Atmospheric nitrate, sulfate, ammonium and calcium concentrations in China

We used teflon/nylon filter packs to measure concentrations of nitrate (aerosol plus vapor),sulfate, ammonium, and calcium at three locations in China during October of 1985. On theaverage, molar sulfate concentrations were less than twice the total nitrate concentrations.This small ratio is somewhat surprising, in view of the large amount of coal burning in China.In Beijing, calcium was the dominant cation, but at both the Xinglong AstronomicalObservatory (a rural northern China site) and Changsha (the capital city of Hunan Province,in the south), there was more ammonium ion than calcium in the aerosol. During a period ofnortherly winds at Xinglong, the concentrations were comparable to reported backgroundvalues fiom North America and Europe, suggesting that this may be a good site for studying.4sian continental background air.