Flux and composition of wind-eroded dust from different landscapes of an arid inland river basin in north-western China

Using a simple æolian dust sampler, dust plumes generated from five landscape types (dry lakebed, gobi, farmland, seriously degraded grassland and sandy desert lands) in the inland basin of the Heihe River of north-western China, were monitored, along with wind velocity and temperature, from 2 April to 30 May 2001. Dust fluxes, conditions under which they occurred and an elemental analysis (Na, Mg, Al, Si, S, Cl, K, Ca, Ti, Fe) of the æolian dust were completed. While one might have expected the sandy desert land to contribute the greatest quantity of æolian dust, it was the dried terminal lakebed and degraded grasslands, with April dust productions of 29.37 and 23.54 g d−1, respectively, which outproduced other landscapes by 10–16-fold. The chemical composition of dust differed according to the location of sampling within the Heihe basin, with lower Si and Al, and higher Mg, Na, Cl and S contents occurring in the lower reaches due to presence of high-salt lake sediments. In the spring, under the prevailing conditions of low soil moisture contents, daily mean wind velocities over 4.0 m s−1, maximum wind velocities over 12.0 m s−1, and daily maximum air temperatures of over 15°C, almost any landscape can produce æolian dust. Indeed, this is when the majority of dust storms occur in the arid region. Protecting grasslands in the lower reaches of the Heihe River basin from degradation and rehabilitating the dried-up terminal lake would do much to reduce æolian losses in the region.