제주도 고산지역의 대기 라돈 배경농도 및 시계열 변동

The background level and timely variation characteristics of atmospheric 222 Rn concentrations have been evaluated by the real time monitoring at Gosan site of Jeju Island, Korea, during 2008~2015. The average concentration of atmospheric radon was 2,480 mBq m -3 for the study period. The cyclic seasonality of radon was characterized such as winter maximum and summer minimum, consistent with the reduction in terrestrial fetch going to summer. On monthly variations of radon, the mean concentration in October was the highest as 3,041 mBq m -3 , almost twice as that in July (1,481 mBq m -3 ). The diurnal radon concentrations increased throughout the nighttime approaching to the maximum (2,819 mBq m-3) at around 7 a.m., and then gradually decreased throughout the daytime by the minimum (2,069 mBq m -3 ) at around 3 p.m. The diurnal radon cycle in winter showed comparatively small amplitude due to little variability in atmospheric mixing depth, conversely, large amplitude was observed in summer due to relatively a big change in atmospheric mixing depth. The cluster back-trajectories of air masses showed that the high radon events occurred by the predominant continental fetch over through Asia continent, and the radon concentrations from China continent were about 1.9 times higher on the whole than those from the North Pacific Ocean. The concentrations of PM 10 also increased in proportion to the high radon concentrations, showing a good linear correlation between PM 10 and radon concentrations.