Concentrations of
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- and
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-hexachlorocyclohexane (HCH)were measured in ambient air samples on a weekly basisbetween 1991 and 1995 at Lista, a coastal station insouthern Norway. The levels averaged at 66 pg/m
3![](/images/gifchars/alpha.gif)
-HCHand 48 pg/m
3 ![](/images/gifchars/gamma.gif)
-HCH. A 50% decline of
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-HCHconcentrations in air could be observed during the 5 year period,while no such trend was found for
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-HCH. The timeprofileof concentrations in air was characterized by a generallylow base line level with a few spring-time episodes ofhighly elevated concentrations. Under this pattern ofepisodicconcentration spikes lies a background with seasonallyvariable
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-HCH levels, showing higher concentrations athigher temperatures.
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-HCH concentrations in airarefar less temperature sensitive. Episodes with airconcentrations of
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-HCH up to 1000 pg/m
3 coincided with airtransportfrom Western Central Europe, whereas episodes withelevated
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-HCH levels up to 300 pg/m
3 tended tocorrelatewith air transport from easterly directions, but did nolonger occur in 1994 and 1995. This is in agreementwiththe usage pattern of HCH pesticides in different regionsof Europe and points toward regional atmospheric transportas the major source of these chemicals, especially
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-HCH.Short episodes of elevated concentrations proved tobevery important when trying to quantify the atmosphericinputof
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-HCH into southern Norway, whereas
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-HCH levelsare more strongly influenced by the global backgroundsituation. Air concentrations and
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/
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concentrationratioswere clearly correlated with air massorigin.