Fechar
Metadados

@InProceedings{FadinaVBLSSBSA:2019:EfLoCl,
               author = "Fadina, Omotayo Anuoluwapo Fadina and Venancio, Igor Martins and 
                         Bel{\'e}m, Andr{\'e} Luiz and Lessa, Douglas Villela de Oliveira 
                         and Silveira, Carla Semiramis and Santos, Thiago Pereira dos and 
                         Bertagnolli, Denise and Silva Filho, Emmanoel Vieira and 
                         Albuquerque, Ana Luiza",
          affiliation = "{Universidade Federal Fluminense (UFF)} and {Instituto Nacional de 
                         Pesquisas Espaciais (INPE)} and {Universidade Federal Fluminense 
                         (UFF)} and {Universidade Federal Fluminense (UFF)} and 
                         {Universidade Federal Fluminense (UFF)} and {Universidade Federal 
                         Fluminense (UFF)} and {Universidade Federal Fluminense (UFF)} and 
                         {Universidade Federal Fluminense (UFF)} and {Universidade Federal 
                         Fluminense (UFF)}",
                title = "Effects of long-term climate changes and geochemical processes on 
                         mercury accumulation on South American and African margins during 
                         the last glacial/interglacial cycle",
                 year = "2019",
         organization = "AGU Fall Meeting",
             abstract = "Marine sediments from the Western and Eastern South Atlantic 
                         continental margins are used to reconstruct mercury (Hg) 
                         accumulation over the last glacial/interglacial cycle. Sediment 
                         core GL-1248, collected from the continental slope off 
                         northeastern Brazil, and sediment core ODP1077, retrieved from the 
                         Congo deep-sea fan area, both dated to the last 128 ka and 130 ka 
                         respectively. Mercury concentrations in GL-1248 ranged between 
                         14.95 and 69.43ng/g, and varied with periodicities of 56 ka and 
                         900 yr suggesting the presence of glacial-interglacial changes and 
                         millennial-scale variability respectively. Parallel trends of Hg 
                         and XRF-Fe plots suggest that following atmospheric Hg deposition 
                         onto the continent, Hg is incorporated with iron (Fe) minerals 
                         before transportation and eventual immobilization at the NE Brazil 
                         continental slope. Mercury concentrations in ODP1077 varied 
                         significantly, having concentrations between 23.12 ng/g and 256 
                         ng/g, and its plot exhibits an anti-phase pattern with the Fe/Ca 
                         ratio plot, that distinguishes between periods of increased and 
                         decreased terrigenous material delivery. This inverse trend in the 
                         plots of mercury concentration and Fe/Ca ratio shows that during 
                         periods of increased (decreased) terrigenous material delivery, 
                         less (more) mercury accumulates in the marine sediment. Although 
                         Hg concentration is poorly correlated with total organic carbon 
                         (TOC), it correlates positively with XRF-Ca implying that marine 
                         organic matter played a significant role in mercury distribution 
                         and accumulation in the ODP1077 marine sediment core. Despite the 
                         fact that both marine sediment cores were retrieved from the 
                         tropics and cover the same glacial/interglacial periods, their 
                         mercury variations and the main drivers of mercury accumulations 
                         are dissimilar. Accordingly, we identified two different pathways 
                         by which mercury is incorporated into marine sediments for 
                         prolonged storage and inclusion in the global mercury 
                         biogeochemical cycle. The outcome of this study suggests that 
                         regional climate processes and geochemical conditions are 
                         essential to Hg variations in environmental archives. Another 
                         obvious finding is that the source of sedimentary organic carbon 
                         is a key determinant of their affinity for mercury.",
  conference-location = "San Francisco, CA",
      conference-year = "09-13 dec.",
             language = "en",
        urlaccessdate = "23 jan. 2021"
}


Fechar