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Concentrations of one metalloid (As) and eight metals (Cd, Cr, Cu, Hg, Mn, Ni, Pb, and Zn) were determined in tissues (muscle, liver, and kidney) of eight snake species (Bothrops neuwiedi, Crotalus durissus, Dipsas mikanii, Epicrates crassus, Helicops modestus, Micrurus carvalhoi, Oxyrhopus guibei, and Oxyrhopus trigeminus) from Lagoa Santa Karst. Except for Cu and Zn, all other analyzed elements were detected in concentrations within the ranges previously reported for snakes inhabiting polluted areas, emphasizing Hg (specific Hg mean concentrations varied from 0.87 to 9.76 µg g-1 d.w). The highest mean concentrations of all elements except Zn were found in muscle samples of the false corals O. guibei (means ranged from 2.01 [Pb] to 9.76 [Hg]). The highest Zn mean concentration (13.77 µg g-1 d.w) was detected in the kidney of the water snake H. modestus. No significant correlation was found between element concentrations and body size for all species. Significant interorgan differences were observed for As, Cr, Cu, Hg, Mn, Pb, and Zn concentrations in the three tissues in H. modestus. Significant interspecific differences were found in at least one organ for all elements. Significant pairwise differences were found between diet specialist species and between these species and broader diet species, while no significant difference was found between the broader diet species. The bioaccumulation of As and metals in snakes from Lagoa Santa Karst could be associated with natural rock dissolution and erosion processes but also with the wide-scale mining in the region and the increased agriculture and urbanization.

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Drinking water with a high natural concentration of fluoride (F-) has serious consequences for the health of the rural population in the state of Guanajuato, Mexico, where the water contains levels of F- that are not allowed by national and international regulations (1.5 mg/L). This health problem is very common in multiple states throughout Mexico where drinking water is generally extracted from aquifers that are hosted in fractured volcanic rocks of the Tertiary. These aquifers show similar geological characteristics: deep basins that formed as a result of felsic eruptive events and the extensional deformation of the Basin and Range and are now filled with unconsolidated sediments. In this study, we assessed the occurrence of F in volcanic rocks collected at 11 sampling sites along the Sierra de Codornices in Guanajuato (ranging between 0.01299 and 0.146 wt%, average 0.039 wt%, and SD = 0.039 wt%; n = 10), a region where both rural and urban communities consume drinking water with a high F- content (up to 7.1 (mg/L). The F content is dispersed in volcanic rocks, and the highest levels are present in felsic rocks. The statistical and hydrogeochemical results of a sampling campaign of 32 wells in the Juventino Rosas (JR) and Villagran (Vill) municipalities in 2019 suggest that F- mobilization in groundwater is the product of silicate weathering and the dissolution of volcanic glass, alkaline desorption in the surfaces of F-containing minerals, and possibly ion exchange of minerals and clays or deep fluids enriched with F-, in addition to the precipitation of carbonates that decrease the Ca2+ concentration in groundwater. All of these processes can be accelerated by groundwater geothermal characteristics within the study area. The hydrogeochemical, fluoride exposure risk, and fluoride pollution index (FPI) results, as well as the epidemiological survey, indicate that teenagers and older adults from Praderas de la Venta are at risk of exposure to F- due to the high concentrations ingested over a long period, the toxicity of the element, and its ability to accumulate in the bones. Extended exposure to elevated levels increases the risk. This work allows us to observe how the populations of JR and Vill can be exposed to high F- contents in drinking water due to the geological characteristics of the region.

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Pristine soils under native vegetation can present high levels of potentially toxic elements when developed from the weathering of some unusual parent materials, especially ultramafic rocks and some metal ores. Here, we used various selective extractions in order to study the partition and potential availability of As in eight soils developed from steatite (a talc-rich rock) on an ultramafic hill in Brazil. Soils varied from shallow Entisols on the summit to Inceptisols and Oxisols on slopes and footslopes, where total As contents (determined by X-ray fluorescence) reached levels as high as 225 mg kg-1, which might raise concerns about their potential agricultural use and occupation. Despite these high values for pristine soils, water- and Mehlich-available As were nil or negligible in all soils, whereas oxalate-extractable As reached a maximum 4.2 mg kg-1, and the highest semi-total (nitric acid digestion) was 9.3 mg kg-1. However, As relative availability (compared to total As) varied widely among soils, with one Inceptisol (with a total 11-19 mg kg-1) reaching 100% of its total As extractable by nitric acid, whereas an Oxisol showed <0.1% in nitric acid extract. Generally, we can conclude that, in soils with the highest total As concentrations, most As is contained within resistant, coarse phases such as primary magnetite, chromite and others, and a minor but still considerable part is bound to secondary Fe oxides. Thus, despite the unusually high As contents for soils under pristine savannic and forest native vegetations, the different As pools assessed here apparently do not raise immediate concerns where ultramafic rocks rich in Fe oxides give rise to soils under tropical climate. However, it is theoretically possible that subsoil saturation and Fe oxide reduction release some As in ground- and surface waters, which deserves further investigation.

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This data article describes the connected pore cluster data from segmented nano-images of rocks related to a geothermal system. The collected samples include two (2) vesicle-amygdaloidal basalt (host rock) and four (4) horizons collected from a siliceous sinter mound (rock precipitated from hot waters). All the samples have undergone computed tomography scanning using a SkyScan 2211 multiscale X-ray nano-CT system (Bruker®), and the slices were analyzed using the Digital Rock Physics (DRP) approach. Pore volume and fluid permeability in the three directions were calculated with scripts of Python (v.3.9) and the visualizations of the 3D models were run with Paraview (v.5.10) software. The petrophysical properties, diagrams, and figures were produced by stacking the 2D projections (8-bit grayscale *.png images format) from the scanning. Raw data (images) were deposited in a repository, which has granted a persistent identifier (Mendeley Data: https://data.mendeley.com/datasets/srpxhpd37p/2). This article provides a study case to handle the data that test the interconnectivity and ability to transport fluids and/or exogenous matter carried during high-flow events in rocks outcropping at the surface level of a geothermal system.

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An analytical method for sample preparation of igneous rocks and subsequent determination of Si, Na, K, Ca, Mg, Al, Fe, Mn, Ba, Sr, and Ti by means of microwave induced emission spectrometry (MP-AES) was developed and validated. The proposed sample preparation procedure avoids the use of perchloric acid and provided accurate results even for silicon determination using an acid digestion with hydrofluoric acid. The determination of major elements in rocks is required for the design of classification diagrams that provides relevant information for geochemical analysis.•MP-AES showed to be an adequate technique to measure major and some trace elements that are relevant for classification of igneous rocks.•This method is in better agreement with the principles of the Green Analytical Chemistry and constitutes a reliable alternative to classical analytical and tedious procedures used for geochemical analysis.•The methodology was successfully applied to chemical classification of rocks from Valle Chico (Uruguay) using a Total Alkali-Silica Diagram (TAS).

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Considering the higher radiosensitivity of children in comparison to adults, studies related to children's exposure to ionising radiation have been long considered of relevance. For this study, the MCNPX2.7.0 Monte Carlo code and four paediatric voxel computational anthropomorphic phantoms, of both genders and aged 5 and 10 years, were used to simulate scenarios, where children are exposed to natural radiation emitted by sources in the ground by radionuclides of40K and of232Th and238U radioactive series. These elements are part of the composition of ten different types of ornamental rocks obtained from three regions of Brazil, and used as architectural material for flooring of houses. The virtual paediatric anthropomorphic phantoms were positioned in a room with dimensions of (4.0 × 5.0 × 2.8) m3filled with atmospheric air and a 3 cm thick granitic floor acting as a uniformly distributed planar gamma radiation source. The walls of the room were composed of 20 cm thick concrete. Gonads, bone marrow, bladder, colon, and skin were found to be the organs which receive the highest doses. The mean values of effective dose per air kerma at 1 m above the ground summed for all three radionuclides, were 0.96 and 0.68 Sv Gy-1for the 5 and 10 year old phantoms, respectively. The obtained results showed that the granitic rocks considered implicate annual effective doses which are 69%-78% lower than the annual limits, recommended by ICRP Publication 103.

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In August 2019, thousands of tons of crude oil from an unidentified source began washing up on the Brazilian coast, causing the most severe environmental disaster that has ever impacted the South Atlantic Ocean. Paiva beach, which has some of the best-preserved tropical coral reefs on the Brazilian coast, was one of the coastal environments most severely affected by this oil. We report on the impact of the disaster on the local population of the symbiotic polychaete Branchiosyllis spp. associated with the sponge Cinachyrella sp. Following the oil spill sponges were found with oil stains on their surface and in their channels, and oil droplets were identified among the grains of the sediment accumulated within these channels. During this same period, the polychaetes in sponges had oil droplets on the surface of the body or in their pharynxes. Solubility tests using mineral oil and Raman spectra indicated that these oil droplets, found in both the sponges and the polychaetes, had similar chemical characteristics to those of the crude oil that washed up on the beach. Following the disaster, the abundance of Branchiosyllis declined sharply, although there was no significant shift in the mean size of individuals. By December 2019, the density of polychaetes was significantly lower than in the preceding months (107.9 ± 28.31 ind.10 mL-1 of sponge in August 2019 vs. 18.62 ± 35.48 ind.10 mL-1 of sponge in December 2019). This abrupt reduction in abundance with no change in the mean size of the individuals indicates that mortality affected all size (age) classes similarly, which is typical of anthropogenic impacts rather than natural mortality. It is thus clear that the contamination of polychaetes with crude oil increased mortality, causing a significant reduction in the Branchiosyllis populations of the coral reefs of Paiva beach following the 2019 oil spill.

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The porosity of volcanic rocks can be strongly affected by secondary processes such as the percolation of water and hydrothermal fluids, thus promoting crystallization of secondary minerals in the pores. With an aim to evaluate the impact of secondary mineral fillings, this paper shows the segmentation of secondary and filled pores based on the micro-CT technique. The mineralogy of the sample was analyzed with optical microscopy. Multiscale analysis was performed to determine the total porosity before and after the processes. The results show the influence on the permeability parameter caused by crystallization.

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BACKGROUND: This study evaluated the effect of treatment with TKI-258 on apoptosis, involving Rho GTPases and their effectors in SCC-4 cells of oral squamous cell carcinoma. METHODS: Markers of cell death and apoptosis were analyzed in control and TKI-258-treated SCC-4 cells by flow cytometry. The involvement of Rho GTPases and effectors in the induction of apoptosis by TKI-258 was evaluated by quantification of cleaved PARP. Also, gene expression analysis of those proteins was performed. RESULTS: The treatment with TKI-258 led to a significant increase in cell death (7-AAD) and apoptosis (annexin V and cleaved PARP). When Rho GTPases were stimulated with LPA and inhibited with toxin A Clostridium difficile, the percentage of apoptotic cells increased and decreased, respectively. A similar effect was found when the treatment was with TKI-258 combined with LPA and toxin A. Treatment with TKI-258 significantly increased RhoA gene expression, while RhoB, RhoC, Rac1, and Cdc42 decreased significantly. ROCKs inhibitors (Y-27632 and HA-1077) reduced apoptosis compared with control. TKI-258 combined with Y-27632 or HA-1077 led to an increase in apoptosis compared with inhibitors only. Treatment with TKI-258 led to an increase in ROCK1 and ROCK2 gene expression, and a decrease in PAK1 and PAK2 gene expression. CONCLUSIONS: TKI-258 stimulates apoptosis in SCC-4 cells of oral squamous cell carcinoma. Possibly, RhoA GTPase and their effectors ROCKs participate in the signaling pathway inhibited by TKI-258. CLINICAL RELEVANCE: Therapies with multi-target inhibitors, such as TKI-258, may be promising alternatives for the clinical treatment of oral squamous cell carcinoma.

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Rock powders are low-cost potential sources of most of the nutrients required by higher plants for growth and development. However, slow dissolution rates of minerals represent an obstacle to the widespread use of rock powders in agriculture. Rhizosphere processes and biological weathering may further enhance mineral dissolution since the interaction between minerals, plants, and bacteria results in the release of macro- and micronutrients into the soil solution. Plants are important agents in this process acting directly in the mineral dissolution or sustaining a wide diversity of weathering microorganisms in the root environment. Meanwhile, root microorganisms promote mineral dissolution by producing complexing ligands (siderophores and organic acids), affecting the pH (via organic or inorganic acid production), or performing redox reactions. Besides that, a wide variety of rhizosphere bacteria and fungi could also promote plant development directly, synergistically contributing to the weathering activity performed by plants. The inoculation of weathering bacteria in soil or plants, especially combined with the use of crushed rocks, can increase soil fertility and improve crop production. This approach is more sustainable than conventional fertilization practices, which may contribute to reducing climate change linked to agricultural activity. Besides, it could decrease the dependency of developing countries on imported fertilizers, thus improving local development.

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RESUMO Este trabalho objetivou imobilizar metais pesados presentes nos resíduos de quartzito por meio da incorporação em argamassas em substituição total ao agregado natural. Dois tipos de resíduos foram utilizados: os resíduos de fragmentação das aparas (QS) e os do pó de serragem (QP). Os resíduos foram caracterizados por fluorescência de raios X, difração de raios X e ensaios de toxidade conforme metodologia da Norma Brasileira (NBR) 10005, da NBR 10006 e do Toxicity Characteristic Leaching Procedure (TCLP) 1311. Então, foram analisadas composições de argamassas contendo cimento, cal e os resíduos (QS, QP) utilizando-se a técnica de delineamento de mistura, determinando os melhores traços, o melhor tipo de cura (imersa ou úmida) e, posteriormente, avaliando a resistência dos corpos de prova após cura. A caracterização do resíduo de quartzito revelou a presença de vários metais pesados e extratos lixiviados em contato com a água, classificando-o como resíduo de Classe I — Perigoso. Os resultados indicam que as composições determinadas foram capazes de imobilizar os metais pesados presentes nos resíduos de quartzitos, bem como resultou em argamassas com resistências mecânicas superiores a 2 MPa. Por fim, mostrou-se que essa técnica de solubilização e estabilização dos contaminantes presentes nos resíduos de quartzito é uma alternativa tecnologicamente viável e ambientalmente adequada para a destinação final desses resíduos.

ABSTRACT This work aims to immobilize heavy metals present in the quartzite residues by means of the incorporation in mortars in total substitution to the natural aggregate. Two types of residues were used: quartzite sand (QS) and powder (QP). The residues were characterized by x-ray fluorescence, x-ray diffraction, and toxicity tests according to the methodology of the NBR 10005, 10006 and Toxicity Characteristic Leaching Procedure (TCLP) 1311. Then, compositions of mortar containing cement, lime and residues (QS, QP) were analyzed using technique of designing the mixture, determining the best mixture, the best type of cure (immersed or wet), and subsequently evaluated at resistance of the body of evidences after curing. The characterization of quartzite residue revealed the presence of multiple heavy metals and leached extracts in contact with the water, classifying it a Class I-Hazardous waste. Regarding the production of mortars, the results indicated that the compositions determined were able to immobilize the heavy metals present in the quartzite residues, as well as resulted in mortars with mechanical resistances higher than 2 MPa. Finally, it was shown that this technique of solubilization and stabilization of contaminants present in quartzite residues is a technologically viable and environmentally adequate alternative for the final destination of these residues.

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Soil trace evidence can be useful in criminal investigations. A homicide which had occurred in South Brazil been concluded through the courts with a guilty conviction. A spade with soil traces adhering to it was seized from the confessed killer's house, it having been established that it had been used to bury parts of the victim's body. In the context of this confession, it provided an opportunity to test a protocol of analysis and verify the potential of discriminate soil sample analysis in such case works. This allowed us to test the practice of sequential analysis which had been developed for forensic case works in Brazil, with three sequential extractions: (i) 0.2 mol/L pH 3.0 ammonium oxalate; (ii) dithionite-citrate-bicarbonate; and (iii) 0.5 mol/L NaOH. It was possible to predict the sequence of events related to the homicide by using the sequential extraction technique and to conclude that: (i) the A horizon soil from the burial location of the torso was found to be very similar to the soil samples which had been recovered from the spade, which was able to be established despite there only being a small amount of soil adhering to the spade; (ii) the location where the legs were buried contributed a low amount of soil adhering to the spade. Therefore, it is suggested that, where possible, sequential extractions should be prioritized from a questioned sample to best provide information about the likely sequence of contact places and this test likely scenarios and criminal events.

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The increase in demand for highly soluble fertilizers brings a global sustainability concern. Alternative sources for traditional fertilization are therefore needed. Rock powder use has been proposed as an alternative approach to soil remineralization. However, research on the agricultural potential of minerals and rocks as alternative sources of nutrients is limited to changes in soil chemical attributes or effects on crop yield. In this work, we report an experimental study addressing the dissolution of two silicate rock-derived powders (andesite and dacite) that were produced during mining activities in Southern Brazil. The rock powders were exposed to Milli-Q water at pH (7.4-8.8) range, in solutions of 0.1 mol L-1 citric acid at pH range 2.1-3.3, and Milli-Q water acidified with 0.5 mol l-1 acetic acid (pH 5-5.8), in a continuous mechanical rotatory shaker at room temperature. Dissolution kinetics were determined as a function of reaction times at 24 to 5760 h, and solution pH. Based on this kinetics, dissolution rates were determined for the individual powders and compared to expected values for aluminosilicates. Based on this comparison, it was shown that the application of andesite and dacite rock-derived powder to replace high soluble fertilizers is feasible due to high dissolution rates of their minerals. The average andesite dissolution rates in Milli-Q water, in citric acid solution, and in Milli-Q water acidified with acetic acid were 2.1 × 10-5, 1.92 × 10-1 and 6.3 × 10-4 mmol cm-2 s-1, respectively for Ca, being 183%, 22.6%, and 69.2% higher than for the dacite rock. This make andesite rock a potential substitute for carbonate-based liming. In contrast, the average dacite dissolution rates in Milli-Q water, in citric acid solution, and in Milli-Q water acidified with acetic acid were 1.05 × 10-5, 7.22 × 10-5, and 3.72 × 10-5 mmol cm-2 s-1, respectively for K, being 72.0%, 61.4%, and 73.6% higher than the andesite rock. This highlights its potential use as a K source for agriculture to replace highly soluble K-fertilizers.

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Twenty caves located in a high altitudinal quartzite area in Brazil were examined for invertebrate richness and composition and in terms of environmental factors that determine community structure. We evaluate how distance, altitude, cave extension, environmental stability, number and size of cave entrances and stream presence can act on species composition and richness. The caves presented a high richness of troglophilic (463 spp.) and troglobitic species (6 spp.) in relation to other siliciclastic caves around the world. The average richness was 39.55 species per cave (sd = 21.87), the quantitative similarity among caves was 41% and turnover was βrepl. = 0.769. Araneae (20% of the sampled species), Diptera (18%) and Coleoptera (14%) were the dominant orders regarding species richness. Only twenty percent of the caves were placed out of the confidence interval of the average taxonomic distinctness (∆+); however, the ∆+ decreased with the increase of environmental stability. Cave extension and stream presence were the main factors determining the variation of species composition among caves. Cave extension also influenced species richness variations. Furthermore, the total richness and richness of troglobitic species increased with cave extension. The threats to these habitats further revealed that the fauna is at risk due to tourism, trampling and natural soil erosion that can promote microhabitat alterations. Therefore, quartzite caves also require special attention regarding conservation actions in order to keep their natural biological dynamics.

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Kinematic indicators, including certain strain fringes, represent an important group of structures related to the progressive deformation in rocks. The evolution of these fibrous textures can be explained by the combination of multiple mechanisms of deformation and fluid flow, mainly controlled by the orientation of the strain field and the morphology of the grains. In general, the observations are done with an optical microscope and compared with computational models of growth. This work proposes a combination of crystallographic and cathodoluminescence data obtained in rocks from banded iron formations of the Iron Quadrangle in Brazil to represent an example of how complementary analytical techniques can be useful to understand geological problems. The chosen sample exhibits a strain fringe structure of quartz around a clast of magnetite partially transformed into goethite and hematite. Through the crystallographic data it was possible to identify the grain boundary morphology and domains of low deformation areas. On the other hand, the cathodoluminescence signal evidenced the occurrence of grains with a higher concentration of crystalline defects.

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We studied the molecular taxonomy and diversity of cultivable rock fungi from Antarctic islands. From 50 rock samples, 386 fungal isolates were obtained and identified as 33 taxa of 20 genera. The genera Cladophialophora, Cladosporium, Cyphellophora, Eichleriella, Paracladophialophora, and Penicillium displayed the highest densities. Ecological diversity indices showed that the fungal assemblages are diverse and rich with low dominance. The genera Cladophialophora, Cladosporium, and Penicillium showed a broad distribution from rocks of the various islands. One hundred and fifty-nine fungi, grown at 37 °C, were identified as Penicillium chrysogenum, Fusarium sp., and Rhodotorula mucilaginosa. One hundred and three fungi displayed haemolytic activity, 81 produced proteinase, 9 produced phospholipase, and 25 presented dimorphism and a spore diameter ≤ 4 µm. The Antarctic Peninsula region appears to be under the effects of global climate changes, which may expose and accelerate the rock's weathering processes, and expose and release cryptic fungi and other microbes, especially those with innate pathogenic potential, previously arrested in rocks. Consequently, these rocks and their particles may represent a vehicle for the dispersal of microbial propagules, including those able to spread pathogens, along, across, and out of Antarctica.

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Six new species of Geomonhystera (Nematoda, Monhysterida: Monhysteridae) Andrássy, 1981, are described and illustrated, five from México and one from Ecuador. The new species have many features in common and in common with at least several other species of the genus. Consequently, those features individually are not very useful for species-level diagnosis. They include the cuticular striation which, under light microscopy, ranges from fine to apparently smooth; however, scanning electron micrographs reveal very fine cuticular striation on all the new species. All the new species have a few body setae scattered along the length of the body and the vulval lips of females are slightly protruding. As for other species of the genus, there is considerable overlap in the ranges of standard morphometric characters so a combination of standard and additional morphometrics, as well as qualitative characters, is necessary for species separation. Geomonhystera mexiquense sp. n., collected from moss on a rock and on the trunk of Quercus crassipes in Juchitepec, México State, México, has outer labial setae that are unsegmented and 44-67% of the head width, the cephalic setae are thin, unsegmented and 31-50% of the head width; the vulval lips protrude slightly. Geomonhystera michoacana sp. n., collected from moss on a rock in Tzararacua National Park, Uruapan, Michoacan State, México, has a very finely-striated cuticle which appears almost smooth and bears rare cervical and caudal setae; the tail is long, 15-17% of the body length, and the rectum also is long, 23-32 (27±2.0) µm. Geomonhystera longispiculata sp. n., collected from an epiphytic plant in the botanical garden of the Ecology Institute in Jalapa, Veracruz State, México, is distinguished from all the species of the genus by the long, slender spicules, 55-85 (75±3.0) µm. The cuticle has conspicuous fine striation and there are somatic setae scattered along the body. Geomonhystera ecuatoriana sp. n., collected from moss on the trunk of Scalesia pedunculata growing on the twin volcanoes of Isla Santa Cruz, Galapagos, Ecuador, has fine cuticular striation and a few small body setae; the unsegmented outer labial setae are 42-54% of the head width and the cephalic setae are thin, unsegmented and 33-45% of the head width; the vulval lips protrude slightly and the vulva-anus distance is 37-48 µm or 2.1-2.5 times anal body diameter. Males of G. ecuatoriana have slightly arcuate spicules, 35 µm long. Geomonhystera galindoi sp. n., collected from moss on the trunk of Quercus peduncularis in San Pablo Ixzayo, Texcoco, México State, México, has fine cuticlar striation and a few fine body setae, the vulval lips are slightly protruding; the vulva-anus distance is 35-50 (41±0.9) µm, 1.5-2.2 (1.9±0.2) times anal body diameter. Males of G. galindoi are slightly ventrally curved with the posterior end strongly curved, giving the body a hook-shaped appearance. Geomonhystera chiautzingoensis sp. n., collected from moss on the trunk of Crataegus mexicana in Chiautzingo, Puebla State, México, has exceedingly fine striation of the cuticle and outer labial and cephalic setae that are less than 50% of the head width. Additionally, G. dubia Siddiqi Shahina, 2004 was sollected in soil samples around a plum tree (Prunus sp.) in the garden of Montecillo Campus, Colegio de Postgraduados, Texcoco, México State, México This species has a small body with fine cuticular striation and a few sparsely-distributed body setae; the outer labial and cephalic setae are unsegmented, 5-8 and 3-5 µm long, 56-80% and 33-50% of the head width, respectively; the vulval lips protrude slightly but are sometimes flush with the body contour.

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Fe-rich Oxisols on mafic rocks in Brazil generally have high magnetic susceptibility with high contents of some trace elements. These are taxonomically similar soils; however, differences in magnetic and geochemical properties may affect agricultural or environmental usability and subsequent management. This study investigated the pedogenesis of Fe-rich Oxisols from various parent materials and evaluated the lithogenetic influence on magnetic susceptibility and trace elements contents. Soil samples were collected from Bw horizons in 13 Rhodic Oxisols and a Typic Oxisol developed from several parent materials in Minas Gerais State, Brazil. Soils were analyzed by X-ray diffractometry (XRD) and magnetometry. Soil chemical analyses consisted of sulfuric and total (tri-acid) digestions and selective Fe oxides dissolutions and statistical correlations were determined. Fe-rich Oxisols presented a typical mineralogical composition of highly weathered soils with structural stability. The results confirm the difficulty to identify accurately magnetic minerals in different grain sizes using XRD. However, coarse fractions still exert dominant influence on the magnetic properties of the Fe-rich Rhodic Oxisols. In addition, coarse fractions probably contribute to the enrichment of superparamagnetic particles for the clay fraction. Although highly weathered, Fe-rich Oxisols may have their geochemical attributes still controlled by the parent material, where trace elements seem to be correlated with the magnetic minerals in the coarse fractions. Thus, the natural replacement of some trace elements from soil-solution equilibrium reactions during plant development could be more effective in soils with higher magnetic particles concentrations in the coarse fractions.(AU)

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