SALINITY: ? 18 Osw Evaluations To help you PALEOCEANOGRAPHIC RECONSTRUCTIONS

To validate the results obtained in our study, we compared the current Salinity: ? 18 O_sw ratio found by this study along with the primary data of Pierre and Ostlund, and the equation used by Toledo et al. (2007), which estimates the sea surface salinity based on the oxygen isotope composition of Globigerinoides ruber (white). All of these works are based on data from the upper Southwest Atlantic Ocean (<250 m). Toledo et al. (2007) used an equation obtained from previous data available from NASA/GISS (also using data from Pierre et al. (1991) and Ostlund et al. (1987), among others), converted from PBD (Pee Dee Belemnite) to V-SMOW using the -0.27 factor ( Hut HUT G. 1987. Consultants Group Meeting on Stable Isotopes Reference Samples for geochemical and hydrological investigations. Report to Director General. International Atomic Energy Agency, Vienna, 42 p. 1987):

That it collection range possess a mountain most around the Meteoric Water line (MWL:?=8) (Craig 1961), and therefore means the common dating ranging from hydrogen and you can oxygen isotope percentages for the pure seas

In order to compare our ? 18 O_sw and T-S data in the regional context with literature, ? 18 O_sw data available in the NASA/GISS Global Seawater Oxygen-18 Database (Schmidt et al. 1999) from the South Atlantic Ocean (Pierre et al. 1991, Ostlund et al. 1987) were used. As explained in the introduction, the study by Pierre et al. (1991) was conducted in a narrow area between 21.9°S and 26.5°S latitude during the austral Summer, from pling from surface to

2000) near 21°S together with kept analysis of body samples merely along side GEOSECS section (Fig. 1). Thereafter, these functions could be known since Pierre and you may Ostlund, correspondingly.

Although recent isotopic data on the southeast Brazilian coast have been published by Venancio et al. (2014), this dataset is not comparable because it refers to a coastal upwelling area under the influence of different continental and internal processes. All ? 18 O_sw, ?D_sw and salinity data presented here will be submitted to NASA/GISS to improve the coverage of isotopic data for the South Atlantic Ocean.

Stable ISOTOPES Delivery And you will FRACTIONATION Designs

Hydrographic investigation and you will isotopic viewpoints for each sample are sumples was basically broke up by-water mass depending on the big sum acquired after this new mixing triangle analyses. That it dataset is an excellent icon of isotopic straight distribution up to 2000 m breadth, and you will try well-distributed involving the h2o public (a total of 34 TW products, 21 SACW products, 18 AAIW products and you may 20 NADW examples, apart from the five CW trials).

Following the well-established ?D_sw and ? 18 O_sw linear relationship (Merlivat and Jouzel 1979), we found at the surface layer a moderate correlation (R?= 0.55, n=27), and at the intermediate and deeper layer, a stronger correlation (R?=0.94 and 0.81; n= 33 and 38, respectively). The ? 18 O_sw:?D_sw relationship for the whole dataset is presented in Figure 2 with a strong linear correlation (R 2 =0.94, n=98), which indicates that all of the future considerations regarding the ? 18 O_sw can be extrapolated to ?D_sw including the Salinity and ? 18 O_sw relationship.

Because the slopes and intersection points for each of the layers were very similar (?=7.05, 7.02 and 6.91; b= -0.49, -0.67 and -1.4, respectively), we propose a mixing line gathering together the entire dataset (?D_sw= 7.62* ? 18 O_sw – 1.18) ( Fig. 2).

Following the Salinity and ? 18 O_sw relationship, the vertical ? 18 O_sw profile has a similar pattern to salinity ( Fig. 3). The upper layer, corresponding to TW, is characterized by a maximum with values up to 1.34‰ and controlled mainly by the E-P balance (Craig and Gordon 1965). Along the SACW layer, there is a consistent depletion of this isotope from 1.13‰ at 180 m to 0.19‰ at 700 m. This behavior follows the temperature and salinity profile tendency in the thermocline. The ? 18 O_sw minimum is associated with the positioning of AAIW, which is characterized by minimum salinity derived from the sea melt and high precipitation rates in the Antarctic Divergence region (Tomczak and Godfrey 2003), which reduces the levels of ? 18 O_sw (up to -0.33‰). Below 1000 m depth, a slight increase of the ? 18 O_sw and salinity levels associated with the NADW layer can be observed.