Distribution away from fresh air isotopes within the water masses off Drake Passage and the Southern Atlantic

Distribution away from fresh air isotopes within the water masses off Drake Passage and the Southern Atlantic

According to Schmidt (1999) SCHMIDT GA, BIGG GR and 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 Osw ( 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 Osw 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 Osw 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 Osw 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 aplicaciones de citas talkwithstranger focusing on open waters (Kroopnick 1980, Ostlund OSTLUND HG, CRAIG H, 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 Osw and ?Dsw) 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 Osw relationship to improve paleoceanographic knowledge in the study region.

Next, following the drinking water bulk sinks, the relationship stays stable on the drinking water size life (Craig and you may Gordon GORDON AL, GIULIVI CF, BUSECKE J and you may BINGHAM FM

The fresh new eastern Brazilian continental margin is typical for the quicker depth and you can shallow deepness when compared to other areas of Southwestern Atlantic margin, due to low continental erosion price therefore the brief section of marine sedimentation. Simultaneously, the ceaseless exposure of the Brazil Most recent moving towards southwestern parallel on shelf and also the Northern Brazil Current moving equatorward transporting enjoying and you will saline Warm H2o offers the area a fundamentally oligotrophic profile, and that reduces brand new genesis out of biogenic topic that make up most of the sedimentary bottoms regarding the southeastern Brazilian continental shelf ( Knoppers KNOPPERS B, EKAU W and you may FIGUEIREDO AG. 1999. The coast and you will shelf of eastern and northeast Brazil and thing transportation. Geo-Marine Lett 19: 171. et al. 1999). This new bifurcation of your Southern area Equatorial Most recent (SEC) occurs at about ten°–14°S near the body in addition to continental bookshelf thickness differs from 42 kilometer out of Maceio to eight kilometres out of Salvador, which have an average of 30 km ( Fig. 1).



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