The international polar year (IPY) circumpolar flaw lead (CFL) system study: The importance of brine processes for α‐ and γ‐hexachlorocyclohexane (HCH) accumulation or rejection in sea ice

We present evidence that both geophysical and thermodynamic conditions in sea ice are important in understanding pathways of accumulation or rejection of hexachlorocyclohexanes (HCHs). α‐ and γ‐HCH concentrations and α‐HCH enantiomer fractions have been measured in various ice classes and ages from the Canadian High Arctic. Mean α‐HCH concentrations reached 0.642 ± 0.046 ng L–1 in new and young ice ( 200 cm). Mean γ‐HCH concentrations were 0.066 ± 0.006 ng L–1 in new and young ice, 0.040 ±0.002 ng L–1 in the first‐year ice and 0.040 ±0.007 ng L–1 in the old ice. In general, α‐HCH concentrations and vertical distributions were highly dependent on the initial entrapment of brine and the subsequent desalination process. γ‐HCH levels and distribution in sea ice were not as clearly related to ice formation processes. During the year, first‐year ice progressed from freezing (accumulation) to melting (ablatio...