The behavior of dissolved uranium in groundwaters of the Morro do Ferro thorium deposit, Brazil

Groundwater samples were collected for several months in boreholes drilled at Morro do Ferro, a thorium and rare earth deposit located on the Poços de Caldas Plateau, Minas Gerais State, Brazil. An aquifer system has developed in the weathered mantle due to in situ intense alteration. The weathered zone includes a thick argillaceous laterite greater than 100 m thick. The U content and 324U/238U activity ratio were measured in the groundwater samples and in spoil samples of a borehole drilled in the ore body. Some possible mechanisms related to the mobilization of uranium are considered such as complexation with humic substances and adsorption by clays. © 1989.

Microhyla laterite sp nov., A New Species of Microhyla Tschudi, 1838 (Amphibia: Anura: Microhylidae) from a Laterite Rock Formation in South West India

In recent times, several new species of amphibians have been described from India. Many of these discoveries are from biodiversity hotspots or from within protected areas. We undertook amphibian surveys in human dominated landscapes outside of protected areas in south western region of India between years 2013-2015. We encountered a new species of Microhyla which is described here as Microhyla laterite sp. nov. It was delimited using molecular, morphometric and bioacoustics comparisons. Microhyla laterite sp. nov. appears to be restricted to areas of the West coast of India dominated by laterite rock formations. The laterite rock formations date as far back as the Cretaceous-Tertiary boundary and are considered to be wastelands in-spite of their intriguing geological history. We identify knowledge gaps in our understanding of the genus Microhyla from the Indian subcontinent and suggest ways to bridge them.

Laterite as a disinfectant.

A groundwater programme monitoring flow and quality of a potable water spring in a slum district in Kampala, Uganda revealed that although latrines acted as the principal means of organic waste disposal for the 1000 plus people living in the spring’s catchment, levels of faecal indicator bacteria (TVC 45 Deg C) in spring discharge remained at or below detection during the dry season, despite the presence of high levels of chloride (45mg/l-56mg/l) and nitrate (23mg/l – 30mg/l NO3-N), indicating sewage impacts. A programme of column and batch testing of laterite underlying the area provided a means of investigating the soil’s attenuation capacity under more controlled conditions.
X-ray diffraction analyses revealed the laterite to be dominated by quartz and kaolinite with minor (<5% by volume) quantities of haematite. Batch studies revealed that over 99% of bacteriophage adsorbed to haematite in less than 5 minutes. By contrast batch tests on haematite-free soil samples from the Blue Hills in Australia showed that although they had comparable dominant mineralogy and iron coverage on their surfaces (determined from Energy dispersive X-ray fluorescence) they had negligible ability to adsorb H40/1.
Based on the results of the batch studies using natural soils, a programme of batch studies, undertaken using pure haematite showed the mineral to have an extremely high capacity to adsorb bacteriophage, and suggested that it was responsible for the levels of attenuation observed.
The results of column studies were in keeping with the findings of batch experiments. Injection of 20 pore volumes of 300 pfu/mL of the bacteriophage H40/1 into a 20mm diameter glass column packed with sand sized (Ø>500µm) laterite revealed that the column could irreversibly remove over 2.5 log10 bacteriophage over its 10cm length.
Importance:
Mineralogical and batch test data provide convincing evidence to show that laterite can potentially act as an inexpensive means of removing micro organisms from water. The material, particularly in nodular form, displays considerable potential to act as an alternative filter material to conventional quartz filter sands.

Local materials for building houses: laterite valorization in Africa

This paper presents the preliminary results of geological and geomechanical studies on the laterite stone exploited at Dano quarry in Burkina Faso. The field work described the geological structure of quarry sites and their environment to determine the rocks alteration and the links between the bedrock and lateritic material. Physic-mechanical properties have been studied for assessing the potentiality of this material for lightweight housing, to be completed with thermal and environmental considerations. Some social and economic evaluations are in progress in order to foster its utilization under local conditions.

Local materials for building houses: Laterite valorization in Africa

This paper presents the preliminary results of geological and geomechanical studies on the laterite stone exploited at Dano quarry in Burkina Faso. The field work described the geological structure of quarry sites and their environment to determine the rocks alteration and the links between the bedrock and lateritic material. Physic-mechanical properties have been studied for assessing the potentiality of this material for lightweight housing, to be completed with thermal and environmental considerations. Some social and economic evaluations are in progress in order to foster its utilization under local conditions. © (2014) Trans Tech Publications, Switzerland.

Hygrothermal Features of Laterite Dimension Stones for Sub-Saharan Residential Building Construction

The building sector is widely recognized as having a major impact on sustainable development. Both in developed and developing countries, sustainability in buildings approaches are growing. Laterite dimension stone (LDS) is a building material that was traditionally used in sub-Saharan Africa, but its technical features still need to be assessed. This article presents some results of a study focused on the characterization of LDS exploited in Burkina Faso for building purposes. The measured average thermal conductivity is 0.51  W/mK, which increases with water content and evolves with the specific gravity and with porosity. Rock mineral phases (quartz, goethite, hematite, magnetite) are cemented by kaolinite. The porosity of the material is high (30%), with macropores visible on the surface and found in the rock inner structure as well. Results from the hygrothermal monitoring of a pilot building are also presented.

Phosphorus Adsorption onto an Industrial Acidified Laterite By‒Product: Equilibrium and Thermodynamic Investigation

The present research investigates the uptake of phosphate ions from aqueous solutions using acidified laterite (ALS), a by-product from the production of ferric aluminium sulfate using laterite. Phosphate adsorption experiments were performed in batch systems to determine the amount of phosphate adsorbed as a function of solution pH, adsorbent dosage and thermodynamic parameters per fixed P concentration. Kinetic studies were also carried out to study the effect of adsorbent particle sizes. The maximum removal capacity of ALS observed at pH 5 was 3.68 mg P g^-1. It was found that as the adsorbent dosage increases, the equilibrium pH decreases, so an adsorbent dosage of 1.0 g L^-1 of ALS was selected. Adsorption capacity (q_m) calculated from the Langmuir isotherm was found to be 2.73 mg g^-1. Kinetic experimental data were mathematically well described using the pseudo first-order model over the full range of the adsorbent particle size. The adsorption reactions were endothermic, and the process of adsorption was favoured at high temperature; the ΔG and ΔH values implied that the main adsorption mechanism of P onto ALS is physisorption. The desorption studies indicated the need to consider a NaOH 0.1M solution as an optimal solution for practical regeneration applications.

Deciphering the weathering processes using environmental mineralogy and geochemistry: Towards an integrated model of laterite and podzol genesis in the Upper Amazon Basin

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)