Salinity and stable oxygen isotope relationship in the Southwestern Atlantic: constraints to paleoclimate reconstructions

Stable isotopes have been widely used in the literature both to discuss current ocean circulation processes, as well as to reconstitute paleoceanographic parameters. The distribution of oxygen and deuterium stable isotopes in seawater (δ18Osw and δDsw) at the Western Tropical South Atlantic border w...

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Bibliographic Details
Published in:	Anais da Academia Brasileira de Ciências Vol. 91; no. 3; p. e20180226
Main Authors:	BELEM, ANDRE L., CARICCHIO, CAMILLA, ALBUQUERQUE, ANA LUIZA S., VENANCIO, IGOR M., ZUCCHI, MARIA DO R., SANTOS, TARCIO HENRIQUE R. DOS, ALVAREZ, YACI GALLO
Format:	Journal Article
Language:	English
Published:	Academia Brasileira de Ciências 2019
Subjects:	MULTIDISCIPLINARY SCIENCES oxygen 18 paleosalinity seawater isotopic composition southwestern Atlantic stable isotopes stable isotopes seawater isotopic composition paleosalinity oxygen 18 southwestern Atlantic
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Summary:	Stable isotopes have been widely used in the literature both to discuss current ocean circulation processes, as well as to reconstitute paleoceanographic parameters. The distribution of oxygen and deuterium stable isotopes in seawater (δ18Osw and δDsw) at the Western Tropical South Atlantic border was investigated to better understand the main fractionation processes of these isotopes and establish a regional salinity and δ18Osw relation to improve the paleoceanographic knowledge in the region. This study was conducted during a quasi-synoptic oceanographic cruise in which 98 discrete seawater samples were collected in the core of the main water masses for stable isotope analysis. A strong correlation between δ18Osw and δD was found, which made it possible to extrapolate the results for δ18Osw to δD. Although it was not possible to distinguish the water masses based only on their isotopic signatures, the water masses had a strong salinity and δ18Osw relation, and compared with previous studies, a seasonal pattern was observed. Paleosalinity differences of up to 0.2 psu between Summer and Winter are reported. Considering the limitations of the current techniques to seasonally separate the samples for the paleoceanographic studies, an intermediate Mixing Line for the Tropical South Atlantic (SSS = 1.942* δ18Osw + 34.56) was proposed to reduce the estimated errors associated with these seasonal variations.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0001-3765 1678-2690 1678-2690
DOI:	10.1590/0001-3765201920180226