Chlordane enantiomers and temporal trends of chlordane isomers in arctic air.
A 14-year data set (1984-1998) for chlordane compounds in arctic airwas examined to discern temporal trends. trans-Chlordane (TC), cis-chlordane (CC), and trans-nonachlor (TN) declined significantly (p < 0.001-0.02), with apparent times for 50% reduction of 4.9-9.7 y. The isomer fraction of TC = (TC/(TC + CC) also declined significantly (p < 0.001 -0.014) over the same time period. The enantiomeric composition of TC and CC was determined in air samples collected at arctic stations in Canada (1993-1996), Russia (1994), and Finland (1998), and a temperate station on the Swedish west coast (1998). Enantiomer fractions, EF = (+)/[(+) + (-)], were significantly different from measured EFs of racemic standards (0.498-0.501) at all stations for TC (p < 0.001) and two stations for CC (p < 0.001 to <0.05). These observations suggest changing source composition of chlordane in arctic air, with a greater proportion of weathered residues in recent years, possibly derived from soils. Identification of nonracemic (mean EFs = 0.662-0.703) heptachlor exo-epoxide (HEPX) at the four air stations further exemplifies contributions of soil emissions to long-range transport of chlordane-related compounds.
Bidleman
Terry F
TF
Meteorological Service of Canada, Downsview, Ontario. terry.bidleman@ec.gc.ca
Jantunen
Liisa M M
LM
Helm
Paul A
PA
Brorström-Lundén
Eva
E
Juntto
Sirkka
S
D000393:Air Pollutants / Q000032:analysis*; D001110:Arctic Regions; D002706:Chlordan / Q000032:analysis* / Q000737:chemistry*; D004784:Environmental Monitoring; D007306:Insecticides / Q000032:analysis* / Q000737:chemistry*; D007536:Isomerism; D012189:Retrospective Studies
D000393:Air Pollutants; D007306:Insecticides; D002706:Chlordan