Porous space in Brazilian soils using X-ray computed tomography

Abstract

A porosidade é importante na determinação da qualidade de um solo, por possuir forte influência na aeração, na transferência de água/solutos/gases/calor, na resistência à penetração e ramificação de raízes, além do desenvolvimento de microorganismos. A avaliação do espaço poroso, considerando vazios intra e interagregados, em diferentes tipos de solo e suas implicações (vantagens/desvantagens) é objetivo deste estudo. Foi determinada a porosidade inter e intra-agregados em solos dos tipos Latossolo Vermelho distrófico e Neossolo Regolítico eutrófico. Para os intra-agregados foram classificados: o tamanho, a forma e a inclinação. A porosidade inter-agregados foi maior para o Neossolo; este é um comportamento esperado para um solo arenoso, quando comparado a um solo argiloso. Considerando a porosidade intra-agregados, destacou-se a predominância da inclinação horizontal, poros maiores e maior quantidade de poros complexos para o Neossolo. A aplicação de microtomografia computadorizada de raios-X se mostrou eficiente na caracterização micromorfológica da porosidade do solo. Palavras-chave: Porosidade, Imagem digital, Agregado. Porous space in Brazilian soils using X-ray computed tomography A B S T R A C TPorosity is important in determining the quality of the soil, as it has strong influence on the aeration, in the transfer of water/solute/gas/heat, resistance to penetration and branching roots, and the development of microorganisms. The assessment of the pore space, whereas intra and inter-empty clusters in different soil types and their implications (advantages/disadvantages) is aim of this study. It was determined to inter-and intra-aggregate porosity in soil types Red Latossol distrophic. For intra-aggregates were classified: the size, shape and slope. The inter-aggregate porosity was higher for Regossols; this is expected behavior for a sandy soil, compared to a clay soil. Considering the intra-aggregate porosity, noted the predominance of horizontal slope, larger pores and a larger number of complex pores to Regossols. The application of computed microtomography X-ray proved effective in micromorphological characterization of soil porosity.

X-ray computed microtomography in the evaluation of the porous system of soils

“…3 L-type voids were considered as inter-aggregate voids, while voids classified as M and P were considered as the intraaggregate voids (Costa et al, 2016). Intra-aggregates were classified according to shape, size and inclination.…”

“…A variability threshold coefficient of 20% was adopted for voxel intensity, in comparison to the mean, considering as pure those with intensity within the following interval [m -1s, m + 1s] (Costa et al, 2016). These limits were adopted to locate a multimodal histogram, which can be modeled as a mixture of Gaussians.…”

“…Due to the limited processing capacity of this plug-in to identify and label the many voids existing in one tomographic image of soil, three ranges of size were used: small (S) (≤ 8 voxels), medium (M) (< 8 and ≥ 100.000 voxels) and large (L) (> 100,000 voxels) (Costa et al, 2016).…”

Production of Synthetic Carbonate Rocks Using Limestone Mining Waste: Mineralogical, Petrophysical and Geomechanical Characterization

“…Evaluating the pores observed along the sample, it is reported that the interconnected pore volume promotes fluid flow permeability along the structure, as it allows fluid transmission between pores. Although porosity estimation by image analysis generated by computed microtomography has the advantage of being a non-destructive verification [20], pores smaller than the image voxel size (55 µm) were not identified and were no quantified in the total pore volume, being a limitation of this methodology [36]. This graph shows the porosity distribution profile (%) and the slice position along the length of the sample, where 0 on the horizontal axis indicates the center portion of the rock.…”