The Cycling of Iron, Zinc and Cadmium in the North East Pacific Ocean – Insights from Stable Isotopes
Dissolved stable isotope ratios of the transition metals provide useful information, both for understanding the cycling of these bioactive trace elements through the oceans, and tracing their marine sources and sinks. Here, we present seawater dissolved Fe, Zn and Cd concentration and stable isotope...
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Online Access: | https://digitalcommons.usf.edu/geo_facpub/1504 https://doi.org/10.1016/j.gca.2015.05.023 |
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ftusouthflorida:oai:digitalcommons.usf.edu:geo_facpub-2528 2023-07-30T04:05:35+02:00 The Cycling of Iron, Zinc and Cadmium in the North East Pacific Ocean – Insights from Stable Isotopes Conway, Tim M. John, Seth G. 2015-09-01T07:00:00Z https://digitalcommons.usf.edu/geo_facpub/1504 https://doi.org/10.1016/j.gca.2015.05.023 unknown Digital Commons @ University of South Florida https://digitalcommons.usf.edu/geo_facpub/1504 doi:10.1016/j.gca.2015.05.023 https://doi.org/10.1016/j.gca.2015.05.023 School of Geosciences Faculty and Staff Publications Earth Sciences article 2015 ftusouthflorida https://doi.org/10.1016/j.gca.2015.05.023 2023-07-13T20:43:52Z Dissolved stable isotope ratios of the transition metals provide useful information, both for understanding the cycling of these bioactive trace elements through the oceans, and tracing their marine sources and sinks. Here, we present seawater dissolved Fe, Zn and Cd concentration and stable isotope ratio (δ56Fe, δ66Zn, and δ114Cd) profiles from two stations in the Pacific Ocean, the SAFe Station (30°N 140°W) in the subtropical North East Pacific from the GEOTRACES IC2 cruise, and the marginal San Pedro Basin (33.8°N 118.4°W) within the South California Bight. These data represent, to our knowledge, the first full-water column profiles for δ66Zn and δ56Fe from the open-ocean North Pacific, and the first observations of dissolved δ66Zn and δ114Cd in a low-oxygen marginal basin. At the SAFe station, δ56Fe is isotopically lighter throughout the water column (−0.6 to +0.1‰, relative to IRRM-014) compared to the North Atlantic, suggesting significant differences in Fe sources or Fe cycling between these two ocean basins. A broad minimum in δ56Fe associated with the North Pacific oxygen minimum zone (OMZ; <75 μmol kg−1 dissolved oxygen; ∼550–2000 m depth) is consistent with reductive sediments along the California margin being an important source of dissolved Fe to the North Pacific. Other processes which may influence δ56Fe at SAFe include biological cycling in the upper ocean, and input of Fe from hydrothermal vents and oxic sediments below the OMZ. Zn and Cd concentration profiles at both stations broadly match the distribution of the macronutrients silicate and phosphate, respectively. At SAFe, δ114Cd increases towards the surface, reflecting the biological preference for assimilation of lighter Cd isotopes, while negative Cd∗ (−0.12) associated with low oxygen waters supports the recently proposed hypothesis of water-column CdS precipitation. In contrast to δ114Cd, δ66Zn at SAFe decreases towards the surface ocean, perhaps due to scavenging of isotopically heavy Zn, while at intermediate depths δ66Zn provides ... Article in Journal/Newspaper North Atlantic University of South Florida St. Petersburg: Digital USFSP Pacific Geochimica et Cosmochimica Acta 164 262 283 |
institution |
Open Polar |
collection |
University of South Florida St. Petersburg: Digital USFSP |
op_collection_id |
ftusouthflorida |
language |
unknown |
topic |
Earth Sciences |
spellingShingle |
Earth Sciences Conway, Tim M. John, Seth G. The Cycling of Iron, Zinc and Cadmium in the North East Pacific Ocean – Insights from Stable Isotopes |
topic_facet |
Earth Sciences |
description |
Dissolved stable isotope ratios of the transition metals provide useful information, both for understanding the cycling of these bioactive trace elements through the oceans, and tracing their marine sources and sinks. Here, we present seawater dissolved Fe, Zn and Cd concentration and stable isotope ratio (δ56Fe, δ66Zn, and δ114Cd) profiles from two stations in the Pacific Ocean, the SAFe Station (30°N 140°W) in the subtropical North East Pacific from the GEOTRACES IC2 cruise, and the marginal San Pedro Basin (33.8°N 118.4°W) within the South California Bight. These data represent, to our knowledge, the first full-water column profiles for δ66Zn and δ56Fe from the open-ocean North Pacific, and the first observations of dissolved δ66Zn and δ114Cd in a low-oxygen marginal basin. At the SAFe station, δ56Fe is isotopically lighter throughout the water column (−0.6 to +0.1‰, relative to IRRM-014) compared to the North Atlantic, suggesting significant differences in Fe sources or Fe cycling between these two ocean basins. A broad minimum in δ56Fe associated with the North Pacific oxygen minimum zone (OMZ; <75 μmol kg−1 dissolved oxygen; ∼550–2000 m depth) is consistent with reductive sediments along the California margin being an important source of dissolved Fe to the North Pacific. Other processes which may influence δ56Fe at SAFe include biological cycling in the upper ocean, and input of Fe from hydrothermal vents and oxic sediments below the OMZ. Zn and Cd concentration profiles at both stations broadly match the distribution of the macronutrients silicate and phosphate, respectively. At SAFe, δ114Cd increases towards the surface, reflecting the biological preference for assimilation of lighter Cd isotopes, while negative Cd∗ (−0.12) associated with low oxygen waters supports the recently proposed hypothesis of water-column CdS precipitation. In contrast to δ114Cd, δ66Zn at SAFe decreases towards the surface ocean, perhaps due to scavenging of isotopically heavy Zn, while at intermediate depths δ66Zn provides ... |
format |
Article in Journal/Newspaper |
author |
Conway, Tim M. John, Seth G. |
author_facet |
Conway, Tim M. John, Seth G. |
author_sort |
Conway, Tim M. |
title |
The Cycling of Iron, Zinc and Cadmium in the North East Pacific Ocean – Insights from Stable Isotopes |
title_short |
The Cycling of Iron, Zinc and Cadmium in the North East Pacific Ocean – Insights from Stable Isotopes |
title_full |
The Cycling of Iron, Zinc and Cadmium in the North East Pacific Ocean – Insights from Stable Isotopes |
title_fullStr |
The Cycling of Iron, Zinc and Cadmium in the North East Pacific Ocean – Insights from Stable Isotopes |
title_full_unstemmed |
The Cycling of Iron, Zinc and Cadmium in the North East Pacific Ocean – Insights from Stable Isotopes |
title_sort |
cycling of iron, zinc and cadmium in the north east pacific ocean – insights from stable isotopes |
publisher |
Digital Commons @ University of South Florida |
publishDate |
2015 |
url |
https://digitalcommons.usf.edu/geo_facpub/1504 https://doi.org/10.1016/j.gca.2015.05.023 |
geographic |
Pacific |
geographic_facet |
Pacific |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
School of Geosciences Faculty and Staff Publications |
op_relation |
https://digitalcommons.usf.edu/geo_facpub/1504 doi:10.1016/j.gca.2015.05.023 https://doi.org/10.1016/j.gca.2015.05.023 |
op_doi |
https://doi.org/10.1016/j.gca.2015.05.023 |
container_title |
Geochimica et Cosmochimica Acta |
container_volume |
164 |
container_start_page |
262 |
op_container_end_page |
283 |
_version_ |
1772817607942995968 |