Differences between mono-generic and mixed diatom silicon isotope compositions trace present and past nutrient utilisation off Peru
| dc.contributor.author | DOERING, Kristin | |
| dc.contributor.author | EHLERT, Claudia | |
| hal.structure.identifier | Helmholtz Centre for Ocean Research [Kiel] [GEOMAR] | |
| dc.contributor.author | GRASSE, Patricia | |
| hal.structure.identifier | Environnements et Paléoenvironnements OCéaniques [EPOC] | |
| dc.contributor.author | CROSTA, Xavier | |
| hal.structure.identifier | Environnements et Paléoenvironnements OCéaniques [EPOC] | |
| dc.contributor.author | FLEURY, Sophie | |
| hal.structure.identifier | Rheinisch-Westfälische Technische Hochschule Aachen University [RWTH] | |
| dc.contributor.author | FRANK, Martin | |
| hal.structure.identifier | Institute of Geosciences [Kiel] | |
| dc.contributor.author | SCHNEIDER, Ralph | |
| dc.date.accessioned | 2024-05-15T12:17:16Z | |
| dc.date.available | 2024-05-15T12:17:16Z | |
| dc.date.issued | 2016-03 | |
| dc.identifier.issn | 0016-7037 | |
| dc.identifier.uri | https://oskar-bordeaux.fr/handle/20.500.12278/199877 | |
| dc.description.abstractEn | In this study we combine for the first time silicon (Si) isotope compositions of small mixed diatom species (d 30 Si bSiO2) and of large handpicked mono-generic (i.e. genus = Coscinodiscus) diatom samples (d 30 Si Coscino) with diatom assemblages extracted from marine sediments in the Peruvian upwelling region in order to constrain present and past silicate utilisation. The extension of a previous core-top data set from the Peruvian shelf demonstrates that d 30 Si Coscino values record near-complete Si utilisation, as these are similar to the isotopic composition of the subsurface source waters feeding the upwelling. In contrast, the d 30 Si bSiO2 of small mixed diatom species increase southward along the shelf as well as towards the shore. We attribute highest d 30 Si bSiO2 values partly to transient iron limitation but primarily to the gradual increase of Si isotope frac-tionation within the seasonal diatom succession, which are mainly recorded by small diatom species during intense bloom events. In contrast, lower d 30 Si bSiO2 values are related to initial Si isotope utilisation during periods of weak upwelling, when low Si(OH) 4 concentrations do not permit intense blooms and small diatom species record substantially lower d 30 Si signatures. As such, we propose that the intensity of the upwelling can be deduced from the offset between d 30 Si bSiO2 and d 30 Si Coscino (D 30 Si coscino-bSiO2), which is low for strong upwelling conditions and high for prevailing weak upwelling. We apply the information extracted from surface sediments to generate a record of the present-day main upwelling region covering the past 17,700 years and find that this location has also been characterized by a persistent offset (D 30 Si coscino-bSiO2). By comparison with the diatom assemblages we show that the coastal upwelling system changed markedly between weak and strong upwelling conditions. In addition, our model calculations to quantify species-specific Si isotope fractionation effects based on the diatom assemblages indicate an overall minor influence that cannot explain the high amplitude in the measured d 30 Si bSiO2 record. | |
| dc.language.iso | en | |
| dc.publisher | Elsevier | |
| dc.title.en | Differences between mono-generic and mixed diatom silicon isotope compositions trace present and past nutrient utilisation off Peru | |
| dc.type | Article de revue | en_US |
| dc.identifier.doi | 10.1016/j.gca.2015.12.029 | |
| dc.subject.hal | Planète et Univers [physics]/Océan, Atmosphère | |
| dc.subject.hal | Planète et Univers [physics]/Sciences de la Terre/Océanographie | |
| dc.subject.hal | Planète et Univers [physics]/Sciences de la Terre/Climatologie | |
| bordeaux.journal | Geochimica et Cosmochimica Acta | en_US |
| bordeaux.page | 30-47 | |
| bordeaux.volume | 177 | |
| bordeaux.hal.laboratories | EPOC : Environnements et Paléoenvironnements Océaniques et Continentaux - UMR 5805 | en_US |
| bordeaux.institution | Université de Bordeaux | |
| bordeaux.institution | CNRS | |
| bordeaux.peerReviewed | oui | |
| bordeaux.import.source | hal | |
| hal.identifier | hal-02105550 | |
| hal.version | 1 | |
| hal.popular | non | |
| hal.audience | Internationale | |
| hal.export | false | |
| workflow.import.source | hal | |
| dc.rights.cc | Pas de Licence CC | en_US |
| bordeaux.COinS | ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.jtitle=Geochimica%20et%20Cosmochimica%20Acta&rft.date=2016-03&rft.volume=177&rft.spage=30-47&rft.epage=30-47&rft.eissn=0016-7037&rft.issn=0016-7037&rft.au=DOERING,%20Kristin&EHLERT,%20Claudia&GRASSE,%20Patricia&CROSTA,%20Xavier&FLEURY,%20Sophie&rft.genre=article |
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