Atomic number: | 77 |
Atomic weight: | 192.22 |
Average concentration in ocean: | 680 amol/kg |
Residence time: | 2000 to 20,000 years |
Speciation
Iridium probably exists in the +III
oxidation state as chloro- or hydroxy- complexes.
Residence time
The upper limit on the iridium residence time was determined from the global
average river input and the lower limit from the rate of removal to sediments (Anbar
et al., 1996).
Analysis
Iridium is determined by isotope
dilution using thermal ionization, mass spectrometry after concentration with
anion exchange resins.