Sources and Pathways 4.1
Chapter 4 Persistant toxic substances (PTS) sources and pathways 4.1. Introduction Chapter 4 4.1. Introduction 4.2. Assessment of distant sources: In general, the human environment is a combination Longrange atmospheric transport of the physical, chemical, biological, social and cultur- Due to the nature of atmospheric circulation, emission al factors that affect human health. It should be recog- sources located within the Northern Hemisphere, par- nized that exposure of humans to PTS can, to certain ticularly those in Europe and Asia, play a dominant extent, be dependant on each of these factors. The pre- role in the contamination of the Arctic. Given the spa- cise role differs depending on the contaminant con- tial distribution of PTS emission sources, and their cerned, however, with respect to human intake, the potential for ‘global’ transport, evaluation of long- chain consisting of ‘source – pathway – biological avail- range atmospheric transport of PTS to the Arctic ability’ applies to all contaminants. Leaving aside the region necessarily involves modeling on the hemi- biological aspect of the problem, this chapter focuses spheric/global scale using a multi-compartment on PTS sources, and their physical transport pathways. approach. To meet these requirements, appropriate modeling tools have been developed. Contaminant sources can be provisionally separated into three categories: Extensive efforts were made in the collection and • Distant sources: Located far from receptor sites in preparation of input data for modeling. This included the Arctic. Contaminants can reach receptor areas the required meteorological and geophysical informa- via air currents, riverine flow, and ocean currents. tion, and data on the physical and chemical properties During their transport, contaminants are affected by of both the selected substances and of their emissions.
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