Cadmium isotopic composition in the ocean

Lacan, F.; François, Roger; Ji, Yongcheng; Sherrell, Robert M.

doi:10.1016/j.gca.2006.07.036

Cited by 159 publications

(96 citation statements)

References 35 publications

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“…= 0.9986 ± 0.0006; ref. 8) and the growing literature for other biologically active transition metals, whereby microorganisms exhibit a general preference for the light isotopes of a given element, e.g., Mo (12), Cu (13), Zn (14), Fe (15), and Ni (16). We rule out adsorption as the cause of the light isotopic fractionation observed for Cd in cultured cells, because a subset of cells plunged into the growth medium for a short time (∼10 s) resulted in no fractionation of Cd isotopes ( Fig.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Nonspecific uptake and homeostasis drive the oceanic cadmium cycle

Horner

Lee

Henderson

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

103

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The global marine distributions of Cd and phosphate are closely correlated, which has led to Cd being considered as a marine micronutrient, despite its toxicity to life. The explanation for this nutrient-like behavior is unknown because there is only one identified biochemical function for Cd, an unusual Cd/Zn carbonic anhydrase. Recent developments in Cd isotope mass spectrometry have revealed that Cd uptake by phytoplankton causes isotopic fractionation in the open ocean and in culture. Here we investigate the physiochemical pathways that fractionate Cd isotopes by performing subcellular Cd isotope analysis on genetically modified microorganisms. We find that expression of the Cd/Zn carbonic anhydrase makes no difference to the Cd isotope composition of whole cells. Instead, a large proportion of the Cd is partitioned into cell membranes with a similar direction and magnitude of Cd isotopic fractionation to that seen in surface seawater. This observation is well explained if Cd is mistakenly imported with other divalent metals and subsequently managed by binding within the cell to avoid toxicity. This process may apply to other divalent metals, whereby nonspecific uptake and subsequent homeostasis may contribute to elemental and isotopic distributions in seawater, even for elements commonly considered as micronutrients.biological fractionation | isotope geochemistry | metal homeostasis | subcellular analysis | trace metal I n addition to the macronutrients nitrate, phosphate, and silicate, marine phytoplankton require many essential metals to function correctly (1). The uptake and utilization of these micronutrients results in large vertical isotopic and concentration gradients for many transition metals in seawater (2). In the open ocean, Cd concentrations are as low as a few picomoles per kilogram (2, 3), with associated highly fractionated Cd isotopic compositions of up to several permil ( Fig. 1) (4). In culture, phytoplankton consume small quantities of Cd (5-7) and exhibit light Cd isotope compositions (8). Taken together, the available data suggest that the marine geochemistry of Cd is dominated by nutrient-like processes (i.e., required uptake). However, only one biochemical function for Cd is known: CdCA1, a Cd/Zn carbonic anhydrase from the marine diatom Thalassiosira weissflogii (9, 10). Although ubiquitous in natural waters (11), CdCA1 is absent in numerous phytoplankton including coccolithophores, cyanobacteria, archaea, and several species of diatom (11) (Table S1), and it is thus debateable whether the expression of this single enzyme can account for the nutrient-like distribution of Cd in the global ocean. Here we examine the isotopic fractionation of Cd associated with CdCA1 that has been expressed in vivo by the model microorganism, Escherichia coli. Because E. coli has no inherent use for Cd, our experimental design permits comparison of cultures both overexpressing and not expressing CdCA1 in otherwise identical experiments. Using a systematic experimental approach, we are able to identify ...

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Section: Resultsmentioning

confidence: 99%

“…1) (4). In culture, phytoplankton consume small quantities of Cd (5-7) and exhibit light Cd isotope compositions (8). Taken together, the available data suggest that the marine geochemistry of Cd is dominated by nutrient-like processes (i.e., required uptake).…”

mentioning

confidence: 96%

Nonspecific uptake and homeostasis drive the oceanic cadmium cycle

Horner

Lee

Henderson

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

103

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“…As required for precise measurements of Cd isotopes, Cd was extracted from the sample matrix, with 1) nearly 100% recovery, 2) complete removal of isobars and the interference elements (mainly Pd, Sn, In, Zn, Ge, Se, Ru, Mo, K, Ca Na, and Mg), 3) no isotope fractionation 5,15,33 We will discuss the chromatographic separation efficiency based on these three factors mentioned above.…”

Section: Resultsmentioning

confidence: 99%

“…[3][4][5][6][7][8] Especially, the recent advent in multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) has extended dramatically the range of applications of stable Cd isotopes as tracers in natural systems. 9,10 Cd isotope analyses have been applied in order to investigate the evolution of celestial bodies, [11][12][13] mineral genesis and material source, 7,14 paleo-ocean environments, [15][16][17][18][19] and environmental cadmium pollution sources. 3,4,8,[20][21][22] Furthermore, Wei et al 6 suggested that Cd isotope fractionation in Cd hyperaccumulator plants could apply new insights in the enrichment mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Chromatographic Separation of Cd from Plants via Anion-Exchange Resin for an Isotope Determination by Multiple Collector ICP-MS

et al. 2017

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“…By comparing Fe-limited highnutrient, low-chlorophyll areas to Fe-sufficient areas, Cullen (2006) proposed that the kink in the global Cd-P relationship could be a direct consequence of different fractionations in Fe-replete and Fe-deficient conditions. Recent analytical developments allowing Cd isotope measurements (Lacan et al 2006;Gault-Ringold et al 2012) will probably help to constrain these mechanisms.…”

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confidence: 99%

Off Congo waters (Angola Basin, Atlantic Ocean): A hot spot for cadmium‐phosphate fractionation

Waeles

Maguer

Baurand

et al. 2013

Limnology & Oceanography

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We report the distribution of cadmium at 13 stations along 5.83uS in the Angola Basin. The studied area (which is influenced by the plume of the Congo River, doming, and relatively high primary production) is characterized by relatively low-circulation regime, which results in a strong oxygen minimum. In subsurface, very low cadmium : phosphate (Cd : P) ratios (0.05-0.10 nmol L 21 : mmol L 21 ) were observed below the euphotic zone (depth range 5 50-200 m), indicating that mineralization is the main process explaining the Cd-P fractionation. Cd-P decoupling is not restricted to subsurface waters, but occurs also throughout the oxygen minimum zone. An isopycnal analysis of the Cd : P ratio throughout the Atlantic Ocean shows that upper and intermediate waters in the South-east Atlantic are highly altered in terms of Cd-P properties. Benthic inputs at 4000 m were associated with degradation of organic matter with an important siliceous component, but were not accompanied by substantial changes in the Cd : P ratio.Understanding how the oceanic cadmium : phosphate (Cd : P) relationship in the ocean is governed has strong implications in the use of foraminiferal Cd as a paleoceanographic tracer of phosphate (Boyle 1988). Different studies integrating data sets available for the global ocean (de Baar et al. 1994;Elderfield and Rickaby 2000) have shown that upper-ocean waters are strongly depleted in both Cd and P; whereas, the old deep waters of the North Pacific are the most enriched, with Cd and P concentrations of , 1 nmol L 21 and , 3 mmol L 21 , respectively (Cd : P 5 0.35 nmol L 21 : mmol L 21 ). Between these two extremes, deviations have been evidenced indicating the preferential removal of Cd relative to P from surface waters. A comparison between each deep ocean reveals the particularity of the North Atlantic Deep Waters (NADW), where Cd and P concentrations (, 0.25 nmol L 21 and 1.3 mmol L 21 , respectively) and the resulting Cd : P ratio (, 0.2 nmol L 21 : mmol L 21 ) are lower than elsewhere. The specificity of the NADW in terms of Cd and P concentrations has been attributed to the more recent formation of its deep waters as compared with other oceans (Elderfield and Rickaby 2000). However, the reason for such a low Cd : P ratio has not been fully elucidated and the 'kink' (a pronounced break in the slope at P , 1.3 mmol L 21 ), although extensively discussed, remains elusive.

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Cadmium isotopic composition in the ocean

Cited by 159 publications

References 35 publications

Nonspecific uptake and homeostasis drive the oceanic cadmium cycle

Nonspecific uptake and homeostasis drive the oceanic cadmium cycle

Chromatographic Separation of Cd from Plants via Anion-Exchange Resin for an Isotope Determination by Multiple Collector ICP-MS

Off Congo waters (Angola Basin, Atlantic Ocean): A hot spot for cadmium‐phosphate fractionation

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