Publication Date:
2022-05-25
Description:
Author Posting. ยฉ The Author(s), 2015. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature 524 (2015): 84-87, doi:10.1038/nature14653.
Description:
Soils of the northern high latitudes store carbon over millennial timescales (103 yrs) and
contain approximately double the carbon stock of the atmosphere1-3. Warming and
associated permafrost thaw can expose soil organic carbon and result in mineralisation
and carbon dioxide (CO2) release4-6. However, some of this soil organic carbon may be
eroded and transferred to rivers7-9. If it escapes degradation during river transport and
is buried in marine sediments, then it can contribute to a longer-term (โช104 yrs),
geological CO2 sink8-10. 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 POC source 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 26 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 5800ยฑ800 yr, much older than large
tropical rivers13,14. Based on the measured biospheric POC content and variability in
annual sediment yield15, we calculate a biospheric POC flux of ๐. ๐๐โ๐๐.๐๐
+๐๐.๐๐ TgC yr-1 from
the Mackenzie River, three times the CO2 drawdown by silicate weathering16. Offshore
we find evidence for efficient terrestrial organic carbon burial over the Holocene,
suggesting that erosion of organic carbon-rich, high latitude soils may result in a
significant geological CO2 sink.
Description:
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.
Description:
2016-02-05
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
application/pdf
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