|This study is aimed at finding the characteristics of long-term trends in wet and dry deposition in Korea. NIER(National Institute of Environmental Research) has monitored major ion components of wet and dry deposition since 1999. The institute also has carried out researches in order to estimate the critical loads for ecosystem based on the collected data from 1999 to 2009. Sampling was conducted at 38 acid deposition monitoring sites and major ion components such as SO₄²?, Cl?, NO₃?, NH₄?, Na?, K?, Ca²? and Mg²? were analyzed by using ion chromatograph. The results helped find out changes in acid deposition for ten years(1999∼2009) in Korea. The data from 10 monitoring sites showed that average annual pH for the monitoring period was 5.1 with the maximum pH level of 6.2 in Imsil(2007) and its minimum level of 4.2 in Deajeon(2008). Of 10 monitoring sites, pH levels of Gwangju, Daejeon, Seoul, Taean and Gangwha have decreased and there was not much change of pH in rural areas.
The total deposition of sulfur showed a decreasing trend of 1.44, 1.89, 2.02, 1.26, 1.33, 1.28 g/㎡ㆍyear from 2005 to 2010 while the total deposition of nitrogen was 1.29, 1.72, 2.58, 2.14, 2.49, 2.31 g/㎡ㆍyear during the same period showing an increasing trend. Sulfur concentration was lower in 2008 and 2009 compared to that of 2006 and 2007 and, in particular, the concentration monitored at Seoul was slightly higher than others. As for nitrogen, its concentration was observed to be high in some part of the Seoul Metropolitan Area(SMA) and low in 2009.