Chemical compositions and particle number densities of atmospheric aerosols were measured in the coastal area of Seto Inland Sea during the spring of 2015. The mean concentrations of NH4+, NO3-, and water-soluble organic nitrogen (ONws) in the total (fine and coarse) particles were 1.6, 0.85, and 0.28 μg N m-3, respectively. Although NO3- existed in fine and coarse particles, while NH4+ and ONws existed primarily in fine particles. The contribution of ONws to the total nitrogen was approximately 10%, however, these fractions are comparable to the contribution of fine NO3- and coarse NH4+.
The dry deposition fluxes of particulate NH4, NO3-, and ONws were 280, 660 and 83 μg N m-2 day-1, respectively. The dry deposition flux of NO3- was more effective than any other nitrogen compounds, since the deposition rate depends upon the size distribution. The dry deposition flux of ONws was approximately 8.1% of nitrogen compounds, however, it is found that ONws should be considered in evaluating the effects of nitrogen compounds on marine ecosystems.