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| Titel |
Fractionation and current time trends of PCB congeners: evolvement of distributions 1950–2010 studied using a global atmosphere-ocean general circulation model |
| VerfasserIn |
G. Lämmel, I. Stemmler |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 12, no. 15 ; Nr. 12, no. 15 (2012-08-07), S.7199-7213 |
| Datensatznummer |
250011378
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| Publikation (Nr.) |
 copernicus.org/acp-12-7199-2012.pdf |
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| Zusammenfassung |
PCBs are ubiquitous environmental pollutants expected to decline in abiotic
environmental media in response to decreasing primary emissions since the
1970s. A coupled atmosphere-ocean general circulation model with embedded
dynamic sub-models for atmospheric aerosols and the marine biogeochemistry
and air-surface exchange processes with soils, vegetation and the cryosphere
is used to study the transport and fate of four PCB congeners covering a
range of 3–7 chlorine atoms.
The change of the geographic distribution of the PCB mixture reflects the
sources and sinks' evolvement over time. Globally, secondary emissions
(re-volatilisation from surfaces) are on the long term increasingly gaining
importance over primary emissions. Secondary emissions are most important
for the congeners with 5–6 chlorine atoms. Correspondingly, the levels of
these congeners are predicted to decrease slowest. Changes in congener
mixture composition (fractionation) are characterized both geographically
and temporally. In high latitudes enrichment of the lighter, less persistent
congeners and more delayed decreasing levels in response to decreasing
emissions are found. The delivery of the contaminants to high latitudes is
predicted to be more efficient than previously suggested. The results
suggest furthermore that the effectiveness of emission control measures may
significantly vary among substances. The trends of decline of organic
contaminant levels in the abiotic environmental media do not only vary with
latitude (slow in high latitudes), but do also show longitudinal gradients. |
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