Mercury deposition on the western tropical South Atlantic during the last glacial-interglacial cycle

• Ano de defesa: 2024
• Autor(a) principal: Almeida, Bernardo Sartori Chede Rosauro de
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Palavras-chave em Português: Mercury; Atlantic meridional overturning circulation; Marine sediments; Glacial-interglacial changes; Millennial-scale events; Western tropical South Atlantic; Mercúrio em sedimento; Ciclo biogeoquímico; Paleoclimatologia; Oceano Atlântico Sul; Mudança climática; Deposição atmosférica; Mudanças glaciais-interglaciais; Mercúrio; Sedimento marinho; Eventos milenares; Circulação meridional de capotamento do Atlântico; Oeste tropical do Atlântico Sul
• Link de acesso: https://app.uff.br/riuff/handle/1/35691

Mercury (Hg) is released via natural and anthropogenic sources. Atmospheric deposition via dry and wet deposition is the main source of Hg to the continents and oceans. Organic matter (OM) is the primary driver of Hg accumulation in marine sediments. Previous studies reported that Hg is sensitive to past climate changes and that global and regional climatic factors can control its environmental dynamics. Here, we used sediment core M125-95-3 collected at the western tropical South Atlantic to investigate Hg deposition and accumulation changes in the marine realm over the last 70 ka. Our records show higher concentration during the glacial period than in the interglacial period probably due to increased atmospheric dust. On millennial-scale events, the increased residence time of North Atlantic Deep Water (NADW) enhanced the regenerative scavenging of Hg, which reduced Hg concentration in M125-95-3 core. In addition, the dilution effect might have reduced the Hg concentration further during Heinrich stadials (HS) due to increased terrigenous input via the São Francisco River. Altogether, the results suggest a strong influence of deep ocean circulation on the deposition and accumulation of Hg in marine sediments in the western tropical South Atlantic on millennial timescales, highlighting long-term oceanic processes that act on the geochemical cycle of Hg.