대기 라돈 모니터링 및 시계열 변동 특성: 2006∼2008년 제주도 고산지역 측정

Abstract

The realtime monitoring of radon(222Rn) concentrations for three years of 2006～2008 has been carried out to evaluate the timely variational characteristics of the background level concentrations of atmospheric radon at the Gosan site, Jeju Island. The mean concentration of radon for the studying period was 2,965 mBq/m3, and the annual mean concentrations of each year were in the range of 2,768～3,124 mBq/m3. In seasonal comparison, the order of the seasonal mean concentrations was as winter(3,578 mBq/m3) > fall(3,351 mBq/m3) > spring(2,832 mBq/m3)> summer(2,073 mBq/m3). The monthly mean concentrations were in the order of Jan > Feb > Oct > Nov > Dec > Mar > Sep > Apr > May > Jun > Aug > Jul, and the highest (3,713 mBq/m3) on January was almost twice as the lowest (1,946 mBq/m3) on July. The hourly concentrations in a day showed the highest (3,356 mBq/m3) at around 7 a.m. and the lowest (2,574 mBq/m3) at around 3 p.m., and increased again during nighttime. From the backward trajectory analyses for a continental fetch of radon, the high 10% concentrations of radon matched very much with when the air mass were moved from the north China and the Korean peninsula to Jeju area, whereas the low 10% concentrations have correlated with the air mass movement from the North Pacific Ocean. In comparison by air inflow sectors, the radon concentrations were relatively high on Sector 1 (225°∼337°, China continent) and low on Sector 4 (135°∼225°, north pacific). The radon concentrations have been compared with those of some air pollutants, and they showed a similar pattern with SO2 and NO2 as high in winter and low in summer, whereas a bit different trend to the O3 concentrations. The hourly variation of radon concentrations was quite similar to that of CO as high at 7∼8 a.m. and low at 2∼3 p.m., whereas very opposite to that of O3.