Organic nitrogen in rain and aerosol in the eastern Mediterranean atmosphere: An association with atmospheric dust

From March through early May of 2000, rain and bulk aerosol samples were collected at a coastal site on the eastern Mediterranean Sea at Erdemli, Turkey, and analyzed for nitrogen (N) species, including nitrate (NO3−), nitrite (NO2−), ammonium (NH4+), water‐soluble organic N, urea, and dissolved free amino acids. Other ions were also analyzed, including Ca2+, Mg2+, K+, Na+, Cl−, and SO42−. Water‐soluble organic N was found to contribute ∼17% and ∼26% of the total water‐soluble N in rain and aerosols, respectively. Organic N concentrations within rain and aerosols exhibited statistically significant linear relationships to Ca2+ ion (Rsqr ∼ 0.75, P < 0.05), suggesting a relationship to calcite (CaCO3) in atmospheric dust. Kinematic trajectory analyses indicated the origin of winds from arid regions, mainly in northern Africa, in 70% of the aerosols sampled. Earth Probe/Total Ozone Mapping Spectrometer aerosol index data also confirmed the influence of atmospheric dust in the region on days when Ca2+ concentrations were elevated, and trajectory analyses suggested northern Africa as a source region. The combined ion, trajectory, and aerosol index data suggest that organic N is associated with atmospheric dust in this region. Urea N and amino N represented a small percentage of the organic N fraction. In rain and aerosols, urea represented ∼11% and