Calcification-driven CO2 emissions exceed “Blue Carbon” sequestration in a carbonate seagrass meadow
Van Dam, B.R.; Zeller, M.A.; Lopes, C.; Smyth, A.R.; Böttcher, M.E.; Osburn, C.L.; Zimmerman, T.; Pröfrock, D.; Fourqurean, J.W.; Thomas, H. (2021). Calcification-driven CO2 emissions exceed “Blue Carbon” sequestration in a carbonate seagrass meadow. Science Advances 7(51): eabj1372. https://dx.doi.org/10.1126/sciadv.abj1372
In: Science Advances. AAAS: New York. e-ISSN 2375-2548, more
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| Authors | | Top |
- Van Dam, B.R.
- Zeller, M.A.
- Lopes, C.
- Smyth, A.R.
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- Böttcher, M.E.
- Osburn, C.L.
- Zimmerman, T.
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- Pröfrock, D.
- Fourqurean, J.W.
- Thomas, H., more
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| Abstract |
Long-term “Blue Carbon” burial in seagrass meadows is complicated by other carbon and alkalinity exchanges that shape net carbon sequestration. We measured a suite of such processes, including denitrification, sulfur, and inorganic carbon cycling, and assessed their impact on air-water CO2 exchange in a typical seagrass meadow underlain by carbonate sediments. Eddy covariance measurements reveal a consistent source of CO2 to the atmosphere at an average rate of 610 ± 990 μmol m−2 hour−1 during our study and 700 ± 660 μmol m−2 hour−1 (6.1 mol m−2 year−1) over an annual cycle. Net alkalinity consumption by ecosystem calcification explains >95% of the observed CO2 emissions, far exceeding organic carbon burial and anaerobic alkalinity generation. We argue that the net carbon sequestration potential of seagrass meadows may be overestimated if calcification-induced CO2 emissions are not accounted for, especially in regions where calcification rates exceed net primary production and burial. |
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