Airborne cadmium in spring season between Asian dust and non-Asian dust periods in Korea

In an effort to elucidate the environmental significance of the long-range transport of atmospheric pollutants (LRTAP), the particle-bound Cd data for an aerodynamic diameter less than 2.5 (PM2.5) and 10 μm (PM10) fractions were analyzed in the spring periods of four consecutive years between 2001 and 2004. To describe the factors affecting Cd distributions in relation to LRTAP, the Cd measurement data were evaluated after being grouped into several criteria: Asian dust (AD)/non-Asian dust (NAD), particle size, metal specie, source location, etc. According to our analysis, Cd concentrations in the coarse fraction were higher during AD (2.21±1.88 ng m−3) than during NAD (1.58±1.11 ng m−3). In contrast, its fine-fraction counterpart showed a contrary pattern with more enhanced values during NAD (2.60±1.64 ng m−3) than AD (1.60±0.65 ng m−3). Evidence collected from the present study indicates that the occurrence of the AD events generally proceed with the inflow of Cd-deficient particle, as reflected by a persistently low Cd/PM ratio from all particle fractions. Inspection of the Cd data in relation with the back trajectory analysis further suggests that the AD event is not the main route of the Cd transport into Korea, although such mechanism can be efficient depending on such variables as the size of particle as well as the intensity and transport route of AD.