Chlordane Enantiomers and Temporal Trends of Chlordane Isomers in Arctic Air

Abstract

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.

Comparing measured and predicted PCB concentrations in Arctic seawater and marine biota

“…The difference between predicted and measured dissolved PCB water concentration is much larger (100 times) than the annual change in dissolved water concentrations (2 times) reported from other Arctic ice covered marine areas (Hargrave et al, 1997(Hargrave et al, , 2000Fisk et al, 2001b). Although contaminants in the Arctic have decreased in the last decades, such as in air (Bidleman et al, 2002), there was in general no decrease in the 1990s in PCB air concentrations neither in the Svalbard area nor the Canadian Arctic (Hung et al, 2001;Berg et al, 2003). Thus, the large difference between reported (or predicted) water concentration from 1996 and 1999 cannot be due to temporal decrease in ambient PCB concentration.…”

Enantiomer Fractions of Organic Chlorinated Pesticides in Arctic Marine Ice Fauna, Zooplankton, and Benthos

“…A part of the EOM-free extracts were shipped to the Meteorological Service of Canada, Toronto, Canada, for analysis of the enantiomer composition of chiral CPs. Enantiomer determinations were done by capillary gas chromatographyelectron capture negative ion mass spectrometry using published conditions (14,(36)(37)(38) or slight variations. Two ions were monitored for each compound, R-HCH 255/257, chlordanes 410/412, and o,p′-DDT 246/248.…”

Organochlorine pesticides in seawater and the surrounding atmosphere of the marginal seas of China: Spatial distribution, sources and air–water exchange

“…TC is more susceptible to photo-degradation than CC in the environment (Hung et al, 2005). In general, the technical mixture TC/CC ratio has been reported to be approximately 1.1, and a ratio less than 1.1 indicates a more aged source (Bidleman et al, 2002;Hung et al, 2005). The ratios of TC/CC ranged from 0.6 to 1.0 (0.80±0.15) in the air and indicated that a great change had occurred in the composition with respect to the technical chlordane after long-range atmospheric transport.…”