32Si in precipitation: evaluation of temporal and spatial variation and as dating tool for glacial ice

The use of32Si (half-life about 140 yr) as a dating tool requires knowledge of its temporal and spatial distribution. Previously reported and new data are similar to the patterns of other cosmogenic radionuclides: latitude and seasonal variation, anti-correlation to solar activity, contribution from nuclear weapons testing, highest natural concentrations in Antarctica. Compiled and estimated32Si/Si ratios show that rain, snow and ice samples of low Si concentration could be measured by accelerator mass spectrometry. A significant single-event32Si deposition (concentration higher by a factor of 4) was detected (β counting) in fresh snow on the Jungfraujoch, Switzerland, due to scavenging from the atmosphere by an abnormally high atmospheric dust content.