Interactions of dissolved CO2 with cadmium isotopes in the Southern Ocean

Abstract

A B S T R A C THere we report the first ever observations of a strong correlation in ocean surface waters of the dissolved δ 114 Cd with dissolved CO 2 . This is observed in the Southern Ocean along the 0°W meridian in both and its conversion to CO 2 . For this the algae need more enzyme carbonic anhydrase that normally has Zn as its co-factor, but Cd may substitute for Zn and there also are Cd-specific carbonic anhydrases known for some phytoplankton species. Indeed in incubations of the local plankton communities it is shown that the phytoplankton have a very strong preferential uptake of CO 2 , such that the uptake ratio { seawater. Future research of local phytoplankton in unperturbed natural waters of the Southern Ocean is recommended to be able to verify the hypothesis of a function of Cd in carbonic anhydrase in Antarctic phytoplankton.

δ114/110Cd Values of a Suite of Different Reference Materials

“…2016, de Baar et al . 2017). Adsorption and precipitation also produce measurable Cd isotope fractionation (Horner et al .…”

Low cerium among the dissolved rare earth elements in the central North Pacific Ocean

“…Surface waters of the Antarctic Ocean comprise ample major nutrients. Quite remarkably dissolved ''nutrient-type" trace metals Zn, Cd, Ni and Cu show the same trend with higher concentrations in Antarctic surface waters (de Baar et al, 2017c; their Table 1). Notably dissolved Zn and Cd are much higher in Antarctic surface waters than in the surface waters of the oligotrophic central North Pacific Ocean, but Ni and Cu are elevated as well when compared with the central North Pacific.…”

“…The Antarctic Ocean shows elevated REE in surface waters, following the trend of elevated major nutrients and trace metals (de Baar et al, 2017c, their Hathorne et al (2015) are all situated south of the APF and in the upper 1000 m of the water column show significantly higher REE concentrations than in the upper 1000 m of their stations 101 and 104 situated north of the APF. Because of these 'High Nutrient' conditions in upper waters of the Antarctic Ocean, the Antarctic relationships of the trivalent REE with the major nutrients are not necessarily suitable for comparison with the extremely oligotrophic (nutrient-depleted) conditions in upper waters of the central North Pacific Ocean.…”

“…The free REE 3+ ion is thought to be the most reactive species, notably for adsorption onto biogenic particles in the upper water layers where plankton is most abundant. This adsorption is deemed to lead to ''fractionations" along the REE series akin to fractionations of stable isotopes of one element, for example Cd stable isotopes (de Baar et al, 2017c;and references therein). For the REE series such fractionation trend with increasing atomic number is the result of a balancing act between (i) the concentrations and REE-affinities of inorganic complexes in the seawater, and (ii) the concentrations and REE-affinities of the adsorbing agents on the surface of marine particles.…”

The effect of cell size on cellular Zn and Cd and Zn‐Cd‐CO2 colimitation of growth rate in marine diatoms

“…Consequently, the distributions of dissolved Cd and Zn, as well as their isotopic ratios in the global ocean, are profoundly influenced by the biological uptake of these metals in surface waters (Conway and John 2015; Vance et al 2017; Zhang et al 2019). For example, de Baar et al (2017) observed strong correlations between δ 114 Cd and dissolved concentrations of Cd and CO 2 in the surface waters of the Southern Ocean, all of which can be directly linked to biological uptake.…”