Effects of Asian dust on the atmospheric input of trace elements to the East China Sea

• Elemental concentrations increase significantly during Asian dust events.
• Distinct size distributions for total and soluble fractions of crustal elements.
• Opposite effects of Asian dust on dry deposition of nutrient and toxicant elements.

The long-range transport of Asian dust (AD) can carry large quantities of trace elements to the marginal seas of the Northwest Pacific, and the deposition of soluble fractions of aerosol elements may significantly impact the primary productivity and ecosystem structure. Samples of total suspended particulates (TSP) and size-segregated aerosols were collected synchronously at Huaniao Island in the East China Sea (ECS) between April 2010 and March 2011 and then analyzed for the total and soluble fractions of 14 trace elements. Twelve AD events were identified in the spring and autumn of the sampling year based on official records of AD storms from the China Meteorological Administration and verified by the high Al concentration in the aerosol samples. The dry deposition flux of the total or soluble fraction of each analyzed aerosol element was estimated using its concentration in the TSP samples and dry deposition velocity derived from the size-segregated samples. The dry deposition velocity varied from 0.7 cm s− 1 for total Pb to 1.5 cm s− 1 for total Al based on the mass median diameters (MMD) of 1.6 and 4.9 μm, respectively, of associated particles. During AD events, the mean concentrations of the total and soluble fractions of Al, Fe, Mn, P and Ba increased significantly and led to enhanced dry deposition fluxes of these elements to the ECS (over a factor of 3 for the total and over 30% for the soluble fraction). The concentrations of the soluble fractions of anthropogenically derived elements (As, Cd, Cu, Pb, V and Zn) during AD events were lower than at other times and resulted in lower dry deposition fluxes. Asian dust events were associated with higher than average dry deposition fluxes of soluble Fe and P and lower fluxes of soluble Cu and Zn.