Concentrations of PM_(10), PM_(2.5), and PM_1 influenced by atmospheric circulation and atmospheric boundary layer in the Korean mountainous coast during a duststorm

摘要

Particle size concentrations of 100 ng m~(-3) to 20 μg m~(-3) were measured at two sampling points over the eastern coastal region of Korea by two GRIMM aerosol samplers from March 7-17, 2004. One sampling point was located on the western upwind side of the mountains, and the other sampling point was located in the city of Kangnung in the coastal basin downwind and adjacent to the East Sea. Concentrations of PM_(10), PM_(2.5), and PM] were measured near the ground in Kangnung on March 8,2004, until 1200 LST before the passage of a duststorm. Values of about 40, 35, and 30 μg m~(-3), respectively, were detected indicating little variation among sample concentrations. Before the duststorm, maximum concentrations for PM_(10) occurred around 0800 and 1700 LST due to increased fuel combustion from road vehicles. From the afternoon of March 10-16 when the largest amount of dust from China had passed over Kangnung under the influence of a westerly wind, PM_(10) concentration reached 340 μg m~(-3), and PM_(2.5) and PM_1 concentrations reached 105 μg m~(-30) and 60 μg m~(-3), respectively, indicating double the PM_(10) concentration as compared to PM_(2.5). Most of the dust transported from China consisted of particle sizes larger than PM_(2.5) and PM_1. Dust transported from the western, upwind side of the mountains combined with the particulates emitted from road vehicles and industrial and residential boilers in the city after sunrise under the influence of westerly winds resulted in a high paniculate concentration at 0900 LST. However, a low concentration of particulates in the city was detected near 1200 LST due to changes in the structure of the atmospheric boundary layer, while a high concentration over the mountains occurred due to a stable layer. High-particulate concentrations in the city occurred again after 1700 LST owing to increased fuel combustion from road vehicles and residential boilers, as well as transport of dust particles from China. Paniculate from China was transported through the upwind side of the mountains by westerly, land-mountain breezes directed toward the city and a decreased depth in the boundary layer over the city with a maximum concentration at 2200 LST. Paniculate matter concentrations of all sizes were generally higher over the mountains than in the city due to a much shallower boundary layer.