Sedimentary molybdenum and uranium : Improving proxies for deoxygenation in coastal depositional environments
Paul, K. Mareike ; van Helmond, Niels A.G.M. ; Slomp, Caroline P. ; Jokinen, Sami A. ; Virtasalo, Joonas J. ; Filipsson, Helena L. LU
and Jilbert, Tom
(2023)
In Chemical Geology
615.
- Abstract
Sedimentary molybdenum (Mo) and uranium (U) enrichments are widely used to reconstruct changes in bottom water oxygen conditions in aquatic environments. Until now, most studies using Mo and U have focused on restricted suboxic-euxinic basins and continental margin oxygen minimum zones (OMZs), leaving mildly reducing and oxic (but eutrophic) coastal depositional environments vastly understudied. Currently, it is unknown: (1) to what extent Mo and U enrichment factors (Mo- and U-EFs) can accurately reconstruct oxygen conditions in coastal sites experiencing mild deoxygenation, and (2) to what degree secondary (depositional environmental) factors impact Mo- and U-EFs. Here we investigate 18 coastal sites with varying bottom water redox... (More)
Sedimentary molybdenum (Mo) and uranium (U) enrichments are widely used to reconstruct changes in bottom water oxygen conditions in aquatic environments. Until now, most studies using Mo and U have focused on restricted suboxic-euxinic basins and continental margin oxygen minimum zones (OMZs), leaving mildly reducing and oxic (but eutrophic) coastal depositional environments vastly understudied. Currently, it is unknown: (1) to what extent Mo and U enrichment factors (Mo- and U-EFs) can accurately reconstruct oxygen conditions in coastal sites experiencing mild deoxygenation, and (2) to what degree secondary (depositional environmental) factors impact Mo- and U-EFs. Here we investigate 18 coastal sites with varying bottom water redox conditions, which we define by means of five “redox bins”, ranging from persistently oxic to persistently euxinic, from a variety of depositional environments. Our results demonstrate that Mo- and U-EF-based redox proxies and sedimentary Mo and U contents can be used to differentiate bottom water oxygen concentration among a range of modern coastal depositional environments. This is underpinned by the contrasting EFs of Mo and U along the redox gradient, which shows a substantial difference of Mo-EFs between redox bins 3–5 (ir/regularly suboxic – ir/regularly dysoxic – persistently oxic) and of U-EFs between redox bins 1–2 (persistently euxinic – ir/regularly euxinic). Surprisingly, we observe comparatively low redox proxy potential for U in environments of mild deoxygenation (redox bins 3–5). Further, we found that secondary factors can bias Mo-and U-EFs to such an extent that EFs do not reliably reflect bottom water redox conditions. We investigate the impact of limited Mo sedimentary sequestration in sulfidic depositional environments (i.e., the “basin reservoir effect”, equilibrium with FeMoS4), Fe/Mn-(oxy)(hydr)oxide “shuttling”, oxidative dissolution, the sulfate methane transition zone in the sediment, sedimentation rate, and the local Al background on Mo- and U-EFs.
(Less)
- author
- Paul, K. Mareike
; van Helmond, Niels A.G.M.
; Slomp, Caroline P.
; Jokinen, Sami A.
; Virtasalo, Joonas J.
; Filipsson, Helena L.
LU
and Jilbert, Tom
- organization
- publishing date
- 2023-01-05
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Coastal Sea, Enrichment factor, Hypoxia, Redox-sensitive, Trace metal
- in
- Chemical Geology
- volume
- 615
- article number
- 121203
- publisher
- Elsevier
- external identifiers
-
- scopus:85142181809
- ISSN
- 0009-2541
- DOI
- 10.1016/j.chemgeo.2022.121203
- project
- Tracing past bottom water oxygenation in the sea: a microanalytical approach to improve calcium carbonate based proxies (TOPICaL)
- language
- English
- LU publication?
- yes
- additional info
- Funding Information: We thank the captain, crew, and scientific participants on board R/V Skagerrak (2019) and R/V Pelagia (2019) for their assistance with the field work campaigns. We acknowledge the staff of the Kristineberg Marine Research Station and the Royal Netherlands Institute for Sea Research (NIOZ) for their support during the field campaigns. The GeoLab, especially Helen de Waard, Coen Mulder, Natasja Welters, and Arnold van Dijk are acknowledged for analytical assistance at Utrecht University. We thank Heini Ali-Kovero for analytical assistance at the University of Helsinki. We also thank Martijn Hermans and Ricardo Correia for helping with making figures, computing in R, and providing feedback. This research was funded by the Academy of Finland (grant numbers 1319956 and 1345962 ). Additional funding was provided by the Netherlands Organisation for Scientific Research (NWO; Vici-grant number 865.13.005), and the European Research Council (ERC Synergy Marix grant number 854088). This work was carried out under the program of the Netherlands Earth System Science Centre (NESSC), financially supported by the Ministry of Education , Culture and Science (OCW). HLF acknowledges support by the Swedish Research Council VR (grant number 2017-04190 ). Funding Information: We thank the captain, crew, and scientific participants on board R/V Skagerrak (2019) and R/V Pelagia (2019) for their assistance with the field work campaigns. We acknowledge the staff of the Kristineberg Marine Research Station and the Royal Netherlands Institute for Sea Research (NIOZ) for their support during the field campaigns. The GeoLab, especially Helen de Waard, Coen Mulder, Natasja Welters, and Arnold van Dijk are acknowledged for analytical assistance at Utrecht University. We thank Heini Ali-Kovero for analytical assistance at the University of Helsinki. We also thank Martijn Hermans and Ricardo Correia for helping with making figures, computing in R, and providing feedback. This research was funded by the Academy of Finland (grant numbers 1319956 and 1345962). Additional funding was provided by the Netherlands Organisation for Scientific Research (NWO; Vici-grant number 865.13.005), and the European Research Council (ERC Synergy Marix grant number 854088). This work was carried out under the program of the Netherlands Earth System Science Centre (NESSC), financially supported by the Ministry of Education, Culture and Science (OCW). HLF acknowledges support by the Swedish Research Council VR (grant number 2017-04190). Publisher Copyright: © 2022 The Authors
- id
- c14e2620-c4f8-4bb0-9fc3-491e41076eef
- date added to LUP
- 2022-12-01 08:05:14
- date last changed
- 2024-05-27 14:29:51
@article{c14e2620-c4f8-4bb0-9fc3-491e41076eef,
abstract = {{<p>Sedimentary molybdenum (Mo) and uranium (U) enrichments are widely used to reconstruct changes in bottom water oxygen conditions in aquatic environments. Until now, most studies using Mo and U have focused on restricted suboxic-euxinic basins and continental margin oxygen minimum zones (OMZs), leaving mildly reducing and oxic (but eutrophic) coastal depositional environments vastly understudied. Currently, it is unknown: (1) to what extent Mo and U enrichment factors (Mo- and U-EFs) can accurately reconstruct oxygen conditions in coastal sites experiencing mild deoxygenation, and (2) to what degree secondary (depositional environmental) factors impact Mo- and U-EFs. Here we investigate 18 coastal sites with varying bottom water redox conditions, which we define by means of five “redox bins”, ranging from persistently oxic to persistently euxinic, from a variety of depositional environments. Our results demonstrate that Mo- and U-EF-based redox proxies and sedimentary Mo and U contents can be used to differentiate bottom water oxygen concentration among a range of modern coastal depositional environments. This is underpinned by the contrasting EFs of Mo and U along the redox gradient, which shows a substantial difference of Mo-EFs between redox bins 3–5 (ir/regularly suboxic – ir/regularly dysoxic – persistently oxic) and of U-EFs between redox bins 1–2 (persistently euxinic – ir/regularly euxinic). Surprisingly, we observe comparatively low redox proxy potential for U in environments of mild deoxygenation (redox bins 3–5). Further, we found that secondary factors can bias Mo-and U-EFs to such an extent that EFs do not reliably reflect bottom water redox conditions. We investigate the impact of limited Mo sedimentary sequestration in sulfidic depositional environments (i.e., the “basin reservoir effect”, equilibrium with FeMoS<sub>4</sub>), Fe/Mn-(oxy)(hydr)oxide “shuttling”, oxidative dissolution, the sulfate methane transition zone in the sediment, sedimentation rate, and the local Al background on Mo- and U-EFs.</p>}},
author = {{Paul, K. Mareike and van Helmond, Niels A.G.M. and Slomp, Caroline P. and Jokinen, Sami A. and Virtasalo, Joonas J. and Filipsson, Helena L. and Jilbert, Tom}},
issn = {{0009-2541}},
keywords = {{Coastal Sea; Enrichment factor; Hypoxia; Redox-sensitive; Trace metal}},
language = {{eng}},
month = {{01}},
publisher = {{Elsevier}},
series = {{Chemical Geology}},
title = {{Sedimentary molybdenum and uranium : Improving proxies for deoxygenation in coastal depositional environments}},
url = {{http://dx.doi.org/10.1016/j.chemgeo.2022.121203}},
doi = {{10.1016/j.chemgeo.2022.121203}},
volume = {{615}},
year = {{2023}},
}