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Abstract: Sediments of the Lagoa Vermelha (Red Lake), situated in the Ribeira Valley, southeastern Brazil, are made of a homogeneous, organic-rich, black clay with no visible sedimentary structures. The inorganic geochemical record (Al, As, Ba, Br, Co,Cs, Cr, Fe, Mn, Ni, Rb, Sc, Sb, V, Zn, Hg and Pb) of the lake sediments was analyzed in a core spanning 2430 years. The largest temporal changes in trace metal contents occurred approximately within the last 180 years. Recent sediments were found to be enriched in Pb, Zn, Hg, Ni, Mn, Br and Sb (more than 2-fold increase with respect to the “natural background level”). The enhanced accumulation of Br, Sb, and Mn was attributed to biogeochemical processes and diagenesis. On the other hand, the anomalous concentrations of Pb, Zn, Hg and Ni were attributed to pollution. As Lagoa Vermelha is located in a relatively pristine area, far removed from direct contamination sources, the increased metal contents of surface sediments most likely resulted from atmospheric fallout. Stable Pb isotopes provided additional evidence for anthropogenic contamination. The shift of 206Pb/207Pb ratios toward decreasing values in the increasingly younger sediments is consistent with an increasing contribution of airborne anthropogenic lead. In the uppermost sediments (0–10 cm), the lowest values of the 206Pb/207Pb ratios may reflect the influence of the less radiogenic Pb from the Ribeira Valley District ores (206Pb/207Pb between 1.04 and 1.10), emitted during the last 50 years. [Copyright &y& Elsevier]

The Atlantic Rainforest, covering the area from northern Espirito Santo to Southern Bahia states, has been considered as a stable forest during Pleistocene Glacial times. Aside from modelling and phylogenetic studies, this hypothesis has never been tested with empirical, fossil pollen, paleo-vegetation data. By using palynology, radiocarbon dating, and carbon and nitrogen elemental and isotopic analyses of organic matter, we reconstructed the vegetation dynamics and inferred climatic changes since the Late Pleistocene in the centre of this global biodiversity hotspot. Our results show that the forest biome was resilient to Last Glacial Maximum - LGM conditions, but that the floristic composition differed from that of today. Since the late glacial, the floristic composition of the dense forest changed from cold- to warm-adapted taxa. Structural, as well as floristic, changes occurred during drier conditions of the early and middle Holocene, with an opening of the forest, providing insights into the type of vegetation impacts that might be expected under predicted future drought. • The humid and dense tropical forest biome known as historically stable refuge, was stable during LGM. • Dry mid-Holocene have affected the forest composition as the high presence of C 4 plants occurred during this period. • The pollen assemblage found nowadays compared to the Pleistocene is not analogue. • The dense forest was stable, but the floristics has changed, with maintenance of ancient and inclusion of new species. [ABSTRACT FROM AUTHOR]

Due to the many factors controlling δ13C values in stalagmites, complicating their paleoclimatic and paleoenvironmental interpretation, most studies do not present δ13C values, but instead focus mainly on δ18O values. This is also the case for most cave studies from tropical South America, where many new δ18O stalagmite records covering the last millennia were recently published. Here, we review the δ13C values in stalagmites, investigating the influence on this proxy of local hydroclimate, altitude, temperature and vegetation types, by employing a new dataset composed of published and unpublished carbon isotope records from various sites in tropical South America. The main factors influencing δ13C values are associated with the local hydroclimate, followed by minor effects from temperature. Most of the isotopic records show a significant correlation between the δ13C and δ18O values, indicating a close relationship between local hydroclimate and atmospheric convective processes related to the South American Monsoon System. • δ13C values in stalagmites from tropics are related with local hydrology. • Prior calcite precipitation is the main driver for δ13C values in stalagmites. • The mean conditions of local hydroclimate are associated with South American monsoon. • Dataset of δ13C values in stalagmites is useful as paleoclimate record. [ABSTRACT FROM AUTHOR]