Atmospheric deposition of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in urban and suburban areas of Korea

Bulk atmospheric samples (wet and dry) were collected monthly throughout a year at urban and suburban areas of Korea to assess the deposition flux and seasonal variations of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs). The PCDDs/DFs deposition fluxes ranged from 1.0 to 3.7 ng TEQ/m2/year in the urban area and from 0.5 to 4.6 ng TEQ/m2/year in the suburban area. The deposition fluxes of PCDDs/DFs in this study were comparable to or lower than those previously reported at different locations. The atmospheric deposition fluxes of particles and PCDDs/DFs in winter tended to be higher than those in summer. However, monthly variations between particle and PCDDs/DFs deposition fluxes were small, and the correlation coefficients between the deposition fluxes of air particles and each homologue group of PCDDs/DFs varied according to the degree of chlorination of the homologue group. The deposition velocity of PCDDs/DFs in the urban area was estimated at 0.04 cm/s, which is a lower value than those found in other studies. The two most likely factors affecting the monthly variation of deposition fluxes are the ambient temperature and the amount of precipitation. In particular, the ambient temperature had an influence on the lower chlorinated homologues of PCDDs/DFs while precipitation had an influence on the higher chlorinated PCDDs/DFs. The PCDDs/DFs profiles in atmospheric deposition bulk samples showed a similar pattern at the urban and suburban sites. The possibility of the loading of PCDDs/DFs by Asian dust events could be partly confirmed by investigation of homologue profiles.