Location: Range Management ResearchTitle: Soil organic carbon enrichment of dust emissions: Magnitude, mechanisms and its implications for the carbon cycle) Author
Submitted to: Earth Surface Processes and Landforms
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/30/2013
Publication Date: 11/1/2013
Publication URL: handle.nal.usda.gov/10113/58357
Citation: Webb, N., Strong, C., Chappell, A., Marx, S., McTainsh, G. 2013. Soil organic carbon enrichment of dust emissions: Magnitude, mechanisms and its implications for the carbon cycle. Earth Surface Processes and Landforms. 38:1662-1671. Interpretive Summary: Understanding how soil carbon is eroded by wind and the processes by which it is selectively removed from the soil surface and enriched in dust will be important for quantifying the impacts of wind erosion on soil carbon stores. This paper examines the soil organic carbon content of dust emissions from the Australian rangelands. It identifies that sandy or loose particulate soils are more efficient at releasing and enriching soil organic carbon in dust than aggregated clay soils. Sorting of soil organic carbon and mineral grains during dust transport may lead to further enrichment of dust emissions and areas where dust is deposited downwind.
Technical Abstract: Soil erosion is an important component of the global carbon cycle. However, little attention has been given to the role of aeolian processes in influencing soil organic carbon (SOC) flux and the release of greenhouse gasses, such as carbon-dioxide (CO2), to the atmosphere. Understanding the magnitude and mechanisms of SOC enrichment in dust emissions is necessary to evaluate the impact of wind erosion on the carbon cycle. This research examines the SOC content and enrichment of dust emissions measured using Big Spring Number Eight (BSNE) wind-vane samplers across five land types in the rangelands of western Queensland, Australia. Our results show that sandy soils and finer particulate quartz-rich soils are more efficient at SOC emission and have larger SOC dust enrichment than clay-rich aggregated soils. The SOC enrichment ratios of dusts originating from sites with sand-rich soil ranged from 2.1-41.9, while the mean enrichment ratio for dusts originating from the clay soil was 2.1. We hypothesise that stronger inter-particle bonds and the low grain density of the aggregated clay soil explain its reduced capacity to release SOC during saltation, relative to the particulate sandy soils. We also show that size-selective sorting of SOC during transport may lead to further enrichment of SOC dust emissions. Two dust samples from regional transport events were found to contain 15-20% SOC. These preliminary results provide impetus for additional research into dust SOC enrichment processes to elucidate the impact of wind erosion on SOC flux and reduce uncertainty about the role of soil erosion in the global carbon cycle.