Cesium (Cs)

Atomic number: 55
Atomic weight: 132.9054
Average concentration in ocean: 2.3 nmol/kg
Residence time: 330,000 years

Distribution in ocean
Cesium has a conservative distribution in the ocean.  The concentration is relatively constant vertically and horizontally (data).

Cesium exists in seawater as the Cs+ ion.

Residence time
The cesium residence time is from Tracers in the Sea (Broecker, W. S. and Peng, T.-H., 1982.  Eldigo Press, Palisades, NY).  It was calculated from the global average river input.

Cesium can be determined by neutron activation analysis, atomic absorption spectrometry or mass spectrometry.