Temporal and spatial distributions of dust and its deposition to the China Sea

Abstract

Atmospheric concentrations of aluminum, an indicator of dust substances, have been determined in a set of high-volume aerosol particle samples collected at different locations over continental China and over the China Sea. High concentrations of dust were observed in northern continental China, and at certain locations such as Beijing dust may include an anthropogenic fraction. The mass particle-size distributions of dust varied depending on its distance from source regions, with the mass median diameter for Al of ∼ 1.6-5.9 μm at Beijing in northern China and ∼ 1.9 μm over off-shore areas of the East China Sea. Model-predicted mean dry deposition velocities of dust particles are from 1.4 to 4.8 cms-1 over northern continental China and from 1.4 to 2.1 cm s-1 over the China Sea. Atmospheric deposition models have been applied to estimate the atmospheric fluxes and deposition of dust at different locations. The estimated atmospheric flux of dust at Xi'an of the Loess Plateau is 25 (4.9 to 44) g m-2 mo-1 which is the highest among the regions we studied. The estimated present-day dust flux is comparable to the late quaternary records of eolian dust accumulation at this site. The total atmospheric deposition of dust to the China Sea is 67 Tg yr-1, accounting for 14% of the total atmospheric deposition of dust to the entire North Pacific. With such a high deposition rate, Asian dust may play an important role in biogeochemical cycles of trace substances in the Asia/North Pacific region.