Observation of fine particle concentration and its chemical characteristics in central region of Korea during KORUS-AQ pre-campaign

Abstract:

The Central Region super site is one of the 6 super sites operated in Korean peninsula by Ministry of Environment Korea and monitor air quality of central district of Korea continuously and intensively. Located 160km south of Seoul, this site represents an urban site surrounded by residential, commercial area and an 8-lane road cross section which is one of the most crowed main roads in this area. This site also plays a significant role especially in tracing air pollutants flowing through the West Sea from China.

During Korus-AQ(Korea-US Air Quality Study) pre-campaign conducted from 18^th May to 12^th June, PM_2.5 and PM₁₀ mass concentration using BAM1020 (MetOne), PM_2.5bounded ion concentration using AIM (URG), metal concentrations using XRF (Cooper), organic and elemental carbon contents using SOCEC (Sunset), light scattering coefficient using Nephelometer (TSI) and meteorological parameters were continuously measured at this super site.

PM_2.5 and PM₁₀ average concentrations were 31 and 49 ug/m³ with 0.63 fine to course ratio, which were relatively lower than those of annual average concentration of 2014 (39 and 58 ug/m³, respectively). The chemical composition of PM_2.5 were determined as ion(46%), TC(37%), CM(2%), TM(0.1%) and unknown(15%). The average concentration of organic and elemental carbon were 5.6 and 1.8 ug/m³ which were similar lever to average of 2014 (5.9 ug/m³, 1.71 ug/m³, respectively). And the metal concentration including Pb(12.5 ng/m³), Fe(151.7 ng/m³), Ca(26.2 ng/m³), Ti(5.2 ng/m³), Cd(4.1 ng/m³) were significantly lower than those of 2014(31.4 ng/m³, 242.1 ng/m³, 167.9 ng/m³, 13.0 ng/m³, 8.3 ng/m³, respectively). However, the average concentration of sulfate was 6.3 ug/m³ which was 43% higher than that of 2014 (4.4 ug/m³).

Overall aerosol and its component’s concentrations except for secondary sulfate have been decreased since it was late spring and early summer in Korea during pre-campaign and usually in this season aerosol level is comparatively lower than winter and fall season. And there was only one mild yellow dust episode originated from north china in this period. For the 2016 KORUS-AQ main campaign, it is highly recommended to choose difference time period from pre-campaign in order to investigate the effect of various high PM episodes.