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Soil organic carbon dust emission: an omitted global source of atmospheric CO2.

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Bibliographic Details
Title:	Soil organic carbon dust emission: an omitted global source of atmospheric CO2.
Authors:	Chappell, Adrian¹, Webb, Nicholas P.², Butler, Harry J.³, Strong, Craig L.⁴, McTainsh, Grant H.⁴, Leys, John F.^4,5, Viscarra Rossel, Raphael A.¹
Source:	Global Change Biology. Oct2013, Vol. 19 Issue 10, p3238-3244. 7p. 1 Color Photograph, 1 Chart, 1 Graph, 1 Map.
Subject Terms:	Soil erosion, Carbon in soils, Atmospheric carbon dioxide, Sinks (Atmospheric chemistry), *Sedimentation & deposition
Geographic Terms:	Australia
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 ( CO2) 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 CO2 and may accelerate SOC decomposition. Similarly, long dust residence times in the unshielded atmospheric environment may considerably increase CO2 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 CO2-e yr−1) and Australian agricultural soils (0.4 Tg CO2-e yr−1). These amount to underestimates for CO2 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 CO2 from SOC dust to the atmosphere and the contribution of SOC deposition to downwind C sinks. [ABSTRACT FROM AUTHOR]
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Database:	GreenFILE

Description
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 ( CO2) 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 CO2 and may accelerate SOC decomposition. Similarly, long dust residence times in the unshielded atmospheric environment may considerably increase CO2 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 CO2-e yr−1) and Australian agricultural soils (0.4 Tg CO2-e yr−1). These amount to underestimates for CO2 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 CO2 from SOC dust to the atmosphere and the contribution of SOC deposition to downwind C sinks. [ABSTRACT FROM AUTHOR]
ISSN:	13541013
DOI:	10.1111/gcb.12305