Influence of pH and Dissolved Organic Matter on Iron Speciation and Apparent Iron Solubility in the Peruvian Shelf and Slope Region
The chemical speciation of iron (Fe) in oceans is influenced by ambient pH, dissolved oxygen, and the concentrations and strengths of the binding sites of dissolved organic matter (DOM). Here, we derived new nonideal competitive adsorption (NICA) constants for Fe(III) binding to marine DOM via pH-Fe...
Published in: | Environmental Science & Technology |
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ACS (American Chemical Society)
2021
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Online Access: | https://oceanrep.geomar.de/id/eprint/52761/ https://oceanrep.geomar.de/id/eprint/52761/1/Zhu%20et%20al.pdf https://oceanrep.geomar.de/id/eprint/52761/7/gbc21015-sup-0001-2020gb006538-si-2.pdf https://doi.org/10.1021/acs.est.1c02477 |
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ftoceanrep:oai:oceanrep.geomar.de:52761 2024-02-11T10:07:34+01:00 Influence of pH and Dissolved Organic Matter on Iron Speciation and Apparent Iron Solubility in the Peruvian Shelf and Slope Region Zhu, Kechen Hopwood, Mark J. Groenenberg, Jan E. Engel, Anja Achterberg, Eric P. Gledhill, Martha 2021-06-10 text https://oceanrep.geomar.de/id/eprint/52761/ https://oceanrep.geomar.de/id/eprint/52761/1/Zhu%20et%20al.pdf https://oceanrep.geomar.de/id/eprint/52761/7/gbc21015-sup-0001-2020gb006538-si-2.pdf https://doi.org/10.1021/acs.est.1c02477 en eng ACS (American Chemical Society) https://oceanrep.geomar.de/id/eprint/52761/1/Zhu%20et%20al.pdf https://oceanrep.geomar.de/id/eprint/52761/7/gbc21015-sup-0001-2020gb006538-si-2.pdf Zhu, K., Hopwood, M. J. , Groenenberg, J. E., Engel, A. , Achterberg, E. P. and Gledhill, M. (2021) Influence of pH and Dissolved Organic Matter on Iron Speciation and Apparent Iron Solubility in the Peruvian Shelf and Slope Region. Environmental Science & Technology, 55 (13). pp. 9372-9383. DOI 10.1021/acs.est.1c02477 <https://doi.org/10.1021/acs.est.1c02477>. doi:10.1021/acs.est.1c02477 info:eu-repo/semantics/restrictedAccess Article PeerReviewed 2021 ftoceanrep https://doi.org/10.1021/acs.est.1c02477 2024-01-15T00:23:30Z The chemical speciation of iron (Fe) in oceans is influenced by ambient pH, dissolved oxygen, and the concentrations and strengths of the binding sites of dissolved organic matter (DOM). Here, we derived new nonideal competitive adsorption (NICA) constants for Fe(III) binding to marine DOM via pH-Fe titrations. We used the constants to calculate Fe(III) speciation and derive the apparent Fe(III) solubility (SFe(III)app) in the ambient water column across the Peruvian shelf and slope region. We define SFe(III)app as the sum of aqueous inorganic Fe(III) species and Fe(III) bound to DOM at a free Fe (Fe3+) concentration equal to the limiting solubility of Fe hydroxide (Fe(OH)3(s)). A ca. twofold increase in SFe(III)app in the oxygen minimum zone (OMZ) compared to surface waters is predicted. The increase results from a one order of magnitude decrease in H+ concentration which impacts both Fe(III) hydroxide solubility and organic complexation. A correlation matrix suggests that changes in pH have a larger impact on SFe(III)app and Fe(III) speciation than DOM in this region. Using Fe(II) measurements, we calculated ambient DFe(III) and compared the value with the predicted SFe(III)app. The underlying distribution of ambient DFe(III) largely reflected the predicted SFe(III)app, indicating that decreased pH as a result of OMZ intensification and ocean acidification may increase SFe(III)app with potential impacts on surface DFe inventories. Article in Journal/Newspaper Ocean acidification OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) Environmental Science & Technology |
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Open Polar |
collection |
OceanRep (GEOMAR Helmholtz Centre für Ocean Research Kiel) |
op_collection_id |
ftoceanrep |
language |
English |
description |
The chemical speciation of iron (Fe) in oceans is influenced by ambient pH, dissolved oxygen, and the concentrations and strengths of the binding sites of dissolved organic matter (DOM). Here, we derived new nonideal competitive adsorption (NICA) constants for Fe(III) binding to marine DOM via pH-Fe titrations. We used the constants to calculate Fe(III) speciation and derive the apparent Fe(III) solubility (SFe(III)app) in the ambient water column across the Peruvian shelf and slope region. We define SFe(III)app as the sum of aqueous inorganic Fe(III) species and Fe(III) bound to DOM at a free Fe (Fe3+) concentration equal to the limiting solubility of Fe hydroxide (Fe(OH)3(s)). A ca. twofold increase in SFe(III)app in the oxygen minimum zone (OMZ) compared to surface waters is predicted. The increase results from a one order of magnitude decrease in H+ concentration which impacts both Fe(III) hydroxide solubility and organic complexation. A correlation matrix suggests that changes in pH have a larger impact on SFe(III)app and Fe(III) speciation than DOM in this region. Using Fe(II) measurements, we calculated ambient DFe(III) and compared the value with the predicted SFe(III)app. The underlying distribution of ambient DFe(III) largely reflected the predicted SFe(III)app, indicating that decreased pH as a result of OMZ intensification and ocean acidification may increase SFe(III)app with potential impacts on surface DFe inventories. |
format |
Article in Journal/Newspaper |
author |
Zhu, Kechen Hopwood, Mark J. Groenenberg, Jan E. Engel, Anja Achterberg, Eric P. Gledhill, Martha |
spellingShingle |
Zhu, Kechen Hopwood, Mark J. Groenenberg, Jan E. Engel, Anja Achterberg, Eric P. Gledhill, Martha Influence of pH and Dissolved Organic Matter on Iron Speciation and Apparent Iron Solubility in the Peruvian Shelf and Slope Region |
author_facet |
Zhu, Kechen Hopwood, Mark J. Groenenberg, Jan E. Engel, Anja Achterberg, Eric P. Gledhill, Martha |
author_sort |
Zhu, Kechen |
title |
Influence of pH and Dissolved Organic Matter on Iron Speciation and Apparent Iron Solubility in the Peruvian Shelf and Slope Region |
title_short |
Influence of pH and Dissolved Organic Matter on Iron Speciation and Apparent Iron Solubility in the Peruvian Shelf and Slope Region |
title_full |
Influence of pH and Dissolved Organic Matter on Iron Speciation and Apparent Iron Solubility in the Peruvian Shelf and Slope Region |
title_fullStr |
Influence of pH and Dissolved Organic Matter on Iron Speciation and Apparent Iron Solubility in the Peruvian Shelf and Slope Region |
title_full_unstemmed |
Influence of pH and Dissolved Organic Matter on Iron Speciation and Apparent Iron Solubility in the Peruvian Shelf and Slope Region |
title_sort |
influence of ph and dissolved organic matter on iron speciation and apparent iron solubility in the peruvian shelf and slope region |
publisher |
ACS (American Chemical Society) |
publishDate |
2021 |
url |
https://oceanrep.geomar.de/id/eprint/52761/ https://oceanrep.geomar.de/id/eprint/52761/1/Zhu%20et%20al.pdf https://oceanrep.geomar.de/id/eprint/52761/7/gbc21015-sup-0001-2020gb006538-si-2.pdf https://doi.org/10.1021/acs.est.1c02477 |
genre |
Ocean acidification |
genre_facet |
Ocean acidification |
op_relation |
https://oceanrep.geomar.de/id/eprint/52761/1/Zhu%20et%20al.pdf https://oceanrep.geomar.de/id/eprint/52761/7/gbc21015-sup-0001-2020gb006538-si-2.pdf Zhu, K., Hopwood, M. J. , Groenenberg, J. E., Engel, A. , Achterberg, E. P. and Gledhill, M. (2021) Influence of pH and Dissolved Organic Matter on Iron Speciation and Apparent Iron Solubility in the Peruvian Shelf and Slope Region. Environmental Science & Technology, 55 (13). pp. 9372-9383. DOI 10.1021/acs.est.1c02477 <https://doi.org/10.1021/acs.est.1c02477>. doi:10.1021/acs.est.1c02477 |
op_rights |
info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1021/acs.est.1c02477 |
container_title |
Environmental Science & Technology |
_version_ |
1790606191042232320 |