Characteristics and seasonal variability of atmospheric deposition in Uljin, adjacent to the southwestern East Sea

Characteristics and amounts of materials supplied by atmospheric deposition to the surface ocean are important on marine ecosystems. We analyzed acidity of the wet deposition as well as concentrations and fluxes of water-soluble ions (WSIs) in the wet and dry deposition, in order to estimate seasonal variability of WSIs and correlations between the acidity and the WSIs. Rainwater and total suspended particles (TSP) were collected weekly or half-weekly on the rooftop of building of the East Sea Research Institute, Uljin, Republic of Korea, the coastal area of the East Sea, from October 2013 for wet deposition samples and March 2014 for the dry deposition samples to April 2016. The WSIs flux ranges of the wet deposition were 0.04-12.79 mmol•m-2•month-1 for dissolved inorganic nitrogen (DIN) as NO3- and NH4+, of which NO3- fluxes accounted for about 56%, 0.01-4.05 for non-sea-salt sulfate (nss-SO42-), and 0.00-1.31 for non-sea-salt calcium (nss-Ca2+). The average concentrations of the dry deposition were 1.93 ± 2.16 μg•m-3 for DIN as NO3-N and NH4+-N, of which NH4+-N accounted for about 56%, 5.04 ± 3.42 for nss-SO42-, and 0.78 ± 0.57 for nss-Ca2+. The seasonal fluxes of WSIs in the wet deposition were highest in summer and lowest in winter except for nss-Ca2+, which showed correlations with the amount of precipitation, while the concentrations of WSIs in the dry deposition were highest in spring and lowest in autumn. Acidity of the rainwater samples were correlated not only with the fluxes of NO3- and nss-SO42-, well-known for acidic ions, but also with those of NH4+.