Changing the cadmium : phosphorus paradigm?

The well-established strong linear relationship linking dissolved cadmium (Cd) and phosphorus (P) concentrations in seawater is at the origin of the attraction of Cd as a proxy for PO4 in the paleocean. However, exploring the dissolved Cd and PO4 distributions in the ocean, Quay and co-workers (2015, see reference below) show that the Cd/P of particles exported from the surface ocean doubles in high-nutrients low chlorophyll (HNLC) regions. They also demonstrate that Cd/PO4 variations in the surface ocean and deep sea depend on Cd/P of degraded particles. Using a box model, they present evidence that past changes in HNLC conditions would change the Cd-PO4 relationship in deep sea… which has to be considered in paleo-reconstructions!

15 2 Quay
Figure: The meridional and interbasin trends in the estimated Cd/P ratio of particles exported from the surface ocean. The Cd/P of exported particles is a primary factor controlling the spatial variations dissolved Cd/P in the surface ocean and in the deep sea where particles are degraded.

Reference:

Quay, P., Cullen, J., Landing, W., & Morton, P. (2015). Processes controlling the distributions of Cd and PO4 in the ocean. Global Biogeochemical Cycles, 29(6), 830–841. doi:10.1002/2014GB004998

Latest highlights

Lead isotopes allow tracing the processes injecting of anthropogenic lead in deep waters

This work follows the penetration of anthropogenic lead (traced using its isotopic signatures) into the pristine deep Pacific Ocean.

Challenging results on iron bioavailability in the Southern Ocean

Fourquez and co-authors conducted dissolved iron uptake experiments with Phaeocystis antarctica…

Protactinium-231 budget of the Atlantic sector of Southern Ocean

Levier and colleagues analysed dissolved and particulate protactinium-231 in samples collected in a section in the Southern Ocean…

Using machine learning to accurately simulate the oceanic barium distribution

Mete and colleagues used machine learning to predict the global distribution of oceanic barium…

Rechercher