Relationships between grain size and organic carbon 14C heterogeneity in continental margin sediments

Bao, R., Blattmann, T. M., McIntyre, C. , Zhao, M. and Eglinton, T. I. (2019) Relationships between grain size and organic carbon 14C heterogeneity in continental margin sediments. Earth and Planetary Science Letters, 505, pp. 76-85. (doi: 10.1016/j.epsl.2018.10.013)

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The deposition and long-term burial of sedimentary organic matter (OM) on continental margins comprises a fundamental component of the global carbon cycle. A key unknown in interpretation of carbon isotope records of sedimentary OM is the extent to which OM accumulating in continental shelf and slope sediments is influenced by dispersal and redistribution processes. Here, we present results from an extensive survey of organic carbon (OC) characteristics of grain size fractions (ranging from <20 to 250 μm) retrieved from Chinese marginal sea surface sediments in order to assess the extent to which the abundance and isotope composition of OM in shallow shelf seas is influenced by hydrodynamic processes. Our findings show that contrasting relationships exist between 14C contents of OC and grain size in surface sediments associated with two different hydrodynamic modes, suggesting that transport pathways and mechanisms imparted by the different hydrodynamic conditions exert a strong influence on 14C contents of OM in continental shelf sediments. In deeper regions and erosional areas, we infer that bedload transport exerts the strongest influence on (decreases) OC 14C contents of the coarser fraction, while resuspension processes induce OC 14C depletion of intermediate grain size fractions in shallow inner-shelf settings. We use the inter-fraction spread in C values, defined here as , to argue that the hydrodynamic processes amplify overall 14C heterogeneity within corresponding bulk sediment samples. The magnitude and footprint of this heterogeneity carries implications for our understanding of carbon cycling in shallow marginal seas.

Item Type:Articles
Additional Information:This study was supported by SNF “CAPS-LOCK” project 200021_140850 (T.I.E.), by the National Natural Science Foundation of China (Grant No. 41520104009 and No. U1706219, M.Z.) and by “111” project (B13030).
Glasgow Author(s) Enlighten ID:Mcintyre, Dr Cameron
Authors: Bao, R., Blattmann, T. M., McIntyre, C., Zhao, M., and Eglinton, T. I.
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Earth and Planetary Science Letters
ISSN (Online):1385-013X
Published Online:25 October 2018
Copyright Holders:Copyright © 2018 The Authors
First Published:First published in Earth and Planetary Science Letters 505:76-85
Publisher Policy:Reproduced under a Creative Commons License

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