Re-assessing the Influence of Particle-hosted Sulphide Precipitation on the Marine Cadmium Cycle

Gregory F. de Souza; Derek Vance; Matthias Sieber; Tim M. Conway; Susan H. Little

doi:10.1016/j.gca.2022.02.009

Re-assessing the Influence of Particle-hosted Sulphide Precipitation on the Marine Cadmium Cycle

Gregory F. de Souza, Derek Vance, Matthias Sieber, Tim M. Conway, Susan H. Little

University of South Florida

Research output: Contribution to journal › Article › peer-review

Abstract

It has been inferred that the marine distributions of the micronutrient cadmium (Cd) and its <a title="Learn more about stable isotope from ScienceDirect's AI-generated Topic Pages"> stable isotope </a> composition (expressed as δ 114 Cd) bear widespread and unambiguous evidence for loss of Cd from the shallow water column through the formation of particle-associated <a title="Learn more about cadmium sulphide from ScienceDirect's AI-generated Topic Pages"> cadmium sulphide </a> (CdS) in oxygen minimum zones (OMZs). In this review, we bring together elemental and isotopic datasets from the dissolved and particulate Cd pools in order to unravel the multiple, overlapping controls on the distribution of Cd and δ 114 Cd, and demonstrate that the global dataset challenges this view. By far the most important control on the marine Cd distribution is the extreme plasticity in the cadmium:phosphorus (Cd:P) <a title="Learn more about stoichiometry from ScienceDirect's AI-generated Topic Pages"> stoichiometry </a> of <a title="Learn more about biological uptake from ScienceDirect's AI-generated Topic Pages"> biological uptake </a> and, in consequence, particulate export. We show that δ 114 Cd systematics in low-latitude OMZs that have been taken to reflect Cd loss in fact come about mainly through the interaction between the physical circulation and the variable stoichiometry of biological Cd uptake at high and low latitudes; water-column evidence for Cd loss is thus much less widespread than has previously been inferred. Subtle but consistent signals in particulate elemental and dissolved isotopic data from the open tropical Atlantic and Pacific Oceans allow us to identify the signal of a Cd loss associated with the oxycline of the shallow tropical subsurface, as has previously been suggested. However, this Cd loss appears to be ubiquitous throughout the tropics, rather than confined to oxygen-poor waters, speaking against CdS formation as the driving mechanism. Although its true identity remains unknown, this tropical Cd loss may be related to biological activity. Finally, we show how the processes we consider – the <a title="Learn more about remineralisation from ScienceDirect's AI-generated Topic Pages"> remineralisation </a> of biogenic particles with variable Cd:P stoichiometry, and ubiquitous tropical oxycline Cd loss – bear upon the role of particle-hosted CdS formation in the marine mass balance of Cd, which is likely to be much smaller than recent estimates have suggested.

Original language	American English
Journal	Geochimica et Cosmochimica Acta
Volume	322
DOIs	https://doi.org/10.1016/j.gca.2022.02.009
State	Published - Jan 1 2022

Keywords

GEOTRACES
Marine biogeochemistry
Southern Ocean
Cadmium sulfide
Oxygen-deficient zone
Cadmium isotopes

Disciplines

Life Sciences

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10.1016/j.gca.2022.02.009License: CC BY

Re-assessing the Influence of Particle-hosted Sulphide PrecipitatFinal published version, 4.33 MBLicense: CC BY

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@article{38af82c93113499c87d1c6dc6b42ec13,

title = "Re-assessing the Influence of Particle-hosted Sulphide Precipitation on the Marine Cadmium Cycle",

abstract = " It has been inferred that the marine distributions of the micronutrient cadmium (Cd) and its stable isotope composition (expressed as δ 114 Cd) bear widespread and unambiguous evidence for loss of Cd from the shallow water column through the formation of particle-associated cadmium sulphide (CdS) in oxygen minimum zones (OMZs). In this review, we bring together elemental and isotopic datasets from the dissolved and particulate Cd pools in order to unravel the multiple, overlapping controls on the distribution of Cd and δ 114 Cd, and demonstrate that the global dataset challenges this view. By far the most important control on the marine Cd distribution is the extreme plasticity in the cadmium:phosphorus (Cd:P) stoichiometry of biological uptake and, in consequence, particulate export. We show that δ 114 Cd systematics in low-latitude OMZs that have been taken to reflect Cd loss in fact come about mainly through the interaction between the physical circulation and the variable stoichiometry of biological Cd uptake at high and low latitudes; water-column evidence for Cd loss is thus much less widespread than has previously been inferred. Subtle but consistent signals in particulate elemental and dissolved isotopic data from the open tropical Atlantic and Pacific Oceans allow us to identify the signal of a Cd loss associated with the oxycline of the shallow tropical subsurface, as has previously been suggested. However, this Cd loss appears to be ubiquitous throughout the tropics, rather than confined to oxygen-poor waters, speaking against CdS formation as the driving mechanism. Although its true identity remains unknown, this tropical Cd loss may be related to biological activity. Finally, we show how the processes we consider – the remineralisation of biogenic particles with variable Cd:P stoichiometry, and ubiquitous tropical oxycline Cd loss – bear upon the role of particle-hosted CdS formation in the marine mass balance of Cd, which is likely to be much smaller than recent estimates have suggested. ",

keywords = "GEOTRACES, Marine biogeochemistry, Southern Ocean, Cadmium sulfide, Oxygen-deficient zone, Cadmium isotopes",

author = "{de Souza}, {Gregory F.} and Derek Vance and Matthias Sieber and Conway, {Tim M.} and Little, {Susan H.}",

year = "2022",

month = jan,

day = "1",

doi = "10.1016/j.gca.2022.02.009",

language = "American English",

volume = "322",

journal = "Geochimica et Cosmochimica Acta",

}

TY - JOUR

T1 - Re-assessing the Influence of Particle-hosted Sulphide Precipitation on the Marine Cadmium Cycle

AU - de Souza, Gregory F.

AU - Vance, Derek

AU - Sieber, Matthias

AU - Conway, Tim M.

AU - Little, Susan H.

PY - 2022/1/1

Y1 - 2022/1/1

N2 - It has been inferred that the marine distributions of the micronutrient cadmium (Cd) and its stable isotope composition (expressed as δ 114 Cd) bear widespread and unambiguous evidence for loss of Cd from the shallow water column through the formation of particle-associated cadmium sulphide (CdS) in oxygen minimum zones (OMZs). In this review, we bring together elemental and isotopic datasets from the dissolved and particulate Cd pools in order to unravel the multiple, overlapping controls on the distribution of Cd and δ 114 Cd, and demonstrate that the global dataset challenges this view. By far the most important control on the marine Cd distribution is the extreme plasticity in the cadmium:phosphorus (Cd:P) stoichiometry of biological uptake and, in consequence, particulate export. We show that δ 114 Cd systematics in low-latitude OMZs that have been taken to reflect Cd loss in fact come about mainly through the interaction between the physical circulation and the variable stoichiometry of biological Cd uptake at high and low latitudes; water-column evidence for Cd loss is thus much less widespread than has previously been inferred. Subtle but consistent signals in particulate elemental and dissolved isotopic data from the open tropical Atlantic and Pacific Oceans allow us to identify the signal of a Cd loss associated with the oxycline of the shallow tropical subsurface, as has previously been suggested. However, this Cd loss appears to be ubiquitous throughout the tropics, rather than confined to oxygen-poor waters, speaking against CdS formation as the driving mechanism. Although its true identity remains unknown, this tropical Cd loss may be related to biological activity. Finally, we show how the processes we consider – the remineralisation of biogenic particles with variable Cd:P stoichiometry, and ubiquitous tropical oxycline Cd loss – bear upon the role of particle-hosted CdS formation in the marine mass balance of Cd, which is likely to be much smaller than recent estimates have suggested.

AB - It has been inferred that the marine distributions of the micronutrient cadmium (Cd) and its stable isotope composition (expressed as δ 114 Cd) bear widespread and unambiguous evidence for loss of Cd from the shallow water column through the formation of particle-associated cadmium sulphide (CdS) in oxygen minimum zones (OMZs). In this review, we bring together elemental and isotopic datasets from the dissolved and particulate Cd pools in order to unravel the multiple, overlapping controls on the distribution of Cd and δ 114 Cd, and demonstrate that the global dataset challenges this view. By far the most important control on the marine Cd distribution is the extreme plasticity in the cadmium:phosphorus (Cd:P) stoichiometry of biological uptake and, in consequence, particulate export. We show that δ 114 Cd systematics in low-latitude OMZs that have been taken to reflect Cd loss in fact come about mainly through the interaction between the physical circulation and the variable stoichiometry of biological Cd uptake at high and low latitudes; water-column evidence for Cd loss is thus much less widespread than has previously been inferred. Subtle but consistent signals in particulate elemental and dissolved isotopic data from the open tropical Atlantic and Pacific Oceans allow us to identify the signal of a Cd loss associated with the oxycline of the shallow tropical subsurface, as has previously been suggested. However, this Cd loss appears to be ubiquitous throughout the tropics, rather than confined to oxygen-poor waters, speaking against CdS formation as the driving mechanism. Although its true identity remains unknown, this tropical Cd loss may be related to biological activity. Finally, we show how the processes we consider – the remineralisation of biogenic particles with variable Cd:P stoichiometry, and ubiquitous tropical oxycline Cd loss – bear upon the role of particle-hosted CdS formation in the marine mass balance of Cd, which is likely to be much smaller than recent estimates have suggested.

KW - GEOTRACES

KW - Marine biogeochemistry

KW - Southern Ocean

KW - Cadmium sulfide

KW - Oxygen-deficient zone

KW - Cadmium isotopes

UR - https://digitalcommons.usf.edu/msc_facpub/2476

U2 - 10.1016/j.gca.2022.02.009

DO - 10.1016/j.gca.2022.02.009

M3 - Article

VL - 322

JO - Geochimica et Cosmochimica Acta

JF - Geochimica et Cosmochimica Acta

ER -

Re-assessing the Influence of Particle-hosted Sulphide Precipitation on the Marine Cadmium Cycle

Abstract

Keywords

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