Importance of anthropogenic inputs and continental-derived dust for the distribution and flux of water-soluble nitrogen and phosphorus species in aerosol within the atmosphere over the East China Sea

We analyzed 156 aerosol samples, including 10 dust storm samples, collected from January to December 2005 at a coastal site on the southern East China Sea at Keelung city, Taiwan, for water-soluble major ions, nitrogen, and phosphorus species. In addition, 4-d back trajectories of air masses arriving daily at the sampling site were calculated to determine the potential aerosol source regions. The obtained concentrations of major ions indicate that a continental source was dominant from January to May and from November to December, a local source during July, and an oceanic source from September to October. The measured atmospheric concentrations of nitrogen and phosphorus species show clear seasonal variations and correspond to the different sources and weather conditions. During the dust storm period, dissolved inorganic nitrogen ( DIN) and dissolved inorganic phosphorus ( DIP) concentrations showed statistically significant linear relationships with the amount of aerosol particles, suggesting a continental source. The results of a factor analysis of combined major ions and DIN and DIP indicate that crustal sources, marine sources, and combustion sources are the three major controlling factors during the non-dust-storm period. Natural and anthropogenic land sources and marine sources are the most influential factors in terms of the distribution of aerosol during the dust storm period. A strong correlation was also found between DIN and DIP, indicating similar sources and transportation mechanisms. The results of flux calculations indicate that aerosols derived from dust storms and biomass burning provide 12 +/- 8% and 46 +/- 36% of total DIN and 16 +/- 10% and 46 +/- 38% of total DIP, respectively. Consequently, the inputs of aerosol derived from biomass burning may be an important source of nitrogen and phosphorus in aerosols over the East China Sea.