|This study aims to understand chemical characteristics of wet and dry deposition, and trends of atmospheric concentration and deposition in Korea. To conduct long-term monitoring of acid deposition, rainfall and PM2.5 samples were collected at 38 monitoring sites and analyzed to detect pH, conductivity, and major ionic components including SO₄²?, Cl?, NO₃?, NH₄?, Na?, K?, Ca²? and Mg²?, as well as mass concentration of fine particles (PM<SUB>2.5</SUB>). From the analysis, we can observe the trends of acid deposition, deposition amount of each element, and total acid depositions in Korea.
The volume weighted annual mean pH of precipitation in Korea was 4.9. The volume weighted annual mean concentrations of SO₄²?, NO₃?, Cl? were 2.21, 1.23, 1.39 ㎎/L respectively, indicating that SO₄²? was the major contributor, followed by NO₃? and Cl?. In the case of cation, annual mean concentration for NH₄?, Na?, K?, Ca²?, Mg²?, and H? are 0.66, 0.67, 0.28, 0.15, 0.11, 0.02 ㎎/L. Annual wet deposition rate for SO₄²?, NO₃?, and NH₄? were 2.61, 1.45, 0.77 g/㎡ㆍyr respectively.
The results show that daily averaged mass concentration of PM2.5 is 27.5 ㎍/㎥ and mass concentrations for SO₄²?, NH₄?, and NO₃? are 4.94, 2.00, 2.08 ㎍/㎥ respectively, which account for 18.0%, 7.6% and 7.3% of the total PM2.5 mass concentration individually in the long term monitoring. During the measurement period, deposition velocity for SO₂, HNO₃, aerosol, NO₂, NH₃ was 0.24, 1.42, 0.17, 1.75, 1.75 ㎝/sec. The result shows that annual mean dry deposition rates for SO₂ in 2005~2009 were 0.32, 0.55, 0.56, 0.37, 0.27 S g/㎡ㆍyear, and for HNO₃ were 0.05, 0.11, 0.28, 0.22, 0.20 N g/m²ㆍyear, for NO₂ in 2007~2009 were 0.37, 0.41, 0.35 N g/㎡ㆍyear, and for NH₃ were 0.50, 0.43, and 0.59 N g/㎡ㆍyear.
Dry deposition contributed about 29 percent of the total sulfur deposition, and 65 percent of the total nitrogen deposition. Critical load exceedance was estimated for three years (Oct. 2006~Oct. 2009) using mean depositions of nitrogen and sulfur, which shows that the impact of nitrogen was relatively higher than that of sulfur in the capital region and west coastal regions.