 |
| Titel |
Annual cycles of organochlorine pesticide enantiomers in Arctic air suggest changing sources and pathways |
| VerfasserIn |
T. F. Bidleman, L. M. Jantunen, H. Hung, J. Ma, G. A. Stern, B. Rosenberg, J. Racine |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 3 ; Nr. 15, no. 3 (2015-02-09), S.1411-1420 |
| Datensatznummer |
250119398
|
| Publikation (Nr.) |
 copernicus.org/acp-15-1411-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
| Air samples collected during 1994–2000 at the Canadian Arctic air
monitoring station Alert (82°30' N, 62°20' W) were analysed by enantiospecific gas chromatography–mass
spectrometry for α-hexachlorocyclohexane (α-HCH),
trans-chlordane (TC) and cis-chlordane (CC). Results were expressed as enantiomer
fractions (EF = peak areas of (+)/[(+) + (−)] enantiomers), where
EFs = 0.5, < 0.5 and > 0.5 indicate racemic
composition, and preferential depletion of (+) and (−) enantiomers,
respectively. Long-term average EFs were close to racemic values for α
-HCH (0.504 ± 0.004, n = 197) and CC (0.505 ± 0.004, n = 162), and deviated farther
from racemic for TC (0.470 ± 0.013, n = 165). Digital filtration analysis revealed annual cycles of
lower α-HCH EFs in summer–fall and higher EFs in winter–spring. These cycles
suggest volatilization of partially degraded α-HCH with EF < 0.5 from open water and advection to Alert during the warm season, and
background transport of α-HCH with EF > 0.5 during the
cold season. The contribution of sea-volatilized α-HCH was only
11% at Alert, vs. 32% at Resolute Bay (74.68° N,
94.90° W) in 1999. EFs of TC also followed annual cycles of lower
and higher values in the warm and cold seasons. These were in phase with low
and high cycles of the TC/CC ratio (expressed as FTC = TC/(TC+CC)),
which suggests greater contribution of microbially "weathered" TC in
summer–fall versus winter–spring. CC was closer to racemic than TC and
displayed seasonal cycles only in 1997–1998. EF profiles are likely to
change with rising contribution of secondary emission sources, weathering of
residues in the environment, and loss of ice cover in the Arctic.
Enantiomer-specific analysis could provide added forensic capability to air
monitoring programs. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|