On the global distribution of persistent organic pollutants

The global distribution of persistent organic pollutants (POPs) has become one of the main environmental problems in the last decade. This article gives an overview of the main contributions to the knowledge of the atmospheric transport and accumulation mechanisms of POPs in remote areas, based on their analysis in selected environmental compartments from high altitude mountain regions of Europe. The studies indicated that transport and deposition of polycyclic aromatic hydrocarbons are mainly linked to atmospheric particles. Consequently, wet and dry deposition are the main removal processes of these compounds from the atmosphere, resulting in a significant influence of regional sources. In contrast, gas exchange seems to be the main input mechanism of organochlorine compounds (OCs) from the atmosphere to terrestrial and aquatic systems. For these compounds, an altitude dependence of their accumulation in fish muscle and sediments was detected, with a major retention of the less volatile compounds (vapor pressure less than or equal to 10(-2.5) Pa) in the locations situated at higher altitude, those of lower annual average temperature, whereas no relationship was observed for more volatile OCs. The results represent a new aspect in the Global Distillation Effect theory as proposed for semivolatile persistent pollutants, indicating that this transport mechanism not only involves transfer from low to high latitudes, but also preferential accumulation of the less volatile compounds in high altitude regions of mid-latitude areas.