Dust producing soil types of the Mallee region, south-east Australia
1, John Leys2, Craig Strong3, Grant McTainsh1
1Griffith University, Brisbane, QLD, Australia, 2New South Wales Office of Environment and Heritage, Gunnedah, NSW, Australia, 3Fenner School of Environment and Society, ANU, Canberra, ACT, Australia
Wind erosion is an important agent of landscape change in arid and semi-arid regions, and dust storms have the capacity to move millions of tonnes of dust over vast distances. The Mallee Region, surrounding Mildura is a major source area of dusts within Australia’s South East dust path. Monitoring of dust concentrations at Mildura and other sites within the Mallee has provided understanding of dust event occurrence and frequency. However, there is limited knowledge of what soil types within the Mallee region are actually producing dust.
In this study, dust events in the Mallee are analysed over 15 dust storm years (1990-2007) and the dusts are compared with soil that are representative of the major soil types in the area. QEMSCANÒ (SEM) technology is used to measure soil and dust mineralogy, and a Coulter Multisizer is used to measure particle size characteristics and particle aggregation. The identification of dust-producing soil types is based upon mineral and particle size correlations between soils and dusts. The Dust Production Potential (DPP) of these soils is a qualitative measure based upon soil particle size and aggregation characteristics.
Results show that Calcareous Earth soils have the highest DPP and are the most likely source soils of dust in the Mallee, as they have the highest correlation with dust events. Sandplain and Red Dune soils have a moderate to low DPP, and lower correlation with dust events, but their role as source soils is increased because they occur at higher elevations. Floodplain and Lakebed soils have high DPP, but are seldom correlated with dust events. Further research should focus on the spatial distribution and land management aspects of these soils.