Ultra-sensitive mass spectrometric and other methods applied to environmental problems

Summary

¹³⁷Cs concentrations in seawater collected in 2002 and archived samples collected in 1957 were determined by using an AMP precipitation method and γ -spectrometry. ¹³⁷Cs concentrations in the present water columns (>0.2 Bq ^. m^-3) were determined using sample volumes of around 10 liters by the AMP precipitation method and ground-level γ-spectrometry at the Meteorological Research Institute (MRI). Equipment at the Ogoya Underground Laboratory (OUL) is able to achieve very low radioactivity measurements. As a result, we were able to measure ¹³⁷Cs concentrations in deep waters (100-1500 m) in 1957, of about 1 Bq ^. m^-3 from a small volume (250 ml) of the archived samples. The high sensitive ¹³⁷Cs measurements allow effectively using ¹³⁷Cs as a tracer of water motion in the ocean.