Atmospheric non‐sea‐salt sulfate, nitrate and methanesulfonate over the China Sea

Abstract

To characterize atmospheric particulate non‐sea‐salt (nss) sulfate, nitrate, methanesulfonate (MSA), and selected trace elements over the China Sea, aerosol sampling was conducted at Qingdao and Xiamen, which are on the coast of China, and over offshore regions of the East China Sea. The atmospheric concentrations of nss sulfate and nitrate were much higher along the coast of the China Sea than over remote oceans, with mean values of 10 to 12 μg m−3 for nss sulfate and 5.6 to 7.7 μg m−3 for nitrate. The mean concentrations of atmospheric MSA ranged from 0.029 to 0.066 μg m−3 over the China Sea; these are comparable to values from other coastal sites and remote oceans. Both MSA and nss sulfate are concentrated in particles ≤0.5 μm in diameter, while nitrate shows a bimodel distribution. There was no clear correlation between nss sulfate and MSA concentrations, with the ratios of nss sulfate to MSA (60–870) being substantially higher than those over remote oceans. Based on a biogenic nss‐sulfate/MSA ratio of 18 obtained from the remote North Pacific, the estimated anthropogenic sulfate accounts for 81–97% of the total nss sulfate over the China Sea. Results of factor analyses suggest that coal combustion is the dominate source for anthropogenic sulfate over the basin of the China Sea. Oil combustion appears to be an additional important contributor for anthropogenic sulfate in the region of the East China Sea, but this feature does not exist in the South China Sea region. Pyrometallurgical nonferrous metal smelting is among the additional sources for nss sulfate in this region.