α-HCH enantiomer fraction (EF): A novel approach to calculate the ventilation age of water in the Arctic Ocean?

Abstract

α-HCH (hexachlorocyclohexane) and the enantiomeric fraction (EF) of its mirror-image isomers have been determined for water column profiles in the southern Beaufort Sea in 2004 and 2007. Using estimated rates of metabolic degradation, we have applied a simple kinetic model to convert the observed EFs to apparent ventilation ages of the water masses in the study region. We found an age of 1.7 ± 0.1 years for the Polar Mixed Layer (PML), 6.6 ± 0.6 for the core of the Pacific Layer centered at salinity 33.1, and 21.7 ± 0.5 years for the core of the Atlantic Layer identified by a Tmax of ∼0.5°C. These ages are in reasonable accord with other methods used to date water masses in the Arctic Ocean suggesting that α-HCH has an unexploited potential as a dating tool. © 2012. American Geophysical Union. All Rights Reserved.