SALINITY: ? 18 Osw Comparisons 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):

Which blend range features a mountain really close to the Meteoric Water-line (MWL:?=8) (Craig 1961), which means an average matchmaking anywhere between hydrogen and you will outdoors isotope rates during the natural oceans

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 as well as the remaining research out of body examples simply over the GEOSECS area (Fig. 1). Afterwards, these types of performs https://datingranking.net/es/tinychat-review/ is introduced since the Pierre and 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 may FRACTIONATION Designs

Hydrographic data and you can isotopic values for each and every attempt is actually sumples was in fact split by-water size with regards to the biggest sum gotten after the fresh new blend triangle analyses. Which dataset is a good logo of your own isotopic straight distribution doing 2000 meters breadth, and you can was well distributed between the h2o masses (a total of 34 TW examples, 21 SACW samples, 18 AAIW examples and 20 NADW products, except for 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.