Potential Dust Emissions from Sources in the Southern Hemisphere.

Abstract:

The Southern Hemisphere currently exhibits low levels of atmospheric dust concentrations relative to the Northern Hemisphere. Recent research suggests that dust concentrations could, however, increase as a result of loss of vegetation cover in the Southern Kalahari and the Mallee. Disturbances resulting from grazing and agriculture are identified as such drivers of land use change in these regions. While studies on the importance of atmospheric dust in global-scale processes are abundant, little has been done to locate the potential dust sources in the Southern Hemisphere because potential new sources are by definition inactive and are undetected in satellite images. To this end, using a combination of laboratory experiments and field observations, we assess that the sediments collected from the dunefields in the Southern Kalahari and Mallee can emit substantial amount of dust, are rich in soluble iron and dust from these sources would reach the Southern Ocean. It is suggested that the supply of soluble iron through atmospheric dust deposition limits the productivity of the Southern Ocean. Thus intensification of land use can potentially make these regions an important source of iron given their proximity to the Southern Ocean. This iron-rich dust could stimulate ocean productivity in future as more areas are reactivated as a result of land-use and droughts.