Dust Deposition and the Burial of Organic Carbon

Understanding the behavior of the carbon cycle necessitates analyzing the differing processes involved in the production, transport, and eventual preservation of organic carbon in marine sediments. To quantify the potential role of dust in these processes, we propose a connection between dust fluxes to the ocean and the physical protection of organic matter in ocean sediments. Previous work suggests a linear relationship between the preservation of organic matter and mineral surface area [4]. Assuming that dust contributes to this mineral fraction, we calculate the organic carbon that would be associated with its surface area. We find that the organic matter associated with dust would be about 10% of the total organic carbon buried in ocean sediments. This finding is consistent both with global sedimentation rates [3] and with recent work based on marine particle flux data [1,2]. Our work suggests a potential connection between the physical protection of organic matter and the associations found between the lithogenic and organic carbon fluxes in the ocean [1]. It also strengthens the idea that large perturbations to dust fluxes could directly impact carbon dioxide levels in the atmosphere. [1] R.A. Armstrong, C. Lee, J.I. Hedges, S. Honjo, and S.G. Wakeham. A new, mechanistic model for organic carbon fluxes in the ocean based on the quantitative association of POC with ballast minerals. Deep-Sea Research Part II, 49(1-3):219--236, 2001. [2] J.P. Dunne, J.L. Sarmiento, and A. Gnanadesikan. A synthesis of global particle export from the surface ocean and cycling through the ocean interior and on the seafloor. Global Biogeochem. Cycles, 21, 2007. [3] R.A. Jahnke. The global ocean flux of particulate organic carbon: Areal distribution and magnitude. Global Biogeochem. Cycles, 10:71--88, 1996. [4] L.M. Mayer. Surface area control of organic carbon accumulation in continental shelf sediments. Geochim. Cosmochim. Acta, 58(4):1271--1284, 1994.