Modelling the Atmospheric Transport and Environmental Fate of Persistent Organic Pollutants in the Northern Hemisphere using a 3-D Dynamical Model

Abstract

Persistent organic pollutants (POPs) are a group of chemical compounds with mainly anthropogenic origin; they are semi-volatile, hydrophobic, they bioaccumulate, they have toxic effects on human and wildlife and they display low degradation rates in the environment (Jones and de Voogt, 1999). POPs are emitted to the atmosphere either from industrial production, as by-products from combustion, or intentionally as pesticides used on crops or for insect control. A number of POPs are banned or subject to regulation, e.g. under the UNEP Stockholm convention for POPs and emissions of them have decreased during the last decades (Jones and de Voogt, 1999). However, due to the great persistence large amounts are still cycling in the environment. The volatility of POPs is temperature dependent, which can lead to several consecutive deposition and re-emission events named multi-hop or grasshopper transport (Wania and Mackay, 1996). To contribute to the understanding of these processes several models are developed. The environmental fate of POPs is traditionally studied with box models (e.g. Wania et al., 1999). Recently, atmospheric transport models with high spatiotemporal resolution are also developed to address these issues (e.g. Koziol and Pudykiewicz, 2001; Hansen et al., 2004). The latest development of the Danish Eulerian Hemispheric Model (DEHM) at the National Environmental Research Institute now includes a description of the air-surface gas-exchange processes of soil, water and snow to study the environmental fate of POPs. The original version of the DEHM model was developed for studying the long-range transport of SO2 and SO4 to the Arctic (Christensen, 1997).