Cadmium cycle

Dissolved cadmium circulates through freshwater systems before introduction to larger bodies of water.

[1] Cadmium behaves similarly to nutrients such as phosphate and zinc: dissolved concentrations depend heavily on uptake, assimilation, and deposition by phytoplankton and diatoms.

[2] Dissolved cadmium concentrations are sub-nanomolar in the surface ocean and increase with depth, with a maximum in the thermocline.

Higher concentrations (up to 1 nM) occur in the deep Indian, Southern, and Pacific oceans due to water mass aging during thermohaline circulation.

[1] Coastal waters range from 0.2 to 0.9 nM, denoting a significant terrestrial input.