A noble gas radionuclide analysis of perennially ice covered West Lake Bonney was performed
in order to determine water residence time and ice cover timing. Bulk gas samples were
collected at four depths in the lake. Krypton and argon gases were selectively isolated from the
bulk gas and measurements of 81Kr, 85Kr and 39Ar were made. Radiokrypton and radioargon
analyses yielded lower limit ages of 78 to 285 years, significantly younger than expected based
on previous dating efforts. It was determined that these new data do not invalidate previous
work, but instead offer new insight into the timing of the most recent episode of direct
communication between the atmosphere and West Lake Bonney waters.