title: Soil organic carbon dust emission: an omitted global source of atmospheric CO2.
abstract: Soil erosion redistributes soil organic carbon (SOC) within terrestrial ecosystems, to the atmosphere and oceans. Dust export is an essential component of the carbon (C) and carbon dioxide (CO(2)) budget because wind erosion contributes to the C cycle by removing selectively SOC from vast areas and transporting C dust quickly offshore; augmenting the net loss of C from terrestrial systems. However, the contribution of wind erosion to rates of C release and sequestration is poorly understood. Here, we describe how SOC dust emission is omitted from national C accounting, is an underestimated source of CO(2) and may accelerate SOC decomposition. Similarly, long dust residence times in the unshielded atmospheric environment may considerably increase CO(2) emission. We developed a first approximation to SOC enrichment for a well-established dust emission model and quantified SOC dust emission for Australia (5.83 Tg CO(2)-e yr(-1)) and Australian agricultural soils (0.4 Tg CO(2)-e yr(-1)). These amount to underestimates for CO(2) emissions of ≈10% from combined C pools in Australia (year = 2000), ≈5% from Australian Rangelands and ≈3% of Australian Agricultural Soils by Kyoto Accounting. Northern hemisphere countries with greater dust emission than Australia are also likely to have much larger SOC dust emission. Therefore, omission of SOC dust emission likely represents a considerable underestimate from those nations' C accounts. We suggest that the omission of SOC dust emission from C cycling and C accounting is a significant global source of uncertainty. Tracing the fate of wind-eroded SOC in the dust cycle is therefore essential to quantify the release of CO(2) from SOC dust to the atmosphere and the contribution of SOC deposition to downwind C sinks.
authors.affiliation: CSIRO Sustainable Agriculture National Research Flagship, CSIRO Land and Water, GPO Box 1666, Canberra, ACT, 2601, Australia.
authors.forename: Adrian
authors.initials: A
authors.lastname: Chappell
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Webb
authors.forename: Harry J
authors.initials: HJ
authors.lastname: Butler
authors.forename: Craig L
authors.initials: CL
authors.lastname: Strong
authors.forename: Grant H
authors.initials: GH
authors.lastname: McTainsh
authors.forename: John F
authors.initials: JF
authors.lastname: Leys
authors.forename: Raphael A
authors.initials: RA
authors.lastname: Viscarra Rossel
mesh_terms: D001315:Australia; D002244:Carbon / Q000032:analysis*; D002245:Carbon Dioxide / Q000032:analysis*; D004391:Dust / Q000032:analysis*; D008962:Models, Theoretical; D012987:Soil / Q000737:chemistry*; D062211:Spatio-Temporal Analysis; D014919:Wind
chemical_list: D004391:Dust; D012987:Soil; D002245:Carbon Dioxide; D002244:Carbon
keywords: Australia; carbon accounting; carbon budgets; carbon dioxide; dust emission; soil organic carbon