Cadmium (Cd)

Atomic number: 48
Atomic weight: 112.41
Average concentration in ocean: 620 pmol/kg
Residence time: 50,000 years

Distribution in ocean
Cd has a nutrient-like vertical profile.  Concentrations are depleted at the surface and concentrations increase with depth (data).  Cd is highly correlated with dissolved PO43-. 

Speciation
Dissolved Cd is present in seawater in the +II oxidation state as the CdCl+ ion.

Residence time
The cadmium residence  was calculated from the global average river input (Bruland, 1980).

Analysis
Cadmium is determined by graphite furnace atomic absorption spectrophotometry after sample preconcentration with an organic extraction.

References