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dc.contributor.authorLengger, Sen
dc.contributor.authorRush, Den
dc.contributor.authorMayser, JPen
dc.contributor.authorBlewett, Jen
dc.contributor.authorSchwartz-Narbonne, Ren
dc.contributor.authorTalbot, Hen
dc.contributor.authorMiddelburg, Jen
dc.contributor.authorJetten, Men
dc.contributor.authorSchouten, Sen
dc.contributor.authorDamste, Jen
dc.contributor.authorPancost, RDen

In response to rising CO2 concentrations and increasing global sea surface temperatures, oxygen minimum zones (OMZ), or “dead zones”, are expected to expand. OMZs are fueled by high primary productivity, resulting in enhanced biological oxygen demand at depth, subsequent oxygen depletion, and attenuation of remineralization. This results in the deposition of organic carbon-rich sediments. Carbon drawdown is estimated by biogeochemical models; however, a major process is ignored: carbon fixation in the mid- and lower water column. Here, we show that chemoautotrophic carbon fixation is important in the Arabian Sea OMZ; and manifests in a 13C-depleted signature of sedimentary organic carbon. We determined the δ13C values of SOM deposited in close spatial proximity but over a steep bottom-water oxygen gradient, and the δ13C composition of biomarkers of chemoautotrophic bacteria capable of anaerobic ammonia oxidation (anammox). Isotope mixing models show that detritus from anammox bacteria or other chemoautotrophs likely forms a substantial part of the organic matter deposited within the Arabian Sea OMZ (~17%), implying that the contribution of chemoautotrophs to settling organic matter is exported to the sediment. This has implications for the evaluation of past, and future, OMZs: biogeochemical models that operate on the assumption that all sinking organic matter is photosynthetically derived, without new addition of carbon, could significantly underestimate the extent of remineralization. Oxygen demand in oxygen minimum zones could thus be higher than projections suggest, leading to a more intense expansion of OMZs than expected.

dc.publisherCenter for Open Scienceen
dc.titleDark carbon fixation contributes to sedimentary organic carbon in the Arabian Sea oxygen minimum zoneen
dc.typeJournal Article
plymouth.organisational-group/Plymouth/Faculty of Science and Engineering
plymouth.organisational-group/Plymouth/Faculty of Science and Engineering/School of Geography, Earth and Environmental Sciences
plymouth.organisational-group/Plymouth/REF 2021 Researchers by UoA
plymouth.organisational-group/Plymouth/REF 2021 Researchers by UoA/UoA07 Earth Systems and Environmental Sciences
plymouth.organisational-group/Plymouth/Users by role
plymouth.organisational-group/Plymouth/Users by role/Academics
dc.rights.embargoperiodNot knownen
rioxxterms.typeJournal Article/Reviewen

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