@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",
targetfile = "fadina_effects.pdf",
urlaccessdate = "19 abr. 2024"
}