Bauxitic Soils Research Articles

A report on radon emission from bauxitic material in Perth, Manchester, Jamaica

Bauxitic soils in Jamaica are enriched with rare earth elements and other heavy minerals/elements by up to two orders of magnitude relative to bedrock. Geochemical evidence supports the origin of Jamaican bauxite as volcanic ash fall-out from Central America and windblown dust from West Africa. Jamaican bauxite, by virtue of its possible igneous origins, is suspected of being a source of radioactive material. The potential concentration and mobility of radon gas from bauxite waste is an environmental health and safety risk. Therefore, this paper investigates the theoretical radon concentrations and exposure rates in the bauxite mining community in Perth, Manchester. Results from the study show that the exposure rates in the Perth community are all below the recommended 1 WLM/yr. Therefore, radon from the bauxite waste is not a concern for radiation exposure and could be a potential recycled material for brick and other low-income housing materials in Jamaica.

Physiochemical characterization of lateritic bauxite mining soil

Physiochemical characteristics play a significant role in evaluating the engineering behaviour of soil material and its suitability for foundation. Investigation upon the physical and chemical characteristics of lateritic bauxite soils were done on samples collected from three exmining bauxite sites (Bukit Goh, Semambu and Indera Mahkota) in Kuantan District, Pahang, Malaysia. The presence of chemical element was evaluated based on the elemental mineral composition content identified through X-Ray Fluorescence (XRF). The results revealed that Semambu lateritic bauxite soil has the highest content of alumina (Al2O3), 25.54%. The alumina content enrichment is one of the effects from the laterization of bauxite process. In addition, the physical testing included are moisture content, specific gravity and Atterberg Limit. Further investigation on the physical properties of the soil has found that Semambu has the highest MC, 33.27%, but at the same time PI is less than 12%. This is as a key indicator that lateritic bauxite is prone to surface erosion and unsuitable for construction purposes in its natural condition. The risk of the surface erosion and settlement of the ground causes it requires stabilizer that can rapid the curing time. Additionally, the high moisture content is likely to have higher chance to experience liquefaction and causes foundation problem to future infrastructures that may be built in the studied area.

Formation of environmentally persistent free radicals and reactive oxygen species during the thermal treatment of soils contaminated by polycyclic aromatic hydrocarbons

Environmentally persistent free radicals (EPFRs) are emerging contaminants of increasing concern due to their toxicity for life and ecosystems, yet their formation, behavior and fate are poorly known. In particular, there is actually no knowledge on the formation of those radicals during the thermal treatment of soils containing polycyclic aromatic hydrocarbons. Such knowledge is important because thermal treatment is a remediation method used to decontaminate soils by removing and degrading PAHs. Here, we studied the formation of radicals in three types of cultivated soils, bauxite soil, fluvo-aquic soil and chernozem soil, artificially contaminated by benzo[a]pyrene, during thermal treatment from 100 to 200 °C for 1 h, using electron paramagnetic resonance. Results show spins densities of radicals up to of 2.079 × 1017 spins/g for bauxite soil, 1.481 × 1017 spins/g for fluvo-aquic soil and 8.592 × 1016 spins/g for chernozem soil at 175 °C. The formed radicals exhibited multiple decays during their observable time and the shortest 1/e lifetimes of radicals up to 757.58 h. These findings are strengthened by EPFR-induction of reactive oxygen species (ROS), O2·− and ·OH, which increased in concentrations from 100 to 200 °C. Overall, our results demonstrates for the first time that thermal treatment of PAHs-contaminated soils induces the formation of EPFRs and suggests that thermal treatment might not be a fully clean remediation method for soils as thermal treatment creates new contaminants.

High contribution of hydrocarbon transformation during the removal of polycyclic aromatic hydrocarbons from soils, humin and clay by thermal treatment at 100–200 °C

Polycyclic aromatic hydrocarbons (PAHs) are major pollutants in air, soils and sediments. PAH-polluted soils can be cleaned rapidly by thermal treatment. PAH volatilization is considered as the main process explaining PAH removal at low temperature, yet other processes may occur. Particularly, we hypothesize that thermal transformation can also explain PAH removal, where transformation refers to both degradation and formation of bound PAHs. We thus studied the removal of spiked benzo[a]pyrene at 0.5 mg/g in bauxite soil, fluvo-aquic soil, chernozem soil, montmorillonite, humin, and quartz sand as control, from 100 to 200 °C. We measured concentrations of benzo[a]pyrene in the volatilized fraction and solid residues by high-performance liquid chromatography. We identified transformation products by gas chromatography–mass spectrometry. Results show that the contribution of thermal transformation to the removal of benzo[a]pyrene increased from 24.7 to 58.4 wt% for bauxite soil, from 4.4 to 38.2 wt% for fluvo-aquic soil, and from 11.5 to 35.9 wt% for chernozem soil, with temperature increasing from 100 to 200 °C. Transformation such as oxidation occurred in all samples except in benzo[a]pyrene-spiked quartz sands. Transformation of benzo[a]pyrene was thus partly explained by the presence of clay minerals, as evidenced for the montmorillonite assay where transformation contributed 74.6 wt% to the total removal of benzo[a]pyrene at 200 °C. Overall, our findings demonstrate a major overlooked contribution of transformation to PAH removal at low temperature.

Shear Strength Characterization of Bauxite Deposits in Kuantan, East Coast Malaysia

Engineering characterization which are useful for "temperate" zone soils usually fail to predict the field performance of bauxitic soils, because the index tests upon which the characterization are based are not always reproducible for bauxitic soils. Fifteen (15) bauxitic soil of undisturbed and disturbed samples from 3 distinct sites in Kuantan, all derived from basalt parent rock but representing various stages of weathering were subjected to engineering and mineralogic tests. Values for cohesion and friction angles are evaluated. Soils from Semambu has the highest moisture content of 33.27%, the cohesion value is however lower compared to Bukit Goh which has moisture content of 21.74%. Study are further done to discover the relationship with cohesion and friction angles. Thus, by measuring the cohesion and friction angle can evaluate the performance of bauxite shear strength.

Mapping of Aluminous Rich Laterite Depositions through Hyper Spectral Remote Sensing

Increased dimensionality of the satellite data proves to be very useful for discriminating features with very close spectral matching. Present study concentrates on the retrieval of reflectance spectra from the level one radiometrically corrected data in Koraput district (Orissa) for the Bauxite ore. In the present study, atmospheric correction model FLAASH has been used to retrieve reflectance from the radiance data. Preprocessing of the dataset has been done before applying atmospheric correction on the dataset. Spectral subsetting of noise prone bands has been successfully done. Local destriping of the affected bands has been done using a 3*3 local mean filter. Spectral signatures of samples were derived from the processed data. Spectral signature of each sample and derived features vectors were correlated with the satellite image of the area and distribution of each feature was demarcated. Spatial abundance of each feature was used in preparation of mineral abundance map. Accuracy of the map was assessed using training sets of representative geological units. The mineral abundance mapping using the spectral analysis of the reflectance image involves the endmember collection using the N-Dimensional visualizer tool in ENVI software. Laterite, Bauxite, Iron and silica rich Aluminous laterite soil, Alluvium and Forest were selected as the end members after understanding the geology and analysis of the reflectance image. Various mapping techniques were applied to generate the final classified mineral abundance Map, Linear Spectral Unmixing, Mixture Tune Matched Filtering, Spectral Feature Fitting, Spectral Angle Mapper were the techniques used. Results have revealed the ability of Hyper spectral Remote sensing data for the identification and mapping of Hydrothermal altered products like Bauxite, Aluminous Laterite. This technology can be utilized for targeting minerals in the altered zone.

Influence of the geological setting on the REE geochemistry of estuarine sediments: A case study of the Zrmanja River estuary (eastern Adriatic coast)

Increasing use of rare earth elements (REE) in many new technologies results in their increasing presence in the environment and consequently in natural water systems. The Zrmanja River estuary represents a small, semi-closed system located in a karstic landscape of the eastern Adriatic coast characterised by the prevailing red soil (terra rossa) cover, numerous bauxite pits and the proximity of a decommissioned alumina plant, i.e. sources of geomaterials enriched in rare earth elements. To study the influence of such a substrate on estuarine sediment geochemistry, distribution of REEs in the surface sediments of the Zrmanja River estuary and surrounding soils were investigated. Both sediment and soil samples displayed significant variation in terms of REE concentrations as well as their normalised patterns, with overall highest REE levels measured in bauxitic soils (ΣREE 333–596mgkg−1); up to an order of magnitude higher than in other samples. In estuarine sediments, ΣREE ranged from 29.7mgkg−1 to 180mgkg−1, and displayed an increase along the estuary transect. Highest levels of rare earths in sediments of the Zrmanja River were observed in locations closest to the former alumina plant, indicating a transfer of particles rich in REE from the anthropogenically degraded environment in the vicinity of the factory and its influence on the geochemistry of the estuarine sediments. Sediment REE normalised patterns and associated fractionation parameters (ΣLREE/ΣHREE, (La/Nd)NASC, (La/Yb)NASC) showed similarity to those observed for soil samples, confirming a significant influence of local lithological and pedological setting on the sediment REE composition. Moreover, spatial changes in these parameters in sediments clearly followed the changes in nearby soils and can be differentiated on a relatively small scale.

Risk analysis from naturally occurring radioactive materials in the Jamaican terrestrial environment

In this work, statistics and geospatial analysis are used to investigate the hypothesis that either bauxitic soils or underlying geology increases the carcinogenic health risks to the population due to exposure from naturally occurring radioactive materials (NORM) in the soil environment over which they reside. The rationale for this study is the large distribution of bauxitic soils in Jamaica and a review of the last published 5-year cancer survey study of Jamaica. A negative health environment was defined as one where the excess lifetime cancer risk (ELCR) value exceeded the world mean value of 2.9 × 10−4 and the annual gonadal dose equivalent (AGDE) was a multiple of the acceptable level of 300 μSv/year. The excess lifetime cancer risk index in Jamaica ranges from 0.16 × 10−5 to 7.92 × 10−4 with a mean value of 1.63 × 10 −4. The mean value of the ELCR index in Jamaica was statistically significantly lower than the world mean value. The main areas of concern were the sections of the parishes of Manchester and St. Elizabeth which exhibited value of up to five (5) times the acceptable level of the ELCR index. The AGDE index showed a moderate correlation of 0.511 with a reclassified geology group (limestone and non-limestone) introduced in this study. The soils overlaying limestone formations in Jamaica were characterized by a statistically significantly higher dose rate exposure to the gonads of the population. Geological explanations for the levels of the primordial radionuclides are also discussed in this paper. The results suggested that limestone geology in Jamaica had a significantly higher mean value for both indices (ELCR and AGDE) when compared to other geologies. Since bauxitic soils predominantly overlay these rocks in Jamaica, the research hypothesis regarding the impact bauxitic soils is supported by the results of this study. The impact of geology was not significant, and probable causes are discussed.

Soil type and season mediated Phytophthora cinnamomi sporangium formation and zoospore release

The capacity of Phytophthora cinnamomi to sporulate and release zoospores in northern jarrah forest bauxite mining soils sampled in summer, winter and spring was determined. Soil types examined were a surface jarrah forest soil, a Bassendean sand and haul road, mine floor silt and a mine bauxite soil. Dependent variables indicating the stimulatory capacity of the soils were sporangia formed/mm2 of mycelium and numbers of viable zoospores released from sporangia formed. Forest soil was more stimulatory than the Bassendean sand, which was more stimulatory than the mining soils. Mine pit floor and haul road soil was least stimulatory. The numbers of zoospores released were significantly greater in the jarrah forest soil and Bassendean Sand than the mining soils. Season influenced the soil stimulatory capacity of jarrah forest, Bassendean sand and haul road soils, with sporangia counts for winter collected soils being significantly less than for summer and spring collected soils. The numbers of zoospores released were significantly greater for soils sampled in spring than those sampled in summer and winter. With respect to hygiene considerations, P. cinnamomi in host tissue does have the capacity to reproduce at low levels, relative to the forest surface soil, by sporangial formation and zoospore release in the mine pit floor and haulage road soils.

Minimal health impact from exposure to diet-sourced cadmium on a population in central Jamaica

Elevated concentrations of naturally occurring Cd have been found mainly in the bauxitic soils of central Jamaica at levels up to 100-1,000 times higher than typical worldwide averages. Some food crops cultivated on these soils absorb significant amounts of Cd. Autopsy studies of kidney Cd concentrations confirm elevated human exposure, and some long-term residents in central Jamaica exceed the general population average by a factor of two. Diet studies have ascertained that a population in central Jamaica is at risk of being exposed to Cd levels in excess of the Provisional Tolerable Weekly Intake (PTWI) set by the WHO of 7 μgCd/kg bodyweight/week, and the EU TWI of 2.5μgCd/kg bodyweight/week. Elevated levels of urine cadmium (U-Cd) and beta-2 microglobulin (β2-MG) concentrations were confirmed with a strong correlation between soil Cd and the U-Cd. Also, higher β2-MG concentrations (>200μg/g creatinine) were found in the population with U-Cd concentrations greater than 2.5μg/L. While this identification is often taken to indicate impairment in the reabsorption capacity of the renal tubules leading to renal disease, there is no evidence in the mortality records of enhanced deaths in central Jamaica compared with the general population resulting from renal disease or diabetes related complications. The highest median age of death in the island is found in Manchester, the parish with the highest average Cd concentration. While we have identified a possible Cd linked renal dysfunction, significant indications of morbidity are not present in the general population.

Mineralogical and geochemical investigations of the Dajia Salento-type bauxite deposits, western Guangxi, China

The Dajia Salento-type bauxite deposit in western Guangxi is hosted within the Quaternary ferrallitic soil profile, and it formed via breaking up, weathering and oxidizing of Permian bauxite orebodies occurring as a semi-continuous layer in the upper Permian. Mineralogical analyses reveal that diaspore, hematite and kaolinite are the major minerals in bauxite ores with small amounts of anatase, chamosite, gibbsite, goethite, illite, zircon, quartz and pyrite. The ore texture and mineral assemblage reveal that the depositional/diagenetic environment of the Dajia bauxite was much close to phreatic environment. Both the ore texture and the morphology of zircon grains also indicate that most of the bauxitic soils were transported a short distance. Diaspore is suggested to be non-metamorphic in origin and mainly formed in a reducing condition of diagenetic environment, while kaolinite is the product of the in situ epigenetic replacement of alumina in diaspore by dissolved silica. Geochemical analyses indicate that Al 2O 3, Fe 2O 3, SiO 2 and TiO 2 are the main components of the bauxite ores and trace elements such as Zr, Hf, Nb, Ta, Th and U were enriched during the bauxitization process. Simultaneously, Zr vs. Hf and Nb vs. Ta show a high correlation. Geochemical indices such as Zr/Hf, Nb/Ta and Eu/Eu* (among others) denote that the magmatic rocks related to the Emeishan plume in western Guangxi and the carbonates in the underlying Maokou Formation provided the main sources of material for the bauxite ores.

Variation in geochemical background levels for Jamaican soils

The complex soils of Jamaica may be subdivided into three groups on the basis of their Fe/Na concentration ratio, which reflects their genetic and pedological development, and the geochemical diversity of their parent materials. The three groups are non-Terra Rossa soils with Fe/Na concentration ratios of <40, Terra Rossa soils with Fe/Na 40–320, and bauxitic soils with Fe/Na >320. A series of ANOVAs demonstrate that the geometric means of As, Cu, Pb, Zn, Cd, Hg, Cr, U and Sm are significantly different from each other for all subpopulations, with the exception of Zn and Hg in Terra Rossa and bauxitic soils. A combination of the Tukey boxplot procedure and the visual inspection of cumulative probability plots is used to estimate the ranges of natural background for the above elements in the three soil environments. It is noted that these estimates based on total and near-total analyses overestimate the actual amounts of the elements that are bioaccesible.

Modeling interactions of Hg(II) and bauxitic soils

The adsorptive interactions of Hg(II) with gibbsite-rich soils (hereafter SOIL-g) were modeled by 1-pK surface complexation theory using charge distribution multi-site ion competition model (CD MUSIC) incorporating basic Stern layer model (BSM) to account for electrostatic effects. The model calibrations were performed for the experimental data of synthetic gibbsite–Hg(II) adsorption. When [NaNO 3] ⩽ 0.01 M, the Hg(II) adsorption density values, of gibbsite, Γ Hg(II), showed a negligible variation with ionic strength. However, Γ Hg(II) values show a marked variation with the [Cl −]. When [Cl −] ⩾ 0.01 M, the Γ Hg(II) values showed a significant reduction with the pH. The Hg(II) adsorption behavior in NaNO 3 was modeled assuming homogeneous solid surface. The introduction of high affinity sites, i.e., >Al sOH at a low concentration (typically about 0.045 sites nm −2) is required to model Hg(II) adsorption in NaCl. According to IR spectroscopic data, the bauxitic soil (SOIL-g) is characterized by gibbsite and bayerite. These mineral phases were not treated discretely in modeling of Hg(II) and soil interactions. The CD MUSIC/BSM model combination can be used to model Hg(II) adsorption on bauxitic soil. The role of organic matter seems to play a role on Hg(II) binding when pH > 8. The Hg(II) adsorption in the presence of excess Cl − ions required the selection of high affinity sites in modeling.

Comparison of bauxites from Jamaica, the Dominican Republic and Suriname

Neutron activation analysis, energy dispersive X-ray fluorescence and natural radioactivity measurements were used to determine 32 elements in three NIST bauxite SRMs from Jamaica, the Dominican Republic and Suriname, and the data related to the concentrations in 25 Jamaican bauxite soil samples. TheSRMs from Jamaica and the Dominican Republic fit theprofile of typical bauxitic soils from Central Jamaica, and the observed similar high values of Cd suggest that these bauxites may have similar origins. Except for Al, the bauxite from Suriname exhibits a very different elemental profile.

Multivariate relationships and spatial distribution of geochemical features of soils in Jamaica

Concentrations of 31 chemical elements in 165 soil samples from the tropical island of Jamaica were analyzed during the island-wide soil survey. Multivariate outliers were detected and remedied for quality control of the database. Multivariate analyses including principal component analysis (PCA), cluster analysis, and analysis of variance (ANOVA), and a geographic information system (GIS) were applied to study the geochemical features of element associations and sample clusters. The results show that rare earth elements, most of the heavy metals and trace elements (including As, Al, Cd, Ce, Co, Cr, Dy, Eu, Fe, Hf, Hg, La, Lu, Mn, Pb, Sb, Sc, Sm, Th, Ti, U, V, Yb, Zn) are enriched in the bauxitic soils relative to the non-bauxitic soils, and closely correlated with one another. Negative correlations between the bauxite-enriched elements and the mobile alkali and alkaline earth elements including Ca, Sr, Mg and Na are observed, showing the opposite tendencies of enrichment of the immobile elements and leaching of the mobile elements during the soil formation processes. The halogen elements of Br and I are also relatively enriched in the bauxitic soils, but they appear to be rather affected by sea-spray. Copper has poor correlations with all the other elements, which is likely to be related to mineralization. Significantly different concentrations of the bauxite-enriched elements are observed between the bauxitic and non-bauxitic soils.

The comparison of the results of two independent intercomparison studies (BAK-1 and SLB-1) from the same bulk material of a lateritic soil

A comparison of the results for major, minor and trace elements from the BAK-1 intercomparison study [1] and that of SLB-1 [2] are presented. These two independent studies were based on the same bulk material of a lateritic bauxite (soil) from Suriname but different preparation and homgeneity testing schemes were employed. The values for Al2O3, Fe2O3, TiO2 and LOI were not significantly different while the SiO2 value determined by the SLB-1 intercomparison run was 1.88%±0.34% in respect to 3.93%±2.65% from the BAK-1 study. An attempt to explain this difference in the SiO2 values was made on the basis of the sample preparation and the participating analytical laboratories. Finally, provisional values and uncercainty limits for major elements and LOI are presented for SLB-1 reference material.

Quartz arenites: review and interpretation

Quartz arenites (orthoquartzites) are exceptional sands (Pettijohn et al., 1972) that, in the past, have formed extensive and commonly thick formations. They are somewhat enigmatic in that they do not appear to be forming at the present time. This paper examines the origin of quartz-rich sands, documents the range of environments in which they are found and suggests a model for their genesis. Quartz sand is most commonly formed by tropical weathering of coarse-grained quartz-bearing rocks such as granite. It may be deposited as texturally immature fluvial sandstones, generally under a humid climate. With drying of the climate, quartz-rich bauxitic soils and sandy alluvium can be a substantial source of poorly rounded dune sands for major deserts. Quartz sand, when transported into shallow marine environments, becomes very well rounded through reworking by tidal currents. Such sand may spill into deep oceanic environments and by sedimentary or tectonic transport may come to rest in both stable and active tectonic settings. Quartz-rich sandstones can also be formed by diagenetic destruction of labile framework grains of immature sandstones. Precambrian orthoquartzites are commonly thick and widespread when compared to younger examples. The thinness of post-Silurian quartz arenites may be largely due to the trapping effect of land vegetation and solution of quartz by organic acids in weathering profiles. There is an abundance of shallow marine and fluvial quartz arenites in the Early Paleozoic and the Cretaceous; this is due to widespread continental flooding and a humid world climate following the disintegration of supercontinents. The shallow marine examples are commonly associated with bituminous, sometimes phosphatic shale, glauconite and possibly chamositic ironstone. There is an abundance of eolian quartz arenites in the Permo-Triassic. This is related to a widespread dry continental climate during assembly of the Pangean supercontinent.

Etude théorique de l'altération des plagioclases. Bilans et conditions de stabilité des minéraux secondaires en fonction de la la pression partielle de CO2 et de la température (0°C à 100 °C)

Using a theoretical approach based on experimental thermodynamic data and solution-mineral equilibria, the chemical ways of plagioclase weathering are calculated. Influences of temperature, CO₂ partial pressure and initial composition are discussed. Evolutions towards podzolic or bauxitic soils and towards kaolinitic or montmorillonitic products are confirmed.

Genesis, Mineralogy and Related Properties of West Indian Soils: I. Bauxitic Soils of Jamaica

AbstractThe red and brown bauxite soils of Jamaica occurring over hard, pure white limestone are strongly aggregated, freely drained soils of almost pure clay texture. They are of low fertility, nitrogen and potassium being very deficient. The red bauxite is deficient in available phosphate but not responsive to phosphorus fertilization. Phosphorus fractionation data show both soils to be adequately supplied with phosphorus. The brown bauxite is much higher than the red in total phosphate and in aluminum‐ and calcium‐bonded forms. Both soils are very high in iron‐bonded phosphate with the red bauxite having a greater percentage of the total phosphate in reductant soluble form. Chemical analysis shows the soils to be very high in Al2O3 content with little or no difference between the two soils. Silica content is very low. Iron is high and virtually all of it is present in dithionite extractable form. No minerals containing potassium seem to be present in the soils. Mineralogical study shows the Al2O3 to be present as gibbsite and boehmite in a ratio of 2:1 for both soils. The soils had less than 10% kaolinite, the brown bauxite being higher. Traces of chlorite were identified in both soils, and traces of montmorillonite were found in the deeper layers of the brown bauxite. Titanium was present as rutile and anatase in the brown bauxite but only as anatase in the red. The red bauxite is richer in goethite. The low content of silicates in the bauxites is associated with a low SiO2 content of the insoluble residue of the limestone and this is evidence for possible genesis of the bauxites from the underlying limestone.

The mode of formation, mineralogy and properties of some Jamaican soils

The properties of soils as roadmaking materials are influenced by their mineralogical composition, which in turn can be related to their geological origin and conditions of formation. These relations have been illustrated in a study of a number of soil types from Jamaica. The results show how studies of the formation and mineralogy of soils can contribute to an understanding of the engineering geology of the roadmaking materials of a region. Highly leached bauxitic soils occur on the well-drained limestone formation. The least-developed contained kaolinite and quartz, as well as iron and aluminium oxides, while in the most highly-developed only iron and aluminium oxide remained. The engineering properties of these soils are influenced by the cementing effect of hematite and may be compared with those of the Kenya red soils. The limestones were principally calcite, differences in strength being due to differences in the crystalline structure and cementing. A soil formed on a poorly-drained shale had a high montmorillonite content and was similar to the black montmorillonite soils of Kenya, being highly plastic and having poor compaction characteristics. Alluvial soils from low-lying areas contained kaolinite, montmorillonite, and vermiculite or illite, had high clay contents, and were very plastic.