The great geological and soil variation in the state of Minas Gerais, Brazil, indicates the need for regional studies to understand the geochemical background of soils. The Rio Doce Basin became a priority area for geochemical background determination after the rupture of the tailings dam of Fundão in 2015. In this context, the objectives of this study were to propose Reference Values of Soil Quality in the Rio Doce Basin, to define variables that can predict metal(loid) concentrations in the soil, and to examine the correlation between metal(loid) concentrations determined by X-ray fluorescence and by the traditional method. One hundred and seven samples were collected from minimally disturbed areas, representing the main soils and source materials. Metal(loid)s were determined by acid digestion and X-ray fluorescence. Descriptive statistics of the data, as well as the calculation of the Randomized Dependence Coefficient (RDC) and Principal Component Analysis (PCA) were carried out. The soils were found to be acidic, dystrophic with low Mehlich-1 extracted P contents, and have a variable texture. The coefficient of determination ranged from 0.4 to 0.9, suggesting X-ray fluorescence as a promising technique for determining metal(loid) concentrations in soils. The absence of correlation between clay and organic matter contents with metal(loid) concentrations suggests that the latter were inherited exclusively from the parent material, with little influence of pedogenesis. Metal mineralization in the highlands that constitute the topographic drainage divide of the basin increase the reference values of soil quality to higher values than established for the State of Minas Gerais.
RESUMO O uso da pirólise como forma de aproveitamento energético da biomassa e resíduos orgânicos vem sendo avaliada como uma alternativa aos combustíveis fósseis. O carvão gerado neste processo é altamente recalcitrante, e sua incorporação ao solo pode contribuir para o sequestro de carbono, além de também melhorar a qualidade do solo de uso agrícola. Este trabalho avaliou o efeito de diferentes condições de pirólise sobre as características físicas, como resistência mecânica, densidade e rendimento gravimétrico do carvão produzido. Para isso, amostras de madeira de Eucalyptus cloeziana foram pirolisadas em nove temperaturas entre 300 e 700 °C, sob três taxas de aquecimento (5, 22,5 e 40 °C min-1). A produção de líquido pirolenhoso atinge o máximo de rendimento em temperaturas entre de 400 e 700 °C na taxa de aquecimento de 5 °C.min-1. Com o aumento da temperatura e da taxa de aquecimento, aumenta a ocorrência de rupturas na estrutura dos carvões, com consequente redução da resistência física destes. Palavras-chave: carbono; estabilidade térmica; energia. Influence of temperature and heating rates on mechanical resistance, density and yield of the wood charcoal of Eucalyptus cloeziana ABSTRACT The use of pyrolysis as a way of energetic use of biomass and organic wastes has been evaluated as an alternative to fossil fuels. The carbon generated in this process is highly recalcitrant, and its incorporation into the soil can contribute to the carbon sequestration, as well as improving soil quality for agricultural use. This work evaluated the effect of different pyrolysis conditions on the physical characteristics, such as mechanical strength, density and gravimetric yield of the charcoal produced. For this, samples of Eucalyptus cloeziana wood were pyrolyzed at nine temperatures between 300 and 700 ° C, under three heating rates (5, 22.5 and 40 ° C min-1). The production of pyrolignal liquid reaches the maximum yield at temperatures between 400 and 700 ° C with heating rate of 5 ° C min-1. With the increase of temperature and the rate of heating, it increases the occurrence of ruptures in the structure of the charcoals, with consequent reduction of their physical resistance.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.