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Diagenetic production, accumulation and sediment-water exchanges of methylmercury in contrasted sediment facies of Lake Titicaca (Bolivia) ArchiMer
Guédron, S.; Audry, S.; Acha, D.; Bouchet, S.; Point, D.; Condom, T.; Heredia, C.; Campillo, S.; Baya, A.; Groleau, A.; Amice, Erwan; Amouroux, D..
Monomethylmercury (MMHg) concentrations in aquatic biota from Lake Titicaca are elevated although the mercury (Hg) contamination level of the lake is low. The contribution of sediments to the lake MMHg pool remained however unclear. In this work, seven cores representative of the contrasted sediments and aquatic ecotopes of Lake Titicaca were sliced and analyzed for Hg and redox-sensitive elements (Mn, Fe, N and S) speciation in pore-water (PW) and sediment to document early diagenetic processes responsible for MMHg production and accumulation in PW during organic matter (OM) oxidation. The highest MMHg concentrations (up to 12.2 ng L−1 and 90% of THg) were found in subsurface PWs of the carbonate-rich sediments which cover 75% of the small basin and 20%...
Tipo: Text Palavras-chave: Methylmercury; Lake sediment; Early diagenesis; High altitude ecosystem; Diffusive fluxes.
Ano: 2020 URL: https://archimer.ifremer.fr/doc/00615/72735/71843.pdf
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Sporormiella as a tool for detecting the presence of large herbivores in the Neotropics Biota Neotropica
Raczka,Marco Felipe; Bush,Mark B.; Folcik,Alexandra M.; McMichael,Crystal H..
The reliability of using the abundance of Sporormiella spores as a proxy for the presence and abundance of megaherbivores was tested in southern Brazil. Mud-water interface samples from nine lakes, in which cattle-use was categorized as high, medium, or low, were assayed for Sporormiella representation. The sampling design allowed an analysis of both the influence of the number of animals using the shoreline and the distance of the sampling site from the nearest shoreline. Sporormiella was found to be a reliable proxy for the presence of large livestock. The concentration and abundance of spores declined from the edge of the lake toward the center, with the strongest response being in sites with high livestock use. Consistent with prior studies in...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Extinction; Fossil pollen; Lake sediment; Livestock; Pleistocene Megafauna; Sporormiella spores.
Ano: 2016 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1676-06032016000100110
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