Salts in the clay playas of China’s arid regions: gone with the wind

Abstract

In China’s arid regions, aeolian salts are transported along with dust aerosols, but their contents and the emission rates are poorly understood. Using samples with undisturbed surfaces and artificially disrupted surfaces (to simulate human disturbances such as reclamation, planting, trampling by animals, and other activities), the transport rates for windblown material and the salt contents of clay playa surfaces were investigated in a wind tunnel. The results showed that under wind velocities ranging from 8 to 22 m/s, wind erosion rates ranged between 0.009 and 0.066 g/m2/s for the undisturbed surfaces and between 0.011 and 0.048 g/m2/s for the artificially disrupted playa surfaces. Although the amount of wind-transported material that was captured was too small to allow an analysis of individual salt contents using the available equipment, electrical conductivity measurements and correlation analysis revealed mean total salt contents of 9.59 g/kg in the transported materials collected above the sealed playa surfaces versus 3.38 g/kg in materials from the same surfaces that were artificially cracked after testing the sealed surfaces. Given the large areas containing clay playas in China’s arid regions, these results will improve our understanding of aeolian salt transport in arid China and will facilitate interpretation of the sources of aeolian salts.