Weathering and clay formation in semi-arid calcareous soils from Northeastern Brazil

Oliveira, Daniel Pereira de; Sartor, Lucas Resmini; Júnior, V. S. Souza; Corrêa, Marcelo Metri; Romero, Ricardo Espíndola; Andrade, Gabriel Ramatis Pugliese; Ferreira, Tiago Osório

doi:10.1016/j.catena.2017.10.030

Cited by 31 publications

(10 citation statements)

References 35 publications

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“…Differences in kaolinite and illite content between Anyuan and Longnan are not only related to the composition of the parent rock. The sampling depth and topography also have a significant impact on the clay mineral and soil formation [45]. Samples from Anyuan County came from average elevations of between 311 and 468 m, with relatively gentle relief (gradient: 24 • -25 • ) and dense vegetation cover.…”

Section: Soil Particle Size and Distribution Of Clay Minerals In Ree Mining Areasmentioning

confidence: 99%

Grain Size Distribution and Clay Mineral Distinction of Rare Earth Ore through Different Methods

et al. 2020

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Although clay mineral content in ion-absorbed rare earth ores is crucial for migrating and releasing rare earth elements, the formation, distribution, and migration of clay minerals in supergene rare earth ores have not been fully understood. Therefore, this study analyzes the characteristics of clay mineral type and content, soil particle size, pH value, leaching solution concentration, and leaching rate. This analysis was performed using different methods, such as regional rare earth mine soil surveys, in situ leaching profile monitoring, and indoor simulated leaching. The results showed that the grain size and volume curve of rare earth ore have unimodal and bimodal shapes, respectively. X-ray diffraction showed the differences in clay mineral types formed by different weathered bedrocks. The principal clay minerals were kaolinite, illite, chlorite, and vermiculite, with their relative abundance varying with parent rock lithology (granite and low-grade metamorphic rocks). In the Ganxian granite weathering profile, the kaolinite content increased from top to bottom. The decomposition of feldspar minerals to kaolinite was enhanced with an increase in the SiO2 content during weathering. The in situ leaching profile analysis showed that the kaolinite content increased initially and then decreased, whereas the illite/mica content exhibited the opposite trend. Under stable leaching solution concentration and leaching rate, clay mineral formation is favored by lower pH. Low pH, low leaching rate, and highly-concentrated leaching solution (12 wt%) resulted in a slow increase in kaolinite content in the upper part of the profile (30 cm). A lower concentration of the leaching solution (4 wt%) resulted in rapid enrichment of kaolinite after 15 days. Low pH, leaching solution concentration, and leaching rate promoted the formation of distinct kaolinite horizons. We suggest that by disregarding other control factors, rare earth recovery of over 90% can be achieved through leach mining with solutions of 8 wt% and a pH of 5 at a leaching rate of 5 mL/min.

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Section: Soil Particle Size and Distribution Of Clay Minerals In Ree Mining Areasmentioning

confidence: 99%

Grain Size Distribution and Clay Mineral Distinction of Rare Earth Ore through Different Methods

et al. 2020

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“…Sua distribuição é irregular em alguns perfi s no compartimento dfv, como em P4, P8, P9 e P10. Esses dois elementos garantem valores muito altos de saturação por bases (> 90%), atribuindo aos solos generalizadamente um caráter hipereutrófi co, condizente com outros estudos realizados por Oliveira et al (1998); Naime et al (2007); Ferreira et al (2016); Oliveira et al (2018), entre outros, em solos do semiárido.…”

Section: Propriedades Químicas Dos Solosunclassified

Solos Carbonáticos E a Desertificação No Médio Curso Da Bacia Do Rio Salitre, Bahia

Rios

Carvalho

Oliveira

2020

Rev. Bras. Geomorfol.

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das terras, na qual a deterioração persistente dos solos e a destruição das caatingas constituem expressões marcantes. Condicionantes locais, como a crescente exposição de solos, pode constituir fator que amplia os riscos de desertificação. Este estudo analisou as relações entre os solos carbonáticose uma possível desertificação em curso na bacia do rio Salitre, no semiárido seco da Bahia. O estudo foi realizado tendo como recorte os dois compartimentos de relevo que caracterizam a área de estudo, denominados platô carbonático e depressão de fundo de vale. Foram utilizadas técnicas de sensoriamento remoto para delimitação temporal da exposição dos solos, comparando os anos de 1950 e 2019. A distribuição da cobertura pedológica numa vertente perpassando os dois compartimentos foi analisada para dimensionar a organização morfológica dos solos, que também foram caracterizados em laboratório a partir de suas propriedades físicas e químicas (com destaque para o conteúdo de carbonato de cálcio equivalente). Os resultados apontaram que na área do platô carbonático há maior cobertura vegetal e os solos são, do ponto de vista pedogenético, mais evoluídos, mais estáveis e mais resistentes à erosão. Já na depressão de fundo de vale, há quase 70% de solo exposto (crescente nas últimas décadas) sobre condições morfogenéticas bastante instáveis, com forte remoção do solum e sobre materiais altamente friáveis, de elevada alcalinidade e teores de carbonato de cálcio equivalente que superam 500 g kg-1. Estas condições trazem implicações que dificultam a recuperação das caatingas na área da depressão, revelando uma persistente e evolutiva exposição dos solos, que sugere um quadro de alto risco de desertificação.

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“…In addition to these climatic factors that drastically affect the Brazilian semiarid, impacting directly on the socioeconomic conditions of the populations of this region, the soils of this area in the majority do not present great agricultural aptitude from the physical point of view, since they are young soils in the pedogenetic perspective , low weathered soils with low effective depth and low moisture retention capacity in the profile, influencing the local floristic composition and making subsistence farming difficult due to the nonirrigated agriculture (Montenegro and Montenegro, 2012;Oliveira et al, 2018).…”

Section: Literature Review Characterization Of the Environmentmentioning

confidence: 99%

The application of agrometeorological techniques contributes to the agricultural resilience of forage cactus: A review

Alves¹,

Jardim²,

Souza³

et al. 2018

Amaz. Jour. of Plant Resear.

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The Brazilian semi-arid is an area that has a strong influence on climatic factors and agricultural vulnerability, which govern the availability and supply of fodder. The understanding of the limitations and the alternatives to be adopted, aid in the improvement of the systems of production of fodder and an increase in the benefits of the system. In this review, we sought to address agrometeorological aspects and agronomic techniques aimed at improving resilience in forage cactus production systems under different cropping systems in arid and semi-arid environments through information on the stability of the plant population contributing to reducing the risk environmental degradation and production losses.

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Weathering and clay formation in semi-arid calcareous soils from Northeastern Brazil

Cited by 31 publications

References 35 publications

Grain Size Distribution and Clay Mineral Distinction of Rare Earth Ore through Different Methods

Grain Size Distribution and Clay Mineral Distinction of Rare Earth Ore through Different Methods

Solos Carbonáticos E a Desertificação No Médio Curso Da Bacia Do Rio Salitre, Bahia

The application of agrometeorological techniques contributes to the agricultural resilience of forage cactus: A review

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