Long-range transport and global fractionation of POPs: insights from multimedia modeling studies.
The long-range transport of persistent organic pollutants (POPs) is investigated with two multimedia box models of the global system. ChemRange is a purely evaluative, one-dimensional steady-state (level III) model; CliMoChem is a two-dimensional model with different temperatures, land/water ratios and vegetation types in different latitudinal zones. Model results are presented for three case studies: (i) the effect of atmospheric aerosol particles on the long-range transport of POPs, (ii) the effect of oceanic deposition on the long-range transport of different PCB congeners, (iii) the global fractionation of different PCB congeners. The model results for these case studies show: (i) the low atmospheric half-lives estimated for several organochlorine pesticides are likely to be inconsistent with the observed long-range transport of these compounds; (ii) export to the deep sea reduces the potential for long-range transport of highly hydrophobic compounds (but does not remove these chemicals from the biosphere); (iii) there are different meanings of the term global fractionation that refer to different aspects of the fractionation process and need to be distinguished. The case-study results further indicate that the influences of varying environmental conditions on the physicochemical properties and the degradation rate constants of POPs need to be determined.
Scheringer
M
M
Institute for Chemical and Bioengineering, Swiss Federal Institute of Technology Zürich, CH-8093, Zürich, Switzerland. scheringer@tech.chem.ethz.ch
Salzmann
M
M
Stroebe
M
M
Wegmann
F
F
Fenner
K
K
Hungerbühler
K
K
D000392:Air Movements; D001673:Biodegradation, Environmental; D005591:Chemical Fractionation; D004784:Environmental Monitoring; D004785:Environmental Pollutants; D008962:Models, Theoretical; D011078:Polychlorinated Biphenyls; D013997:Time Factors; D014872:Water Movements
D004785:Environmental Pollutants; D011078:Polychlorinated Biphenyls