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All publications of “Luiz Roberto Guimarães Guilherme”

16 results

Assessment of Trace Element Contents in Soils and Water from Cerrado Wetlands, Triângulo Mineiro Region

Bruno Teixeira Ribeiro ORCID logo , Diogo Costa Nascimento, Nilton Curi, Luiz Roberto Guimarães Guilherme, Enio Tarso de Souza Costa, Guilherme Lopes, [...]


ABSTRACT In the Brazilian Cerrado biome, there are wetlands locally known as “Veredas”, which are swampy plains between hills and rivers. Since the 1970’s, the Cerrado biome has been gradually converted to livestock, crop, or forestry production. Until now, very few studies were conducted to evaluate the baseline contents of trace elements in Cerrado wetland soils. Due to their position in the landscape (bottom lands), the wetlands are potentially susceptible to contamination by runoff and/or leaching from surrounding areas at […]

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Maria Aparecida Pereira Pierangeli, Luiz Roberto Guimarães Guilherme, Geila Santos Carvalho, Camila de Andrade Carvalho, Carlos Alberto Silva, Luiza Maria Pereira Pierangeli


Total Reflection X-ray Fluorescence (TXRF) is a promising technique for analysis of trace elements (TEs), mainly because samples do not need to be digested, thereby reducing generation of waste and emission of toxic fumes. This study compared the levels of the TEs:Cr, Mn, Ni, Zn, Cu, As, Se, Hg, and Pb in soil samples collected from intensive agricultural and native vegetation areas, as determined by TXRF and by flame or graphite furnace atomic absorption spectrometry (FAAS/GFAAS). In addition, we compared […]


Vanessa Martins, Douglas Ramos Guelfi Silva, Giuliano Marchi, Maurício Cunha Almeida Leite, Éder de Souza Martins, Ana Stella Freire Gonçalves, [...]


The current high price of potassium chloride and the dependence of Brazil on imported materials to supply the domestic demand call for studies evaluating the efficiency of alternative sources of nutrients. The aim of this work was to evaluate the effect of silicate rock powder and a manganese mining by-product, and secondary materials originated from these two materials, on soil chemical properties and on brachiaria production. This greenhouse experiment was conducted in pots with 5 kg of soil (Latossolo Vermelho-Amarelo […]

Arsenate and cadmium content in soils of the cerrado bioma

Mari Lucia Campos, Luiz Roberto Guimarães Guilherme, João José Granate de Sá e Melo Marques, Nilton Curi, Alessandra Siqueira Antunes Araújo, David José Miquelluti, [...]


Knowledge on As and Cd levels in soils is important to monitor the entry of these elements into the food chain from anthropogenic sources. The purpose of this study was to determine the natural content of As and Cd in representative soils of the Cerrado region, Brazil. Soil samples were collected from three sub-regions: G (eastern Goiás), T (Triângulo Mineiro) and N (northeastern MG). To determine the soil levels of As and Cd, samples were digested by acid attack in […]

Replication of an IVG protocol to estimate bioaccessible arsenic in materials from a gold mining area in Brazil

Fábio Benedito Ono, Luiz Roberto Guimarães Guilherme, Leandro Antunes Mendes, Geila Santos Carvalho


Tests for bioaccessibility are useful in human health risk assessment. No research data with the objective of determining bioaccessible arsenic (As) in areas affected by gold mining and smelting activities have been published so far in Brazil. Samples were collected from four areas: a private natural land reserve of Cerrado; mine tailings; overburden; and refuse from gold smelting of a mining company in Paracatu, Minas Gerais. The total, bioaccessible and Mehlich-1-extractable As levels were determined. Based on the reproducibility and […]

Characterization and nutrient release from silicate rocks and influence on chemical changes in soil

Douglas Ramos Guelfi Silva, Giuliano Marchi, Carlos Roberto Spehar, Luiz Roberto Guimarães Guilherme, Thomaz Adolpho Rein, Danilo Araújo Soares, [...]


The expansion of Brazilian agriculture has led to a heavy dependence on imported fertilizers to ensure the supply of the growing food demand. This fact has contributed to a growing interest in alternative nutrient sources, such as ground silicate rocks. It is necessary, however, to know the potential of nutrient release and changes these materials can cause in soils. The purpose of this study was to characterize six silicate rocks and evaluate their effects on the chemical properties of treated […]

Soil properties under native vegetation in Minas Gerais, Brazil: distribution by phytophysiognomy, hydrography and spatial variability

Alba Lucia Araujo Skorupa, Luiz Roberto Guimarães Guilherme, Nilton Curi, Charles Plínio de Castro Silva, José Roberto Soares Scolforo, João José Granate de Sá e Melo Marques


One of the factors affecting the distribution of native vegetation is soil formation. Therefore, soils under native vegetation can be highly informative with regard to a region and the original soil fertility, as records of conditions found before agricultural reclamation (agrosilvopasture). The purpose of this study was to assess soil fertility and texture under native vegetation fragments sampled during the Forest Survey of the State of Minas Gerais, Brazil. In general, the variability in all soil properties was high, except […]

Selenium sorption in soils of the cerrado biome

Lívia Botelho de Abreu, Geila Santos Carvalho, Nilton Curi, Luiz Roberto Guimarães Guilherme, João José Granate de Sá e Melo Marques


The study of Se distribution in soils is of general interest because of the narrow range between deficiency and toxicity. The chemical species of Se with the greatest toxicological potential is selenate, due to its high mobility in soils. The study of selenate chemistry is of great importance to understand Se behavior in tropical soils. A batch adsorption experiment was performed using 2 g soil samples in 20 mL of solution with 10 different Se concentrations in the form of […]

Selenate and selenite on yield, mineral nutrition and biofortification with selenium in lettuce cultivars

Sílvio Júnio Ramos, Valdemar Faquin, Hilário Júnior de Almeida, Fabrício William Ávila, Luiz Roberto Guimarães Guilherme, Carla Elisa Alves Bastos, [...]


Selenium is an important antioxidant element associated with physiological processes in plants, microorganisms, animals, and humans. However, its mode of action and essentiality in plants are still disputed. In Brazil, information on Se in agricultural crops is extremely scarce, though there are indications that low levels of Se are being consumed by the population. The objective of this study was to evaluate the effect of selenate and selenite on yield, mineral nutrition and biofortification with Se of lettuce cultivars. The […]

Plant availability of trace elements in sewage sludge-treated soils: methodology

Giuliano Marchi, Luiz Roberto Guimarães Guilherme, Andrew C Chang


Synthetic root exudates were formulated based on the organic acid composition of root exudates derived from the rhizosphere of aseptically grown corn plants, pH of the rhizosphere, and the background chemical matrices of the soil solutions. The synthetic root exudates, which mimic the chemical conditions of the rhizosphere environment where soil-borne metals are dissolved and absorbed by plants, were used to extract metals from sewage-sludge treated soils 16 successive times. The concentrations of Zn, Cd, Ni, Cr, and Cu of […]

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