Precipitation scavenging of particle-bound contaminants: A case study of PCDD/Fs
2009 (English)In: Atmospheric Environment, ISSN 1352-2310, Vol. 43, no 38, 6084-6090 p.Article in journal (Other academic) Published
Precipitation scavenging of particles is a major mechanism for atmospheric deposition of organic contaminants, but there have been few field studies. We studied precipitation scavenging of PCDD/Fs with the aim of deepening understanding of environmental variables influencing this process. Bulk deposition of PCDD/Fs and their concentrations in ambient air measured at a background site in Sweden were used to calculate precipitation scavenging ratios. Contrary to expectations, increasing scavenging ratios with decreasing degree of chlorination of the PCDD/F congeners were observed when the particle-associated PCDD/F concentrations in air were used for the calculation. This was attributed to differences in temperature and thereby in the gas - particle partitioning of the PCDD/Fs between ground level and clouds where much of the particle scavenging occurs. When the particle-associated PCDD/F concentrations were recalculated for a 10-20 degrees C lower temperature, the scavenging ratios of the different PCDD/F congeners were similar. Hence differences between ground level and in-cloud temperature should be considered when calculating scavenging ratios from field observations and when modeling this process. The scavenging ratios averaged similar to 200 000, with lower values when the particle-associated PCDD/F concentration in air was lower. The soot concentration in air was a good predictor of bulk deposition of PCDD/Fs.
Place, publisher, year, edition, pages
Elsevier Ltd , 2009. Vol. 43, no 38, 6084-6090 p.
Precipitation scavenging, Scavenging factor, PCDD/F, Soot, Bulk deposition
IdentifiersURN: urn:nbn:se:su:diva-34936DOI: 10.1016/j.atmosenv.2009.08.037ISI: 000272276000011ISBN: 1352-2310OAI: oai:DiVA.org:su-34936DiVA: diva2:286029