Arctic soil microbes are not consuming ancient soil carbon: Implications for depositional environments, Canada, 2011
Vast quantities of Arctic soil carbon may become susceptible to microbial degradation due to thawing of ancient permafrost. Given that estimates of the vulnerability of Arctic soil carbon are highly variability, an enduring question is how much of the 1500 petagram Arctic soil carbon pool may be con...
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| Format: | Dataset |
| Language: | English |
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Arctic Data Center
2019
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| Online Access: | https://dx.doi.org/10.18739/a2ns0kx7h https://arcticdata.io/catalog/#view/doi:10.18739/A2NS0KX7H |
| Summary: | Vast quantities of Arctic soil carbon may become susceptible to microbial degradation due to thawing of ancient permafrost. Given that estimates of the vulnerability of Arctic soil carbon are highly variability, an enduring question is how much of the 1500 petagram Arctic soil carbon pool may be consumed by soil microbes and thus released as a positive feedback to climatic warming. Here we provide evidence that microbes inhabiting ancient high Arctic soils are not consuming soil organic carbon and therefore only a small portion of the soil carbon may be labile. Using radiocarbon, we measured the composition of the soil carbon and compared this to the carbon being used by the viable microbial community. High Arctic soils were found to overall contain old carbon, however the dominant carbon sources to the microbial community were modern carbon sources. Chemical fractionation of the soil organic carbon illustrated that the soils were highly isotopically heterogeneous and only a small portion of the soil contained young or actively cycling carbon. We propose that soil organic carbon pools in these ancient high Arctic soils are composed of pre-aged carbon that is not susceptible to microbial degradation and that microbes are instead utilizing carbon recently fixed by surface plants.. Although more extensive sampling is required to verify whether this process is widespread in other Arctic and non-Arctic terrestrial depositional environments, our results provide new understanding of the carbon cycling in depositional soils and open the possibility that geologic inputs of carbon may sequester carbon rather than returning it to the atmosphere. |
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