Title Atmospheric transport of persistent semi-volatile organic chemicals to the Arctic and cold condensation in the mid-troposphere; Part 1, 2-D modeling in mean atmosphere
Author Ma, J.
Author Affil Ma, J., Environment Canada, Air Quality Research Division, Toronto, ON, Canada
Source Atmospheric Chemistry and Physics, 10(15), p.7303-7314, . Publisher: Copernicus, Katlenburg-Lindau, International. ISSN: 1680- 7316
Publication Date 2010
Notes In English. Published in Atmospheric Chemistry and Physics Discussions: 12 January 2010, http://www.atmos-chem-phys- discuss.net/10/453/2010/acpd-10-453-2010.html ; accessed in June, 2011. 58 refs. GeoRef Acc. No: 310030
Index Terms atmospheric circulation; condensation; convection; liquid phases; pollution; soil pollution; soils; soil temperature; solid phases; solubility; statistical analysis; temperature; velocity; volume; wind velocity; Arctic region; activation energy; air pollution; atmosphere; atmospheric transport; chlorinated hydrocarbons; equatorial region; gaseous phase; halogenated hydrocarbons; Henry's law; hexachlorocyclohexane; insecticides; liquid phase; low temperature; organic compounds; organochlorine pesticides; pesticides; pollutants; semivolatile organic compounds; solid phase; time series analysis; transport; troposphere; two-dimensional models; volatiles; winds
Abstract In the first part of this study for revisiting the cold condensation effect on global distribution of semi-volatile organic chemicals (SVOCs), the atmospheric transport of SVOCs to the Arctic in the mid-troposphere in a mean meridional atmospheric circulation over the Northern Hemisphere was simulated by a two-dimensional (2-D) atmospheric transport model. Results show that under the mean meridional atmospheric circulation the long- range atmospheric transport of SVOCs from warm latitudes to the Arctic occurs primarily in the mid-troposphere. Although major sources are in low and mid-latitude soils, the modeled air concentration of SVOCs in the mid-troposphere is of the same order as or higher than that near the surface, demonstrating that the mid-troposphere is an important pathway and reservoir of SVOCs. The cold condensation of the chemicals is also likely to take place in the mid-troposphere over a source region of SVOCs in warm low latitudes through interacting with clouds. We demonstrate that the temperature dependent vapour pressure and atmospheric degradation rate of SVOCs exhibit similarities between lower atmosphere over the Arctic and the mid- troposphere over a tropical region. Frequent occurrence of atmospheric ascending motion and convection over warm latitudes carry the chemicals to a higher altitude where some of these chemicals may partition onto solid or aqueous phase through interaction with atmospheric aerosols, cloud water droplets and ice particles, and become more persistent at lower temperatures. Stronger winds in the mid-troposphere then convey solid and aqueous phase chemicals to the Arctic where they sink by large-scale descending motion and wet deposition. Using calculated water droplet- air partitioning coefficient of several persistent organic semi-volatile chemicals under a mean air temperature profile from the equator to the North Pole we propose that clouds are likely important sorbing media for SVOCs and pathway of the cold condensation effect and poleward atmospheric transport. The role of deposition and atmospheric descending motion in the cold condensation effect over the Arctic is also discussed.
URL http://www.atmos-chem-phys.net/10/7303/2010/acp-10-7303-2010.pdf
Publication Type journal article
Record ID 65006822