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Oxygen and hydrogen isotope signatures of Northeast Atlantic water masses

dc.contributor.authorVoelker, Antje
dc.contributor.authorColman, Alber
dc.contributor.authorOlack, Gerard
dc.contributor.authorWaniek, Joanna J.
dc.contributor.authorHodell, David
dc.date.accessioned2020-07-24T08:57:12Z
dc.date.available2020-07-24T08:57:12Z
dc.date.issued2015-06
dc.date.updated2020-07-23T16:00:21Z
dc.description.abstractOnly a few studies have examined the variation of oxygen and hydrogen isotopes of seawater in NE Atlantic water masses, and data are especially sparse for intermediate and deep-water masses. The current study greatly expands this record with 527 δ18O values from 47 stations located throughout the mid- to low-latitude NE Atlantic. In addition, δD was analyzed in the 192 samples collected along the GEOTRACES North Atlantic Transect GA03 (GA03_e = KN199-4) and the 115 Iberia-Forams cruise samples from the western and southern Iberian margin. An intercomparison study between the two stable isotope measurement techniques (cavity ring-down laser spectroscopy and magnetic-sector isotope ratio mass spectrometry) used to analyze GA03_e samples reveals relatively good agreement for both hydrogen and oxygen isotope ratios. The surface (0-100 m) and central (100-500 m) water isotope data show the typical, evaporation related trend of increasing values equatorward with the exception for the zonal transect off Cape Blanc, NW Africa. Off Cape Blanc, surface water isotope signatures are modified by the upwelling of fresher Antarctic Intermediate Water (AAIW) that generally has isotopic values of 0.0 to 0.5‰ for δ18O and 0 to 2‰ for δD. Along the Iberian margin the Mediterranean Outflow Water (MOW) is clearly distinguished by its high δ18O (0.5-1.1‰) and δD (3-6‰) values that can be traced into the open Atlantic. Isotopic values in the NE Atlantic Deep Water (NEADW) are relatively low (δ18O: –0.1 to 0.5‰; δD: –1 to 4‰) and show a broader range than observed previously in the northern and southern convection areas. The NEADW is best observed at GA03_e Stations 5 and 7 in the central NE Atlantic basin. Antarctic Bottom Water isotope values are relatively high indicating modification of the original Antarctic source water along the flow path. The reconstructed δ18O-salinity relationship for the complete data set has a slope of 0.51, i.e. slightly steeper than the 0.46 described previously by Pierre et al. (1994) for the tropical to subtropical Northeast Atlantic. This slope decreases to 0.46 for the subtropical North Atlantic Central Water (NACW) and the MOW and to 0.32 for the surface waters of the upper 50 m. The δD-salinity mixing lines have estimated slopes of 3.01 for the complete data, 1.26 for the MOW, 3.47 for the NACW, and 2.63 for the surface waters. The slopes of the δ18O-δD relationship are significantly lower than the one for the Global Meteoric Water Line with 5.6 for the complete data set, 2.30 for the MOW, 4.79 for the NACW, and 3.99 for the surface waters. The lower slopes in all the relationships clearly reflect the impact of the evaporation surplus in the subtropics.pt_PT
dc.description.sponsorshipEC Grant agreement n° 228344 - EUROFLEETS, C2007-FCT/319/2006pt_PT
dc.description.versioninfo:eu-repo/semantics/publishedVersionpt_PT
dc.identifier.doi10.1016/j.dsr2.2014.11.006pt_PT
dc.identifier.issn0967-0645
dc.identifier.slugcv-prod-423445
dc.identifier.urihttp://hdl.handle.net/10400.1/14136
dc.language.isoengpt_PT
dc.peerreviewedyespt_PT
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/pt_PT
dc.subjectStable isotopespt_PT
dc.subjectNorth Atlanticpt_PT
dc.subjectSeawater samplespt_PT
dc.subjectGeotracespt_PT
dc.subjectOxygen isotopespt_PT
dc.subjectDeuteriumpt_PT
dc.subjectWater mass signalspt_PT
dc.titleOxygen and hydrogen isotope signatures of Northeast Atlantic water massespt_PT
dc.typejournal article
dspace.entity.typePublication
oaire.citation.endPage106pt_PT
oaire.citation.startPage89pt_PT
oaire.citation.titleDeep Sea Research Part II: Topical Studies in Oceanographypt_PT
oaire.citation.volume116pt_PT
person.familyNameVoelker
person.givenNameAntje
person.identifier2315310
person.identifier.ciencia-idC11E-D8E6-CDFA
person.identifier.orcid0000-0001-6465-6023
person.identifier.ridC-5427-2012
person.identifier.scopus-author-id8784446000
rcaap.cv.cienciaidC11E-D8E6-CDFA | Antje Helga Luise Voelker
rcaap.rightsopenAccesspt_PT
rcaap.typearticlept_PT
relation.isAuthorOfPublicationbca80a86-eb35-4bca-a4ba-85b53831d69e
relation.isAuthorOfPublication.latestForDiscoverybca80a86-eb35-4bca-a4ba-85b53831d69e

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