Evidence for the "grasshopper" effect and fractionation during long-range atmospheric transport of organic contaminants.
Although there is indisputable evidence that long-range atmospheric transport (LRAT) of organic contaminants occurs on a global scale, uncertainties remain about the detailed mechanism and extent of this phenomenon as well as the physical-chemical properties which facilitate LRAT. In this study, we discuss how mass balance models and monitoring data can contribute to a fuller understanding of the mechanism and extent of LRAT. Specifically we address the issues of "grasshopping" or "hopping" (the extent to which molecules are subject to multiple hops as distinct from a single emission-deposition event) and "global fractionation" (the differing behavior of chemicals as they are transported). It is shown that simple mass balance models can be used to assist the interpretation of monitoring data while also providing an instrument that can be used to assess the LRAT potential and the extent of hopping that organic substances may experience. The available evidence supports the notion that many persistent organic pollutants experience varying degrees of "hopping" during their environmental journey and as a consequence become fractionated with distance from source.
Gouin
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Canadian Environmental Modelling Centre, Trent University, Peterborough, Ontario, Canada K9J 7B8. tgouin@trentu.ca
Mackay
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Jones
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KC
Harner
T
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Meijer
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SN
D000392:Air Movements; D000393:Air Pollutants / Q000737:chemistry*; D000397:Air Pollution; D005591:Chemical Fractionation; D004784:Environmental Monitoring / Q000706:statistics & numerical data*; D006581:Hexachlorobenzene / Q000737:chemistry; D008962:Models, Theoretical; D009010:Monte Carlo Method; D009930:Organic Chemicals / Q000737:chemistry*; D011078:Polychlorinated Biphenyls / Q000737:chemistry
D000393:Air Pollutants; D009930:Organic Chemicals; D006581:Hexachlorobenzene; D011078:Polychlorinated Biphenyls; C014024:2,4,5,2',4',5'-hexachlorobiphenyl