Thulium (Tm)

Atomic number:	69
Atomic weight:	168.9342
Average concentration in ocean:	1.2 pmol/kg
Residence time:	5,000 years

Distribution in ocean
Tm has a modified, nutrient-like profile similar to that of copper. Concentrations are low at the surface and increase with depth nearly continuously (data).

Speciation
The rare earth elements are present in seawater in the +III oxidation state, except Ce, which can also be oxidized to the +IV state. Complexation with carbonate ion dominates the speciation of REE's, e.g., LaCO₃⁺.

Residence time
The thulium 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.

Analysis
Rare earth elements are determined by mass spectrometry. The measurements shown here were determined using Inductively Coupled Plasms-Mass Spectrometry in shore based laboratories.

References