Characterization and temporal variation of Asian dust aerosol from a site in the northern Chinese deserts

Time series for total aerosol mass and the concentrations of nineteen elements, and the mass particle-size distributions of the elements, were determined for samples collected from a site in the northern deserts of China -Zhenbeitai, one of ground sites of the Asia-Pacific Regional Aerosol Characterization Experiment (ACE-Asia). Nine dust storm (DS) events were observed during the spring of 2001, lasting a combined total of twenty-six days. Peak mass loadings greatly exceeded the average (260 μg m^-3), and higher than average dust-element concentrations and wind speeds were also observed during the three-month study. Material balance calculations showed that ∼82% mass of the total aerosol particles could be ascribed to Asian dust, of which Al, Ca, Fe, K, Mn, Si and Ti accounted for 7%, 6%, 4%, 2%, 0.1%, 32% and 1% by weight, respectively. Modelcalculated dry deposition velocities for 7 dust-elements during dust storm periods averaged 17 cm s^-1 and ranged from 14 to 21 cm s^-1. The estimated dry depositiona of Asian dust for the spring of 2001 was 189 g m^-2, of which 85% was due to dust storms. Factor analysis indicated that ∼89% of the dust loading during this period was due to remote or regional transport; ∼11% to local or background dust.