Vander de Freitas Melo

CLAY-SIZED MINERALS IN PERMAFROST-AFFECTED SOILS (CRYOSOLS) FROM KING GEORGE ISLAND, ANTARCTICA

Cryosols from Maritime Antarctica have been less studied than soils from continental areas of Antarctica. In this work X-ray diffraction, difference X-ray diffraction, differential thermal analysis, thermogravimetry, transmission electron microscopy/energy dispersive spectroscopy and selective chemical dissolution were used to characterize the clay fraction of basaltic, acid sulfate and ornithogenic Cryosols from ice-free areas of Admiralty Bay, King George Island. Non-crystalline phases are important soil components and reach >75% of the clay fraction for some ornithogenic soils. Randomly interstratified smectite-hydroxy-Al-interlayered smectite is the main clay mineral of basaltic soils. Kaolinite, chlorite and regularly interstratified illite-smectite predominate in acid sulfate soils. Jarosite is also an important component of the clay fraction in these soils. Crystalline Al and Fe phosphates occur in the clay at sites directly affected by penguin activity and the chemical characteristics of these ornithogenic sites are controlled by highly reactive, non-crystalline Al, Si, Fe and P phases. Chemical weathering is an active process in Cryosols in Maritime Antarctica and is enhanced by the presence of sulfides for some parent materials, and faunal activity.

Toposseqüências de Latossolos originados de rochas basálticas no Paraná: I - mineralogia da fração argila

Com o objetivo de estudar o efeito de diferentes posicoes do relevo e materiais de origem sobre as caracteristicas mineralogicas da fracao argila dos solos, foram estudadas duas topossequencias de Latossolos (Latossolo Bruno acrico LBw e Latossolo Vermelho distroferrico LVdf) no Estado do Parana. A fracao argila foi estudada por difratometria de raios X, analise termodiferencial, analise termogravimetrica diferencial e analises quimicas. Os teores totais de Si, Al e Fe foram determinados apos a digestao das amostras com agua regia (mistura 3:1 de HCl 36 %: HNO3 68 %). Nos extratos resultantes da extracao com oxalato de amonio acido (OAA) e ditionito-citrato-bicarbonato (DCB), determinaram-se os teores de Fe e Al. O teor de Si no material de origem e a posicao dos perfis na paisagem foram importantes na definicao da mineralogia da fracao argila. O LBw e o LVdf foram classificados como caulinitico/goethitico e gibbsitico/hematitico, respectivamente. Verificaram-se maiores teores de SiO2 total e de caulinita (Ct) (373,3 a 574,3 g kg-1) para o LBw nos horizontes mais profundos (Bw2) e nos perfis mais baixos na topossequencia. A maior presenca de agua associada a drenagem limitada no perfil 4 do LBw (ponto mais baixo da topossequencia) favoreceu os maiores teores de oxidos de Fe e Al de baixa cristalinidade (OAA) e os menores teores de Fe2O3 DCB (oxidos de Fe mais cristalinos). De maneira geral, nao houve variacao consistente nos valores dos atributos cristalograficos da hematita e goethita de acordo com a profundidade do solo e posicao do perfil na topossequencia. Os menores indices de cristalinidade da Ct foram verificados nas amostras do LVdf, associados ao maior teor de Fe total no solo (r = 0,79**). O menor crescimento da gibbsita [menor valor do diâmetro medio do cristal no dominio (110)] foi observado no perfil 4 do LBw (posicao mais baixa da topossequencia).

Toposseqüências de Latossolos originados de rochas basálticas no Paraná: II - relação entre mineralogia da fração argila e propriedades físicas dos solos

A estrutura do solo (tipo, tamanho e grau de desenvolvimento) define a porosidade total do solo e a distribuicao relativa entre macro e microporos, sendo considerada uma das mais importantes propriedades do solo do ponto de vista agricola. O objetivo deste estudo foi avaliar a influencia da mineralogia da fracao argila, incluindo as caracteristicas cristalograficas dos minerais, sobre as propriedades fisicas de duas classes de Latossolos provenientes de rochas basalticas, em diferentes posicoes no relevo (topossequencia) no Estado do Parana. Para tal, procedeu-se a descricao morfologica dos perfis, e as amostras dos horizontes Bw1 e Bw2 foram submetidas a analises fisicas e micromorfologicas. A hematita (Hm), goethita (Gt) e Gibbsita (Gb) foram responsaveis pelo aumento na macroporosidade, porosidade total (PT) e pela reducao na densidade do solo (Ds) para o Latossolo Bruno acrico (LBw). Verificou-se influencia oposta para a caulinita (Ct). As correlacoes entre os atributos fisicos e os teores de Ct, Hm, Gt e Gb na fracao argila nao foram significativas para o Latossolo Vermelho distroferrico (LVdf). Aparentemente, os oxidos de Fe e Al de baixa cristalinidade foram mais importantes no incremento da macroporosidade e PT dos horizontes do LVdf. Com relacao as caracteristicas cristalograficas dos minerais da fracao argila, para o LVdf, apenas os coeficientes de correlacao entre o tamanho medio do cristal da Gb [DMC(110)] e a PT (correlacao negativa) e a Ds (correlacao positiva) foram significativos. Verificou-se comportamento semelhante para o diâmetro medio do cristal da Hm no dominio (104) para o LBw.

POTASSIUM AND MAGNESIUM IN CLAY MINERALS OF SOME BRAZILIAN SOILS AS INDICATED BY A SEQUENTIAL EXTRACTION PROCEDURE

The total contents of potassium (K) and magnesium (Mg) in selected Brazilian soils (Oxisols, Ultisols, Inceptsols, and Alfisols) developed from different parent materials were investigated to estimate the contribution of clay minerals to K and Mg reserves. Total K and Mg contents in the Na-saturated clay were determined by HF total digestion. The contribution of each mineral species to the total contents of K and Mg, was estimated by a sequential mineral extraction procedure, following the order: Na-saturated clay—1) amorphous aluminum and iron oxides (ammonium oxalate); 2) crystalline iron oxides (dithionite–citrate–bicarbonate); 3) amorphous aluminosilicate and gibbsite (0.5 M NaOH); 4) kaolinite (5 M NaOH); 5) mica (NaHSO4), and 6) feldspar (HF total digestion). In order to monitor mineralogical changes, after each extraction, the samples were studied by x-ray diffraction (XRD), analytical transmission electron microscopy (ATEM), differential thermal analysis and thermo-gravimetric analysis. Total amounts of K and Mg in the clay of the strongly weathered soils were very low, indicating a low reserve of these nutrients. Due to the high proportion of kaolinite in the clay fraction of these strongly weathered soils, this mineral accounts for more than 50% of the total K and Mg. The relative proportion of kaolinite and its contribution to the K and Mg reserves increased with weathering. In strongly weathered soils, the contribution of micaceous minerals to the total K and Mg ranged from 17 to 75% and from 8 to 59%, respectively, whereas in the younger soils the range was between 51 and 83%, and 35 and 82%, respectively. Only after the removal of the iron oxides and of the kaolinite was the mica concentration in the clay fraction high enough to be detected by XRD in some of the strongly weathered soils. Dioctahedral illite was the dominant micaceous mineral due to its high resistance to weathering. Microanalysis of individual mica particles by EDAX–ATEM revealed K2O and MgO concentrations between 62 and 121 g kg−1, and between 5 and 10 g kg−1, respectively.

Metais pesados em solos de área de mineração e metalurgia de chumbo: I - Fitoextração

A fitoextracao tem sido sugerida como alternativa viavel as praticas tradicionais de recuperacao de solos contaminados por metais pesados (remocao do solo e destinacao em aterros ou coprocessamento em cimento, etc.), em razao dos menores custos e por ser menos impactante ao ambiente. Este trabalho objetivou avaliar a fitoextracao induzida (uso de acido citrico como agente quelante) de metais pesados, com o cultivo de aveia-preta (Avena strigosa Schreber), girassol (Helianthus annuus L.) e grama-batatais (Paspalum notatum Flugge), em solos poluidos (solos 2, 3 e 4) de uma area de mineracao de Pb em Adrianopolis (PR). O solo 1 foi amostrado em area de mata nativa (referencia). O experimento foi realizado em casa de vegetacao, com tres repeticoes. Foram determinados os teores de Pb, Cd, Cu, Ni, Cr e Zn no solo com HNO3/HCl (3:1) concentrados. Apos a colheita das plantas, determinaram-se a massa de materia seca e os teores de metais pesados nas raizes e parte aerea (digestao nitrico-perclorica). Os solos contaminados (2, 3 e 4) apresentaram as seguintes faixas de teores de metais pesados (mg kg-1): Pb - 2.598,5 a 9.678,2; Cd - 1,9 a 22,2; Cu - 165,5 a 969,2; Ni - 22,6 a 38,4; Cr - 15,2 a 27,8; e Zn - 87,4 a 894,8. A adicao de quelante nao induziu a uma absorcao mais efetiva de metais pesados pelas plantas. O solo 2 possibilitou melhor crescimento das plantas, e o girassol deve ser preferido na fitorremediacao das areas sob as mesmas condicoes. Na area proxima a planta fabril (solo 3) e nas areas com grande ocorrencia de rejeitos (solo 4), a fitoextracao nao foi eficiente. Nesses ambientes, recomenda-se o estudo de outras plantas nativas e, ou, exoticas resistentes a altos teores de Pb (solo 3) ou a remobilizacao de solo mais rejeito para aterros industriais (solo 4).

Mineralogia das frações areia, silte e argila de sedimentos do grupo barreiras no município de Aracruz, estado do Espírito Santo

To investigate the mineralogical variations with depth, 11samples were collected down to 14m, in an exposed sediment packet of the Barreiras Group in Aracruz, Espirito Santo, Brazil.The sand, silt and clay fractions were studied by X-ray diffraction, differential thermal analysis, thermogravimetry and electron microscopy.The total contents of Fe in the clay and silt fractions and Ti and Zr in the silt fraction were determined by ICP after fluoridric acid extraction.Clay and silt fractions were submitted to selective and sequential mineral extractions, to characterize and quantify their constituents.The sand fraction showed a uniform mineralogical composition, almost solely quartz, with small amounts of mica, anatase, kaolinite and iron aggregates.In the 2.1; 4.2 and 7.7m depths, the occurrence of iron mottles with dark-red colour was observed.Silt fraction, as well, is constituted mainly by quartz, with stable kaolinite aggregates and hematite.The clay fraction showed a high proportion of kaolinite, reaching 950gkg-1 at 14m depth.The low contents of Fe in the sediments and the humid conditions of the Coastal Tablelands favored kaolinite concentration and removal of minerals, mainly Fe oxides. Contents of Goethite (main Fe oxide in the sediment) decreased with depth.The amount of low cristalinity material in the clay fraction is small, varying from 3.2 to 24.0gkg-1 for ammonium oxalate extraction and from 0.6 to 3.5gkg-1 for extraction with 0.5molL-1 NaOH, due to the high degree of development of the sediments.For the same reason, the mica contents in the clay and silt fractions were lower than 5.0gkg-1.As observed for kaolinite, the mica content in the clay fraction increased with depth.

Indicadores de qualidade de solos de área de mineração e metalurgia de chumbo: II - Mesofauna e plantas

SUMMARY : SOIL QUALITY INDICATORS IN LEAD MINING ANDMETALURGY AREA. II – MESOFAUNA AND PLANTS The influence of soil management or the contaminant application to the soil, usuallyinduce to a quicker response in the soil mesofauna than in other pedogenic properties; theseorganisms are therefore good environmental quality indicators. The aim of this study was toidentify and quantify the organisms groups of the soil mesofauna and determine Pb and Zncontents in plants in the mining and metallurgy plant in Adrianopolis (PR),to originatebiological indicators of the quality of these solis. At the selected locations the followingcontamination forms were analized: site 1 – reference (native wood); site 2 – residue incorporatedin the profile; sites 3 and 6 – close to the chimneys of the plant, with potential import ofparticulate matter; site 5 – great waste volume covering the soil. Berlese funnels were utilizedto collect samples from the 0 to 5 cm layer (20 funnels x 5 sites x 1 layer x 4 times = 400samples). After the separation of the mesofauna, the organisms were selected and identified.Ants samples were microwave digested with concentrated HNO

Metais pesados em solos de área de mineração e metalurgia de chumbo: II - formas e disponibilidade para plantas

The forms and availability of heavy metals in contaminated soils determine the uptake potential of plants and water contamination by leaching. In this study different methods of chemical extraction were used, in order to identify the forms of Pb, Cd, Cr, Ni, Cu, and Zn and evaluate the availability of these pollutants for sunflower (Helianthus annuus L.), black oat (Avena strigosa Schreber) (exotic species) and Bahiagrass (Paspalum notatum Flugge) (native species), as indicators, in soils of Pb mining and metallurgy in Adrianopolis, state of Parana, Brazil. Soil samples were collected in the 0-40 cm layer in four environments of the area: soil 1 - control (native forest); soil 2 - waste in soil profile; soil 3 - near the factory chimney (deposition of particulate material); soil 4 - heavy deposition of waste. The following extraction methods were used: DTPA-TEA pH 7.3; Ca(NO3)2 0.5 mol L-1; HNO3 0.5, 1.0 and 4.0 mol L-1, and concentrated HNO3/HCl (3:1). The plants were grown in a greenhouse, with three replications. The increase of pseudo-total, exchangeable and non-exchangeable heavy metal contents was verified; the highest contents of Pb and Zn were extracted by HNO3/HCl; 9,678.2 and 894.8 mg kg-1, respectively. Soil heavy metals based on acid extractors HNO3 0.5, 1.0 and 4.0 mol L-1 and HNO3/HCl were strongly correlated with each other. The extractor based on chelation (DTPA-TEA pH 7.3) was not efficient to predict the availability of heavy metals for plants under the study conditions. The nitric extractions should be preferred to determine Pb and Zn plant availability in the area.

Propriedades químicas e cristalográficas da caulinita e dos óxidos de ferro em sedimentos do grupo barreiras no município de Aracruz, estado do Espírito Santo

Detailed chemical and crystal properties of the kaolinite (Ka) and iron oxides in the Barreiras Group soils and sediments (Coastal Tablelands) are little known. Eleven samples were collected (0,7; 1,4; 2,1; 2,8; 3,5; 4,2; 4,9; 5,6; 7,7; 10,5 and 14m) in an exposed sediment sequence in Aracruz, Espirio Santo State, Brazil, in order to study the characteristics of these minerals with depth. Clay and silt fractions were studied by X-ray diffraction (XRD), differential thermal analysis and electron microscopy. Total contents of Fe, Cr, Mn, Ni, Pb, Ti and Zr of the clay fraction were determined by ICP after fluoridric acid extraction. The contents of Al, Si and microelements were determined in ammonium oxalate (AO) and dithionite-citrate-bicarbonate (DCB) extracts. The chemical composition of kaolinite in the clay fraction was determined by extraction with NaOH 5molL-1 and in the silt fraction by the combined heating and extracting with NaOH 0,5molL-1. The average Fe2O3 content in the kaolinite of the clay fraction (20.7gkg-1) was higher than those obtained for the silt fraction (5.2gkg-1). The interplanar space, mainly in the b axis, was increased, due to Fe substitution in the kaolinite structure. The properties of kaolinite (such as size and shape) did not substantially differ with depth, although less crystalline kaolinite was found at the surface, suggesting an interference of organic matter. With reference to the iron oxides, the Fe2O3 contents extracted by DCB in the clay fraction decreased with depth. The isomorphic substitution of Fe for Al was greater in goethite (Gt) in relation to hematite, with a trend of higher values at the sediment surface. The iron oxides presented little association with microelements, mainly, Ni, Pb and Ti.

Potássio e magnésio em minerais das frações areia e silte de diferentes solos

Os solos mais intemperizados, desenvolvidos nos tropicos umidos, apresentam baixa reserva de nutrientes nas fracoes mais grosseiras. Para avaliar a presenca de potassio e magnesio nos minerais, amostras das fracoes areia e silte de solos desenvolvidos de diferentes materiais de origem e estadios de intemperismo dos estados de MG, ES, RS e RR foram estudadas por difratometria de raios-X (DRX), analise termodiferencial, analise termogravimetrica diferencial e microscopia eletronica. Os teores totais de elementos da TFSA e das fracoes do solo foram determinados por digestao fluoridrica das amostras. A fracao silte tambem foi submetida a extracoes sequenciais e seletivas dos minerais para estimar a contribuicao das especies minerais nos teores totais de K e Mg. A fracao areia dos solos mais intemperizados e muito pobre em nutrientes, com predominio de quartzo, indicando limitada reserva de K e Mg. Para os solos mais jovens, esta fracao apresenta os maiores teores totais de K e Mg, superando as fracoes mais finas do solo, com presenca de minerais primarios, como mica, feldspato e anfibolio. Particulas de mica e agregados de caulinita foram as principais fontes de K e Mg totais para as fracoes areia e silte dos solos mais intemperizados. Os minerais micaceos nestes solos, identificados e analisados por microscopia eletronica, apresentaram teores de K2O variando de 33,3 a 62,8 e 27,4 a 98,1 g kg-1 e de MgO de 76,5 a 116,8 e 19,7 a 68 g kg-1 para as fracoes areia e silte, respectivamente. Devido aos baixos teores de mica na fracao silte dos solos mais intemperizados (menor que 1%) e a alta proporcao de quartzo, mesmo apos a extracao de caulinita, a concentracao da amostra nao foi suficiente para deteccao de minerais micaceos por DRX. Apenas para o LV de Barroso (MG), verificou-se o aparecimento de discreta reflexao de mica.