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Title: The significance of carbon-enriched dust for global carbon accounting

item WEBB, NICHOLAS - New Mexico State University
item CHAPPELL, ADRIAN - Commonwealth Scientific And Industrial Research Organisation (CSIRO)
item STRONG, CRAIG - Griffiths University
item MARX, SAMUEL - University Of Wollongong
item MCTAINSH, GRANT - Griffiths University

Submitted to: Global Change Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/5/2012
Publication Date: 12/15/2012
Citation: Webb, N.P., Chappell, A., Strong, C.L., Marx, S.K., McTainsh, G.H. 2012. The significance of carbon-enriched dust for global carbon accounting. Global Change Biology. 18:3275-3278.

Interpretive Summary: Soil organic carbon stores are transient and are influenced by soil erosion. Wind erosion selectively removes soil carbon from eroding sites, resulting in local depletion. This can affect soil health, plant growth and agricultural productivity. When soil carbon is eroded by wind it becomes enriched in dust and can be transported long distances. Current estimates of soil carbon losses to wind erosion have not accounted for its selective removal and enrichment in dust. We show that representing this enrichment will be important for reducing uncertainty in estimates of soil carbon erosion and in carbon accounting systems.

Technical Abstract: Soil carbon stores amount to 54% of the terrestrial carbon pool and twice the atmospheric carbon pool, but soil organic carbon (SOC) can be transient. There is an ongoing debate about whether soils are a net source or sink of carbon, and understanding the role of aeolian processes in SOC erosion, transport and deposition is rudimentary. The impacts of SOC erosion by wind on the global carbon budget, and its importance for carbon accounting remain largely unknown. Current understanding of SOC losses to wind erosion is based on the assumption that the SOC content of eroded material is the same as that of the parent soils. However, measured enrichment factors for the SOC content of Australian dusts relative to parent soils show that the SOC content of dusts can be up to seven times (by weight) larger than that of source-area soils, with enrichment factors ranging from 1.67 to 7.09. Assuming dust emissions from the continent of ~110 Mt yr -l , SOC dust emissions would be 0.13–4.65 Mt SOC yr –l without enrichment but 0.94–7.77 Mt SOC yr-l with enrichment; which represents an uncertainty of around 60%. Representing SOC enrichment within dust emission models will reduce uncertainty in estimates of the impact of wind erosion on SOC flux and provide an approach for the inclusion of wind erosion processes in carbon accounting systems.