Acidic precipitation and large-scale transport of air pollutants observed in Korea

Acid rain at a rural site in Chongwon (KHN), central Korea has been under o bservation since 1990. To substantiate the 10-year observations, rain sampl es from six other sites were also collected and analyzed. Results show that acid rain occurred frequently at all sites. At KHN, seasonal and annual va riability of pH values had a 10-year VWM value of 4.67 and an arithmetic me an value of 5.09. In general, a high value of pH occurred during springtime when the occurrence of yellow sand (dust) was prevalent in East Asia; duri ng summer, heavy rain usually contained neutral pH values. During other sea sons, the degree of acidic precipitation usually coincided with certain air flows. Most frequently, air flows and cyclones coming from south and centr al China often resulted in precipitation with low pH values observed in Kor ea. Using daily satellite observations from 1996, we have also been monitoring the long-range and large-scale transport of air pollutants (LSTAP) over Eas t Asia. Many samples of LSTAP were obtained when they were crossing the Yel low Sea and moving over the Korean Peninsula and to SW Japan. The width of the Yellow Sea is ca. 350 similar to 700 Ion and air pollutants take 1 simi lar to2 days to cross it. Cases of acid rain in Korea clearly correlate wit h the LSTAP from source regions in China.