Multi-year observations of organohalogen pesticides in the Arctic atmosphere C.J. Halsall a, *, R. Bailey a , G.A. Stern b , L.A. Barrie a , P. Fellin c , D.C.G. Muir d , B. Rosenberg b , F. Ya. Rovinsky e , E. Ya. Kononov e , B. Pastukhov e a Atmospheric Environment Service, 4905 Duerin St, Downsview, Ontario, Canada M3H 5T4 b Freshwater Institute, 501 University Crescent, Winnipeg, Manitoba, Canada R3T 2N6 c Conor Paci®c, 2 Tippett Road, Toronto, Ontario, Canada M3H 2V2 d National Water Research Institute, 867 Lakeshore Rd, Burlington, Ontario, Canada L7R 4A6 e Institute of Global Climate and Ecology, 20-b Glebovskaya St, 107258 Moscow, Russia Received 19 January 1998; revised 24 February 1998; accepted 24 March 1998 Abstract Atmospheric measurements of organohalogen pesticides (OCs) have been made in both the Canadian and Russian Arctic. A full quality-controlled database of weekly samples is now available for the years 1992±94. Hexachlorobenzene (HCB) and the hexa- chlorocyclohexanes (HCHs) were the most predominant compounds in the atmosphere, followed by the chlordanes and endosulfan. Evidence of a seasonality in air concentrations was apparent particularly for the pesticide metabolites, compounds such as oxy- chlordane, heptachlor epoxide and dieldrin showing a signi®cant positive correlation with temperature ( p<0.01). An exception to this was p, p 0 -DDE which showed elevated levels during the winter. Large spatial dierences in mean annual concentrations of most OCs were not evident; however, spatial dierences were apparent in a/g-HCH ratios between the high Arctic site of Alert and the Yukon site of Tagish. The in¯uence of both the European sector and the regional eect of the Arctic Ocean on the high Arctic probably accounted for this dierence. A decline in the trans-chlordane/cis-chlordane ratio compared to studies during the 1980s may indicate a more weathered source of chlordane to be present in the Arctic by the mid-1990s. Slopes generated from plots of partial pressure (ln P) versus 1/T for selected compounds were considerably less steep than those derived from temperate studies. It is inferred here that long-range transport has a large in¯uence on contaminant levels in the arctic atmosphere. # 1998 Elsevier Science Ltd. All rights reserved. Keywords: Artic atmosphere; Pesticides; POPs; Long-range transport 1. Introduction Over the last two decades concern has grown about anthropogenic pollutants contaminating the arctic environment. Persistent organic pollutants (POPs) such as the organochlorine pesticides (OCs) have now been widely detected in both abiotic and biotic matrices within the arctic region, with concern focused on the indigenous arctic peoples (CACAR, 1997; DeMarch et al., 1998). Indeed, recent modelling eorts have pre- dicted an accumulation of many semi-volatile organic compounds (SOCs) in the polar regions (Wania and Mackay, 1996), the atmosphere being key to the movement of POPs from southerly source regions (Harner, 1997). Organohalogen pesticides as a chemical group cover a wide range of physical±chemical properties. Their usage on a global scale has varied tremendously, and while some of them have been banned/restricted in western/ industrialised countries, i.e. 1,1,1-tri-chloro-2,2-bis(p- chlorophenyl)ethane (DDT), toxaphene, chlordane (Barrie et al., 1992), their use prevails in other parts of the globe. For instance, DDT and hexachloro- cyclohexane (HCH) are still produced and used within India (Nair and Pillai, 1992). For industrialised coun- tries lindane (g-HCH), endosulfan and tri¯uralin are examples of current-use pesticides applied both in Europe and North America (Ho et al., 1992a; Li et al., 1996; Key et al., 1997). Their persistence in the envir- 0269-7491/98/$19.00 # 1998 Elsevier Science Ltd. All rights reserved. PII: S0269-7491(98)00074-8 ENVIRONMENTAL POLLUTION Environmental Pollution 102 (1998) 51±62 * Corresponding author. Institute of Environmental & Natural Sciences, Lancaster University, Lancaster LA1 4YQ, UK. Fax: +44- 1524-593985; e-mail: c.halsall@lancaster.ac.uk