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Second AMAP International Symposium on Environmental Pollution of the Arctic. Rovaniemi, 1-4 October 2002
Evidence for “Recycled” POPs in the Arctic Atmosphere Terry Bidleman1, Liisa Jantunen1, Paul Helm2, Eva Brorström-Lundén3, Sirkka Juntto4, Anders Södergren5, Cecilia Backe 5 1
Meteorological Service of Canada, Downsview, ON, Canada; 2Dept. of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada; 3Swedish Environmental Research Institute, Gothenburg, Sweden; 4Finnish Meteorological Institute, Helsinki, Finland; 5 Dept. of Chemical Ecology and Ecotoxicology, Lund University, Lund, Sweden. Introduction Twelve persistent organic pollutants (POPs) are scheduled to be eliminated from worldwide production and use under the UNEP Protocol and other POPs have already been banned or controlled under regional initiatives such as UN-ECE-LRTAP. As their usage dwindles, re-emission of “legacy” POPs from soil and water will become increasingly more important in buffering atmospheric concentrations. Air monitoring programs designed to verify the effectiveness of these protocols will need to consider the contributions from “old” sources, as well as fresh releases, in the interpretation of long-term trends in atmospheric concentrations. Here we show how chemical markers can be used to infer sources and pathways of the pesticides chlordane, α-hexachlorocyclohexane (α-HCH), and toxaphene. Methods Air samples from monitoring stations at Alert, Canada (1993-96) and Dunai, Russia (1993-94) were obtained from the extract archive at Meteorological Service of Canada. The Swedish Environmental Research Institute supplied 1998 air samples from monitoring stations at Pallas, Finland and Rörvik on the Swedish west coast. Locations are shown in Bidleman et al. (2002a). Historical (1971-73) atmospheric deposition samples from southern Sweden were collected on silicone-oil coated nets as described by Södergren (1972). Air samples from the southern U.S. were collected in 1996-97 using published methods (Jantunen et al., 2000). Samples were extracted, cleaned up and analysed as previously described (Bidleman et al., 2002a; Jantunen and Bidleman, 1996; Jantunen et al., 2000; Södergren,1972). Analysis was carried out by gas chromatography - negative ion mass spectrometry (GC-NIMS) using a 60-m DB-5 column for toxaphene and chiral cyclodextrin-phase columns for pesticide enantiomers. Results and Discussion Chlordane enantiomers Chlordane was used in the U.S. for agriculture, home lawns and gardens and as a termiticide until the mid-1980s when it was restricted to termiticide applications only. It was deregistered in the U.S. in 1988 and voluntarily withdrawn from the world market in 1997. The enantiomer fractions, EF = (+)/[(+) + (-)], of chlordanes vary with source type; see Bidleman et al., 2002b for review. Transchlordane (TC) and cis-chlordane (CC) are racemic (EF = 0.500) in technical chlordane, soils near house foundations treated for termite control, and indoor air. Agricultural soils generally show preferential depletion of (+)TC (EF 0.500). Chlordanes in ambient air are non-racemic in the Great Lakes region and closer to racemic in the southern U.S. These regional differences may reflect greater relative contribution from soils in the Great Lakes states vs. termiticide sources in the southern U.S. Concentrations of chlordane isomers in arctic air declined between 1984-98 with times for 50% reduction of 4.9–9.7 y (Bidleman et al., 2002a; Hung et al., 2002). The isomer fraction, TC/(TC+CC), also declined over the same time period (Bidleman et al., 2002a). TC is more labile in the environment
P – P01
Second AMAP International Symposium on Environmental Pollution of the Arctic. Rovaniemi, 1-4 October 2002
and sources of chlordane to the Arctic may have gradually shifted from fresh usage to older residues, perhaps “recycled” from soils. This hypothesis is supported by occurrence of non-racemic chlordanes in arctic air between 1993-98 (Figure 1) (Bidleman et al., 2002a). Mean EFs of TC (0.463-0.477) at the three arctic stations (Alert, Dunai and Pallas) and the temperate station (Rörvik) indicated statistically significant (p
