Sources, compositions, and distributions of water-soluble organic nitrogen in aerosols over the China Sea

Particulate water-soluble organic nitrogen (ON) was measured over the South China Sea, the Yellow Sea and at a coastal site at Qingdao in spring 2005 and 2006 to study its impact on the oceanic ecosystem over the China sea. ON contributed ∼30% of the total water-soluble particulate nitrogen over the South China Sea and ∼20% over the Yellow Sea and in Qingdao. More than 70% of the ON existed in the fine mode particles (<2.1 μm). During dust-storm events, ON in the coarse particles (>2.1 μm) increased leading to an increase of that in total suspended particulates (TSP). Factor analysis indicated that ON mainly originated from anthropogenic sources while a relatively small amount was from marine and crustal sources. Urea, on the average, represented ∼8% of the total ON over the marginal sea of China. In the non-dust aerosols, ∼50% of urea existed in the fine mode over the Yellow Sea and Qingdao, but the percentage decreased to ∼30% in the dust aerosols. Free amino acids were generally a minor component of the ON, only accounting for ∼1% of the total ON.