Browsing by Author "Dall�Agnol, Roberto"

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Bioavailability of copper and nickel in naturally metal-enriched soils of Caraj�s Mining Province, Eastern Amazon, Brazil
(Springer Science and Business Media Deutschland GmbH, 2021-04-09T00:00:00) Martins, Gabriel Caixeta; da Silva Junior, Ediu Carlos; Ramos, S�lvio Junio; Maurity, Cl�vis Wagner; Sahoo, Prafulla Kumar; Dall�Agnol, Roberto; Guilherme, Luiz Roberto Guimar�es
Naturally elevated contents of copper (Cu) and nickel (Ni) are found in soils worldwide, and their potential toxicity is better understood when geochemical reactive fractions are identified and monitored. Thus, this study aimed to assess the bioavailability of Cu and Ni and estimate environmental risks in naturally metal-enriched soils of Caraj�s Mining Province, Eastern Amazon, Brazil. For that, 58 surficial soil samples were analyzed for their extractable contents of Cu and Ni by Mehlich 1. Next, 13 soil samples were selected for additional single and sequential extractions, for the determination of metal content in the shoots of grasses naturally growing in these soils and for calculating the risk assessment code. Despite the naturally high total concentrations, the contents of easily available Cu and Ni are a minor fraction of total concentrations (up to 10.15%), and the reducible oxide and residual pools hold the major proportion of total content of metals. This contributed to low bioavailability, low environmental risk, and also to low concentrations of these metals on grasses collected in the field. Soil organic matter, Fe2O3, Al2O3 and clay content have a dominant role in metals retention on studied soils. Our findings on the bioavailability of Cu and Ni in a region of great economic relevance for Brazil are important not only for predicting the elements� behavior in the soil�plant system but also for refining risk assessments and to provide useful data for environmental quality monitoring. � 2021, The Author(s), under exclusive licence to Springer Nature Switzerland AG.
Landscape and Climate Changes in Southeastern Amazonia from Quaternary Records of Upland Lakes
(MDPI, 2023-03-27T00:00:00) Guimar�es, Jos� Tasso Felix; Sahoo, Prafulla Kumar; e Souza-Filho, Pedro Walfir Martins; da Silva, Marcio Sousa; Rodrigues, Tarc�sio Magevski; da Silva, Edilson Freitas; Reis, Luiza Santos; de Figueiredo, Mariana Maha Jana Costa; Lopes, Karen da Silva; Moraes, Aline Mamede; Leite, Alessandro Sab�; da Silva J�nior, Renato Oliveira; Salom�o, Gabriel Negreiros; Dall�Agnol, Roberto
The upland lakes (ULs) in Caraj�s, southeastern Amazonia, have been extensively studied with respect to their high-resolution structural geology, geomorphology, stratigraphy, multielement and isotope geochemistry, palynology and limnology. These studies have generated large multiproxy datasets, which were integrated in this review to explain the formation and evolution of the ULs. These ULs evolved during the Pliocene�Pleistocene periods through several episodes of a subsidence of the lateritic crust (canga) promoted by fault reactivation. The resulting ULs were filled under wet/dry and warm/cool paleoclimatic conditions during the Pleistocene period. The multielement geochemical signature indicates that the detrital sediments of these ULs were predominantly derived from weathered canga and ferruginous soils, while the sedimentary organic matter came from autochthonous (siliceous sponge spicules, algae, macrophytes) and allochthonous (C3/C4 canga and forest plants and freshwater dissolved organic carbon) sources. Modern pollen rain suggests that even small ULs can record both the influence of canga vegetation and forest signals; thus, they can serve as reliable sites to provide a record of vegetation history. The integrated data from the sedimentary cores indicate that the active ULs have never dried up during the last 50 ka cal BP. However, subaerial exposure occurred in filled ULs, such as the Tarzan mountain range during the Last Glacial Maximum (LGM) and the Boca�na and S11 mountain ranges in the mid-Holocene period, due to the drier conditions. Considering the organic proxies, the expansion of C4 plants has been observed in the S11 and Tarzan ULs during dry events. Extensive precipitation of siderite in UL deposits during the LGM indicated drier paleoenvironmental conditions, interrupting the predominantly wet conditions. However, there is no evidence of widespread forest replacement by savanna in the Caraj�s plateau of southeastern Amazonia during the late Pleistocene and Holocene. � 2023 by the authors.
Methodological approach and general guidelines to geochemical mapping and background-baseline analysis for environmental assessment: a case study in the Caraj�s Mineral Province, Brazil
(Sociedade Brasileira de Geologia, 2023-01-09T00:00:00) Souza-Filho, Pedro Walfir Martins; Sahoo, Prafulla Kumar; da Silva, Marcio Sousa; Dall�Agnol, Roberto; Filho, Carlos Augusto Medeiros; Leite, Alessandro Sab�; da Silva Ferreira J�nior, Jair; da Rocha Nascimento, Wilson; da Silva e Silva, G�ssica; Salom�o, Gabriel Negreiros; Sarracini, Fabiana; Junior, Renato Oliveira Silva; da Costa, Marlene Furtado
We present this manuscript as a methodological approach and general guidelines for geochemical mapping and background/baseline projects for environmental assessment in tropical areas. A case study was carried out in the Itacai�nas River watershed (IRW), Eastern Amazon, to fill in a gap in knowledge on the distribution of chemical elements, particularly those potentially toxic, in the near-surface environment of the area. The high-impact results of this research project revealed the need for similar scientific investigation across the globe with the implementation of a systematic methodology. The study shows, for example, the importance of well-planned field activities, multi-medium sampling, analytical methods, laboratory procedures, database construction, and general aspects of data processing and statistical treatment. The importance of this contribution is that it can be used as a reference in support of geospatial analysis in research within the scope of geochemical mapping and background-baseline projects. The database is accessible through a web-based geographic information system front-end; a Geochemical Atlas of the IRW will be available as soon as possible. � 2022 The authors.
Source Apportionment of Chemical Elements and Their Geochemical Baseline Values in Surface Water of the Parauapebas River Basin, Southeast Amazon, Brazil
(MDPI, 2022-12-09T00:00:00) Quaresma, Leandro Silva; Silva, Gessica da Silva e; Sahoo, Prafulla Kumar; Salom�o, Gabriel Negreiros; Dall�Agnol, Roberto
The present work aims to evaluate the chemical quality and establish the geochemical baseline values of elements in the surface waters of the Parauapebas River basin (PRB), which is one of the major subbasins in the Itacai�nas River watershed (IRW) located in the Brazilian Amazon. A total of 327 surface water samples were collected during the rainy and dry seasons in 2017. Results indicate that waters are slightly acidic to alkaline (pH 6 to 8), and there was a strong influence of the seasonal variation on water quality, with higher values of turbidity, Fe, Al, Mn, TDS, etc. in the rainy season. Two geochemical baseline types for the PRB were defined, i.e., �conservative baseline� (CB), represented by the cumulative frequency curve, and the �environmental baseline� (EB), comprising the sum of natural and diffuse anthropogenic contributions, represented by the 98th percentile. Except Fe, Mn and Al, the CB and EB values of various trace elements (Ba, Co, Cr, Cu, Ni, Rb, Sn, Sr, Ti, V and Zn) were lower than the recommended limits of CONAMA 357/05�class 2. The principal component analysis (PCA) identified the major geochemical association (Al-Ti-Cu-Cr-Ni-V), which is an imprint of the local geological setting. Ni and Cr showed enrichment at sites where mafic and ultramafic rocks are concentrated, while Cu concentration is mainly associated with the north and south mineralization belts. High concentrations of Fe and Mn are characteristic of the waters of this region and this is mostly influenced by specific land use activities and intense weathering/erosion of catchment materials. At the upper Parauapebas, anthropogenic contributions associated with soil use and occupation were also important along with the geogenic effects. The obtained results regarding sources of contaminants in some microbasins can be taken as a starting point for future studies on the environmental quality of the region�s water resources. � 2022 by the authors.