Long-Term (∼57 ka) Controls on Mercury Accumulation in the Souther Hemisphere Reconstructed Using a Peat Record from Pinheiro Mire (Minas Gerais, Brazil)

Abstract

Natural archives have been used to reconstruct mercury atmospheric deposition at different spatial and temporal scales during the Holocene in the Northern Hemisphere. In this study, we present the results from a Brazilian mountain mire (Pinheiro mire, Minas Gerais, SE Brazil), extending back to ∼57 ka. The core was analyzed for mercury concentration, organic matter content, organic carbon isotopic composition, and tracers of mineral matter flux. Principal components analysis followed by principal components regression enabled us to determine the evolution of the weight of the latent processes governing the accumulation of mercury through time. We show that climate change was the main driver for the variations of mercury concentrations, either indirectly by (i) enhancing soil erosion in the mire's catchment, which led to a decrease in mercury concentration due to dilution by low mercury-containing mineral matter, (ii) increasing regional dust deposition, which resulted in increased concentrations, or directly, by long-term changes in atmospheric wet deposition (arid vs humid periods). Internal peat processes (i.e., decomposition and mass loss) had a minor influence at the time scale represented by the core.

Prediction of Holocene Mercury Accumulation Trends by Combining Palynological and Geochemical Records of Lake Sediments (Black Forest, Germany)

“…The main advantage of using component scores rather than the original geochemical data in the regression analysis is that the rotated components represent new synthetic orthogonal variables, and the effects of these components within the regression analysis are additive. The record of the regression weights of the components with depth/time was used to evaluate the chronological variations of the controls on the Hg record [51]. All statistical calculations were performed within the statistic environment of R-version 3.3.3 [52].…”

Prediction of Holocene Mercury Accumulation Trends by Combining Palynological and Geochemical Records of Lake Sediments (Black Forest, Germany)

“…The main advantage of using component scores rather than the original geochemical data in the regression analysis is that the rotated components represent new synthetic orthogonal variables, and the effects of these components within the regression analysis are additive. The record of the regression weights of the components with depth/time was used to evaluate the chronological variations of the controls on the Hg record [50]. All statistical calculations were performed within the statistic environment of R -version 3.3.3 [51].…”

The Role of Climate: 71 ka of Atmospheric Mercury Deposition in the Southern Hemisphere Recorded by Rano Aroi Mire, Easter Island (Chile)

“…In this work, we found that three of the four main processes controlling Hg concentration depended on climate: wet and dry Hg deposition (rainfall and dustfall, respectively), as well as local catchment soil erosion owing to precipitation events [29]. The effect of long-term peat decomposition, the only autogenic process identified, was confined to the Holocene section of the peat [29].…”

“…In a recent work, we studied Hg accumulation in Pinheiros (18 • S, 43 • W) [29], a Pleistocene age (last~57 ka) tropical mire located in a valley in Serra do Espinhaço Meridional (state of Minas Gerais, Brazil). In this work, we found that three of the four main processes controlling Hg concentration depended on climate: wet and dry Hg deposition (rainfall and dustfall, respectively), as well as local catchment soil erosion owing to precipitation events [29]. The effect of long-term peat decomposition, the only autogenic process identified, was confined to the Holocene section of the peat [29].…”