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Foraminifera Iodine to Calcium Ratios: Approach and Cleaning

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dc.contributor.author Winkelbauer, H.
dc.contributor.author Cordova-Rodriguez, K.
dc.contributor.author Reyes-Macaya, D.
dc.contributor.author Scott, J.
dc.contributor.author Glock, N.
dc.contributor.author Lu, Z.
dc.contributor.author Hamilton, E.
dc.contributor.author Chenery, S.
dc.contributor.author Holdship, P.
dc.contributor.author Dormon, C.
dc.contributor.author Hoogakker, B.
dc.date.accessioned 2021-12-12T20:24:54Z
dc.date.available 2021-12-12T20:24:54Z
dc.date.issued 2021
dc.identifier.uri https://hdl.handle.net/20.500.12866/10202
dc.description.abstract Planktic and benthic foraminiferal iodine (I) to calcium (Ca) molar ratios have been proposed as an exciting new proxy to assess subsurface and bottom water oxygenation in the past. Compared to trace metals, the analysis of iodine in foraminiferal calcite is more challenging, as iodine is volatile in acid solution. Here, we compare previous analyses that use tertiary amine with alternative analyses using tetramethylammonium hydroxide (TMAH) and ammonium hydroxide (NH4OH) to stabilize iodine in solution. In addition, we assess the effect of sample size and cleaning on planktic and benthic foraminiferal I/Ca. Our stabilization experiments with TMAH and NH4OH show similar trends as those using tertiary amine, giving relatively low I/Ca ratios for planktic and benthic foraminifera samples from poorly oxygenated waters, and high ratios for well-oxygenated waters. This suggests that both alternative methods are suitable to stabilize iodine initially dissolved in acid. Samples that contain 5–10 specimens show a wide spread in I/Ca. Samples containing 20 specimens or more show more centered I/Ca values, indicating that a larger sample size is more representative of the average planktic foraminifera community. The impact of cleaning on planktic and benthic foraminifera I/Ca ratios is very similar to Mg/Ca, with the largest effect occurring during the clay removal step. The largest iodine contaminations were recorded at locations characterized by moderate to high organic carbon contents. In those circumstances, we recommend doubling the oxidative cleaning steps (4 instead of 2 repetitions) to ensure that all organic material is removed en_US
dc.language.iso eng
dc.publisher Wiley
dc.relation.ispartofseries Geochemistry, Geophysics, Geosystems
dc.rights info:eu-repo/semantics/restrictedAccess
dc.rights.uri https://creativecommons.org/licenses/by-nc-nd/4.0/deed.es
dc.subject Amines en_US
dc.subject Ammonia en_US
dc.subject Ammonium hydroxide en_US
dc.subject Benthic and planktic foraminifer I/calcium en_US
dc.subject benthic and planktic foraminifera I/Ca en_US
dc.subject benthic foraminifera en_US
dc.subject Benthic foraminifera en_US
dc.subject calcite en_US
dc.subject Calcite en_US
dc.subject calcium en_US
dc.subject Calcium en_US
dc.subject Calcium carbonate en_US
dc.subject Cleaning en_US
dc.subject cleaning method en_US
dc.subject Cleaning methods en_US
dc.subject environmental samples (Foraminifera) en_US
dc.subject Foraminifera en_US
dc.subject Foraminifers en_US
dc.subject iodine en_US
dc.subject iodine stabilization en_US
dc.subject Iodine stabilization en_US
dc.subject Molar ratio en_US
dc.subject Organic carbon en_US
dc.subject oxygenation en_US
dc.subject Planktic foraminifera en_US
dc.subject planktonic foraminifera en_US
dc.subject Sample sizes en_US
dc.subject Stabilization en_US
dc.subject Tertiary amine en_US
dc.subject Tetramethyl ammonium hydroxide en_US
dc.subject Trace elements en_US
dc.subject trace metal en_US
dc.title Foraminifera Iodine to Calcium Ratios: Approach and Cleaning en_US
dc.type info:eu-repo/semantics/article
dc.identifier.doi https://doi.org/10.1029/2021GC009811
dc.relation.issn 1525-2027


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