Shipments out-of clean air isotopes within the water people from Drake Passing together with Southern Atlantic

Centered on Schmidt (1999) SCHMIDT GA, BIGG GR and you will ROHLING EJ

In oceanic regions with a positive E-P (Evaporation-Precipitation) balance, there is enrichment in the superficial ocean layer due to preferential evaporation of the lighter species ( Meredith MEREDITH MP, GROSE KE, MCDONAGH EL, HEYWOOD KJ, FREW RD and DENNIS PF. 1999. J Geophys Res Oceans (1978–2012) 104(C9): 20949-20962. et al. 1999). On the other hand, river discharges, high precipitation and ice melting are related to regions with depleted values of ? 18 O_sw ( Redfield REDFIELD AC and FRIEDMAN I. 1965. Factors affecting the distribution of deuterium in the ocean. In Symposium on Marine Geochemistry. Rhode Island University Narragansett Marine Laboratory Occasional Publication, Vol. 3, p. 149-168. and Friedman 1965). On a geologic time scale, the glacial boundary conditions influence the isotopic composition of the oceans due to the storage of lighter ? 18 O and ?D isotopes in the ice sheets, which is known as global ice volume effect. However, during interglacial periods, this effect was reversed (Holloway et al. 2015).

Because salinity and ? 18 O_sw are controlled by the same processes, they show a quasi-linear relationship, and the slope is dependent on the kinetic processes acting in the water mass formation area. 2015. Differences among subtropical surface salinity patterns. Oceanogr 28(1): 32-39. 1965). 1999. Global Seawater Oxygen-18 Database – v1.21. , the global mixing line between ? 18 O_sw and salinity can be used as an approximation only in mid to high latitudes, since the scatter for the tropical samples could be up to 0.13‰. Therefore, regional mixing lines become essential pieces in paleoclimatic studies in the equatorial and tropical regions. Holloway et al. (2015) suggested that regions with marked variability in the evaporation-precipitation budget and strong oceanographic dynamics need additional constraints to establish good salinity and ? 18 O_sw relationships on spatial and temporal scales. On the other hand, South Atlantic, Indian and Tropical Pacific Oceans have more reliable paleosalinity reconstructions without the need of additional constraints.

Despite the importance of the Southwest Atlantic Ocean for thermohaline circulation and the global climate through in the South Atlantic Meridional Overturning Circulation (SAMOC), only a few studies have been carried out in this area using stable isotopes. For example, GEOSECS was conducted in the South Atlantic focusing on open waters (Kroopnick 1980, Ostlund OSTLUND HG, CRAIG H, https://datingranking.net/es/omgchat-review BROECKER WS and SPENCER D. 1987. GEOSECS Atlantic, Pacific and Indian ocean expeditions, shorebased data and graphics, Vol. 7. Technical report, I.D.O.E. National Science Foundation, p. 200. et al. 1987) and an independent work of Pierre et al. (1991) focused on a small offshore area of the southwestern Atlantic. None of these papers were focused on paleoclimatic applications. The aim of the present study was to investigate the distribution of the stable isotopes (? 18 O_sw and ?D_sw) at the Western Tropical South Atlantic border, from the continental shelf to slope, in order to better understand the main fractionation processes of these isotopes and establish a regional salinity and ? 18 O_sw relationship to improve paleoceanographic knowledge in the study region.

Following, following the liquid size sinks, the partnership remains steady about drinking water size existence (Craig and you can Gordon GORDON AL, GIULIVI CF, BUSECKE J and you may BINGHAM FM

The fresh new east Brazilian continental margin is common because of its smaller width and superficial deepness when compared with the rest of your own Southwest Atlantic margin, due to low continental erosion price while the short area of marine sedimentation. At exactly the same time, the constant presence of your own Brazil Most recent streaming into the southwestern synchronous with the shelf while the North Brazil Current flowing equatorward hauling enjoying and you will saline Exotic H2o gives the area a fundamentally oligotrophic reputation, and that lowers brand new genesis out-of biogenic situation that define most of your own sedimentary soles throughout the southeastern Brazilian continental shelf ( Knoppers KNOPPERS B, EKAU W and you will FIGUEIREDO AG. 1999. Brand new coast and you will shelf out of eastern and you may northeast Brazil and you can issue transportation. Geo-Aquatic Lett 19: 171. et al. 1999). The fresh new bifurcation of the Southern area Equatorial Latest (SEC) happen at about 10°–14°S near the epidermis as well as the continental shelf width differs from 42 kilometer off Maceio to 8 kilometres away from Salvador, which have on average 31 kilometres ( Fig. 1).