@InProceedings{GonçalvesDiVeLeMuMaLu:2019:MiChBe,
               author = "Gon{\c{c}}alves, Caio Souza and Dias, Bruna B. and Venancio, Igor 
                         Martins and Lessa, Douglas Villela de Oliveira and Mulitza, Stefan 
                         and Mackensen, Andreas and Luiza, Albuquerque Ana",
          affiliation = "{Universidade Federal Fluminense (UFF)} and {Universidade Federal 
                         Fluminense (UFF)} and {Instituto Nacional de Pesquisas Espaciais 
                         (INPE)} and {Universidade Federal Fluminense (UFF)} and 
                         {University of Bremen} and {Alfred Wegner Institute for Polar and 
                         Marine Research} and {Universidade Federal Fluminense (UFF)}",
                title = "Millennial-Scale Changes in Benthic Foraminifera Stable Carbon 
                         Isotope Gradients in the Western Equatorial Atlantic",
                 year = "2019",
         organization = "AGU Fall Meeting",
             abstract = "The stable carbon isotope ratio of benthic foraminifera 
                         (\δ13C) is a widely applied proxy for ocean circulation and 
                         productivity changes, as the \δ13C gradient between some 
                         species is linked to carbon export and bottom water oxygen 
                         concentration. Although there is some consensus about what could 
                         drive the variability of the oxygen concentration (such as the 
                         ocean circulation or the export of primary productivity), the 
                         mechanisms, especially in the Western Equatorial Atlantic (WEA), 
                         remain unexplained. To explore potential factors influencing 
                         bottom water [O2] over the last glacial period (63 to 29 kyr) in 
                         more detail, we analyzed the \δ13C difference between three 
                         benthic foraminiferal species (Cibicides wuellerstorfi, Uvigerina 
                         peregrina, and Globobulimina affinis) from a site in the WEA. Our 
                         records demonstrate that the most prominent decreases in oxygen 
                         diffusion occurred during the Heinrich Stadials (HS) (especially 
                         HS3 and HS4) as a result of a reduced North Atlantic Deep Water 
                         (NADW) ventilation and increased fluvial terrigenous input. Our 
                         results show decreases in the strength of the bottom-water 
                         currents during these events, reflected by decreases in the 
                         sortable silt grain-size fraction (SS). Moreover, we show that the 
                         highest values of total organic carbon content (TOC) at our site 
                         during HS did not result from increased surface primary 
                         productivity but rather from continental input via the 
                         Parna{\'{\i}}ba River. Furthermore, the highest TOC values are 
                         inconsistent with the gradient between two benthic foraminifera 
                         species (U. peregrina and C. wuellerstorfi), which reflects the 
                         low flux of labile organic carbon in the sediment. We suggest that 
                         the deposition and accumulation of terrigenous material reduced O2 
                         diffusion into the sediment and, coupled with millennial-scale 
                         ventilation, played an important role in influencing the oxygen 
                         availability in the WEA during several HS over the last 
                         glaciation.",
  conference-location = "San Francisco, CA",
      conference-year = "09-13 dec.",
             language = "en",
           targetfile = "goncalves_millenial.pdf",
        urlaccessdate = "26 abr. 2024"
}