (black squares)7,29. The terrestrial POC field shows an indicative range of values measured in the Mackenzie River. The marine OC field shows values expected for Arctic Ocean marine OC. Analytical errors (2 s.d.) are shown as grey lines if larger than the point size.

Extended Data Table 1 River suspended sediment and bed material samples from the Mackenzie basin in 2009–2011
Extended Data Table 2 Sediment samples from the offshore core MTW01
Extended Data Table 3 River bank samples from the Mackenzie River in 2009

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Hilton, R., Galy, V., Gaillardet, J. et al. Erosion of organic carbon in the Arctic as a geological carbon dioxide sink. Nature 524, 84–87 (2015). https://doi.org/10.1038/nature14653

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