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Differences between mono-generic and mixed diatom silicon isotope compositions trace present and past nutrient utilisation off Peru

dc.contributor.authorDOERING, Kristin
dc.contributor.authorEHLERT, Claudia
hal.structure.identifierHelmholtz Centre for Ocean Research [Kiel] [GEOMAR]
dc.contributor.authorGRASSE, Patricia
hal.structure.identifierEnvironnements et Paléoenvironnements OCéaniques [EPOC]
dc.contributor.authorCROSTA, Xavier
hal.structure.identifierEnvironnements et Paléoenvironnements OCéaniques [EPOC]
dc.contributor.authorFLEURY, Sophie
hal.structure.identifierRheinisch-Westfälische Technische Hochschule Aachen University [RWTH]
dc.contributor.authorFRANK, Martin
hal.structure.identifierInstitute of Geosciences [Kiel]
dc.contributor.authorSCHNEIDER, Ralph
dc.date.accessioned2024-05-15T12:17:16Z
dc.date.available2024-05-15T12:17:16Z
dc.date.issued2016-03
dc.identifier.issn0016-7037
dc.identifier.urihttps://oskar-bordeaux.fr/handle/20.500.12278/199877
dc.description.abstractEnIn 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.isoen
dc.publisherElsevier
dc.title.enDifferences between mono-generic and mixed diatom silicon isotope compositions trace present and past nutrient utilisation off Peru
dc.typeArticle de revueen_US
dc.identifier.doi10.1016/j.gca.2015.12.029
dc.subject.halPlanète et Univers [physics]/Océan, Atmosphère
dc.subject.halPlanète et Univers [physics]/Sciences de la Terre/Océanographie
dc.subject.halPlanète et Univers [physics]/Sciences de la Terre/Climatologie
bordeaux.journalGeochimica et Cosmochimica Actaen_US
bordeaux.page30-47
bordeaux.volume177
bordeaux.hal.laboratoriesEPOC : Environnements et Paléoenvironnements Océaniques et Continentaux - UMR 5805en_US
bordeaux.institutionUniversité de Bordeaux
bordeaux.institutionCNRS
bordeaux.peerReviewedoui
bordeaux.import.sourcehal
hal.identifierhal-02105550
hal.version1
hal.popularnon
hal.audienceInternationale
hal.exportfalse
workflow.import.sourcehal
dc.rights.ccPas de Licence CCen_US
bordeaux.COinSctx_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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