Modelling the behaviour of PAHs during atmospheric transport from the UK to the Arctic.

Halsall, Crispin J. and Sweetman, Andrew and Barrie, L. A. and Jones, Kevin C. (2001) Modelling the behaviour of PAHs during atmospheric transport from the UK to the Arctic. Atmospheric Environment, 35 (2). pp. 255-267. ISSN 1352-2310

Abstract

Persistent organic pollutants (POPs) such as PAHs are subject to long-range atmospheric transport, which can result in the contamination of remote areas such as the Arctic. A simple model was developed to describe the removal processes of four PAHs; fluorene (FLU), phenanthrene (PHEN), fluoranthene (FLA) and benzo[a]pyrene (B[a]P) transported over a 5 day period from a source area over the UK to the Russian Arctic. The purpose of this model was to study processes affecting the PAHs within the atmosphere, rather than their interaction with the earth's surface. The components to the model included gas/particle partitioning, reaction with OH radicals and dry and wet deposition (both rain and snow). Atmospheric/meteorological parameters for the geographical region of interest were generated from three-dimensional atmospheric models. Air concentrations were prescribed in the source area with no additional PAH inputs along the transect, both winter and summer scenarios were modelled. Reaction with OH was a major removal mechanism for gas-phase FLU, PHEN and FLA, most notably in the temperate atmosphere. Wet deposition in the form of snow accounted for the majority of PAH loss in the winter, although the gas and particle scavenging ratios used in this model ranged over several orders of magnitude. Using a 5 day transport scenario in a `1-hop’ event, the model predicted that a primary emission of FLA and B[a]P to the atmosphere of the southern UK, would not reach the Russian Arctic at a distance of 3500 km, assuming a constant windspeed of 10 m s−1. However, both FLU and PHEN with calculated half-lives of >60 h during the winter could be transported to this area under this scenario.