Nelson Mazur

Concentrações naturais de metais pesados em algumas classes de solos brasileiros

ABSTRACT NATURAL CONTENTS OF HEAVY METALS IN SOME BRAZILIAN SOIL CLASSESThe heavy metals background levels for evaluation of a possible contamination are still notdefined in Brazilian soils. The objective of this study was to measure the content of the heavymetals Cd, Cr, Cu, Fe, Mn, Ni, Zn, in several brazilian soils, under natural conditions, and to correlatesome soil properties with the occurrence of these elements. Soil samples from EMBRAPA Soils’ (RJ)collection were used (162 in total), corresponding to A and B (or C) horizons from 81 profiles, of themain classes of Brazilian soils, especially Ultisols (Argissolos) - 27% and Oxisols (Latossolos) - 42%.Heavy metal levels were determined using an ICP-AES, after extraction with acqua regia. Theaverage metal concentrations were below average values reported in the literature for soils foundabroad, with exception to Cd. They were also lower than values considered toxic to plants, includingCd values. Soil samples were clustered by similarity, based on the variables content of clay, silt,Mn, and Fe, and value of soil CEC (T value). This enabled separation of the soil samples in sevengroups which have distinct ranges for the soil variables contents, which allowed an estimation ofthe heavy metals background levels for soil samples with characteristics within the range of each group.

Proposição de valores de referência para a concentração natural de metais pesados em solos brasileiros

Para avaliar a extensao da poluicao de uma area, e comum se comparar os teores totais de metais pesados encontrados num dado solo com aqueles defrontados em condicoes naturais (nao poluidos) ou com valores de referencia (padroes). Propuseram-se atraves deste estudo: 1) valores de referencia (VR) e limites de tolerância (LT) para os mais representativos solos brasileiros, e 2) um modelo para obtencao das concentracoes naturais de Cd, Co, Cr, Cu, Ni, Pb e Zn em um solo, a partir dos teores de silte, argila, Mn, Fe e CTC. Reuniram-se 256 amostras de solo por similaridade, em sete grupos e se calcularam as concentracoes correspondentes ao quartil superior dos dados. Essas concentracoes sao propostas como valores de referencia (VR) em solos brasileiros; alem disso, obtiveram-se os limites de tolerância (LT) para cada grupo a partir da expressao antilog (m + 2s), cujos m (media) e s (desvio padrao) dos dados foram transformados em log10. As funcoes de classificacao da analise discriminante mostraram se apropriadas para alocar novas amostras nos grupos estabelecidos. Assim, e possivel avaliar solos sob atividade antropica e saber se ha motivo para suspeitar de que a area esteja poluida.

Chemical amendment and phytostabilization of an industrial residue contaminated with Zn and Cd

A fitoestabilizacao de solos contaminados com metais pesados e considerada uma boa alternativa para reduzir a erosao e dispersao de contaminantes no ambiente. Foi conduzido um experimento em casa-de-vegetacao com o objetivo de avaliar a contencao quimica (silicato de calcio e lodo do biodigestor de uma cervejaria) e a fitorremediacao pela Brachiaria decumbens, de um residuo industrial contaminado com Zn e Cd, utilizando vasos de 30 L. Os tratamentos foram: residuo industrial (testemunha); residuo industrial + 20% lodo; residuo industrial + silicato de calcio (2%; 3%); (residuo industrial + 20% lodo) + silicato de calcio (2,5%; 4%). Apos estabilizacao do pH, foram cultivados nos tratamentos plantas de B. decumbens, visando avaliar o potencial de tolerância a elevadas concentracoes de Zn e Cd presentes no residuo industrial. No plantio e colheita das plantas foram retiradas amostras dos diferentes tratamentos para determinacao do pH e extracoes simples com agua, nitrato de sodio, acido acetico e DTPA. A partir das concentracoes de Zn e Cd obtidas nas extracoes, foram estimadas, atraves das diferencas nas quantidades extraiveis, as concentracoes de Zn e Cd nas provaveis formas quimicas. A adicao de residuos industriais, alcalino e orgânico, provocou reducao nas percentagens de Zn e Cd nas fracoes soluvel e trocavel, e predominância dos mesmos em fracoes quimicas mais estaveis como complexados e precipitados. A B. decumbens apresentou tolerância ao Zn e Cd presentes no residuo industrial apos tratamento de contencao quimica.

RELAÇÃO ENTRE ADSORÇÃO DE METAIS PESADOS E ATRIBUTOS QUÍMICOS E FÍSICOS DE CLASSES DE SOLO DO BRASIL

Este trabalho objetivou avaliar quais parâmetros obtidos dos modelos de isotermas de Freundlich e Langmuir melhor descrevem a adsorcao de metais pesados em solos intemperizados e identificar a relacao entre os parâmetros selecionados e os atributos quimicos, fisicos e mineralogicos de 12classes de solo do Brasil. Os solos foram coletados pela EMBRAPA-CNPS em diversos levantamentos nas regioes: Sul, Sudeste e Norte do Pais. Avaliou-se, por meio da analise de trilha, o desdobramento do coeficiente de correlacao entre variaveis dependentes, obtidas atraves das isotermas de adsorcao (parâmetros de adsorcao), e variaveis independentes (atributos quimicos e fisicos do solo), bem como os efeitos diretos e indiretos para os elementos Cd, Cu, Pb e Zn. Os atributos do solo: argila, carbono orgânico, capacidade de troca cationica efetiva, ferro extraido pelo citrato ditionito-bicarbonato e aluminio extraido pelo ataque sulfurico foram os que apresentaram maiores coeficientes de correlacao simples com os parâmetros de adsorcao, tendo sido utilizados no modelo da analise de trilha para explicar a adsorcao de metais pesados. A analise de trilha mostrou-se como uma ferramenta importante no estudo do comportamento dos metais pesados no solo. As constantes KF de isotermas de Freudlich e capacidade-tampao maxima (KLb) de Langmuir apresentaram os coeficientes de determinacao mais elevados e os menores valores do efeito da variavel residual para todos os metais estudados. As variaveis que mais contribuiram com a adsorcao de metais pesados foram carbono orgânico, capacidade de troca cationica efetiva, pH, argila e aluminio total.

Estimation of reference values for cadmium, cobalt, chromium, copper, nickel, lead, and zinc in Brazilian soils

Abstract The objectives of this study were 1) to recommend reference values (RVs) and tolerance limits (TLs) for representative Brazilian soils and 2) to propose a model to calculate natural contents of cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) in a soil from the silt, clay, manganese (Mn), iron (Fe), and cation exchange capacity (CEC) values. A set of 256 soil samples was classified by similarity in seven groups, and the concentrations corresponding to the upper quarter of data collected were then calculated. These concentrations are proposed as RVs for Brazilian soils. Additionally, TLs were obtained for each group from the antilog expression (m+2s), where m=mean value and s=standard deviation of data transformed in log10. The classification functions of discriminant analysis proved to be suitable to allocate new samples in the established groups. Thus, it is possible to evaluate soils under anthropic activity and, by comparison with reference values, to be aware of pollution risks in a given area.

Conseqüências de diferentes sistemas de preparo do solo sobre distribuição química e perdas de fósforo de um Argissolo

The research was accomplished in the Caetes watershed, municipal district of Paty do Alferes (RJ), from January to March of 1997, in the crop cycle of cucumber (Cucumis sativus L.). The research took place in an area of Yellow-Red Podzolic soil (Udult), of clayey texture, at a slope of 60%, where Wischmeier plots for studying soil erosion were installed. The treatments applied were: (a) MAQ - down hill mechanical tillage, and burning of crop residues; (b) MANQ - contour mechanical tillage, with plant residues remaining on the field; (c) AA - contour tillage, with animal traction and strips of grasses placed every 7,0 m; and (d) CM - minimum tillage. Soil samples were collected in crop rows, and planting pits, in the plow layer, before planting and after harvesting. After each rain that resulted in production of sediments, the material was collected, dried, weighed, and kept for analyzes of total P; labile, organic and inorganic P; organic carbon; and pH in water. The CM treatment reduced P losses and influenced the distribution of labile and organic forms of P. MAQ treatment implied in loss of 12.4% of the total applied P, while the CM lost only 1%. The remaining of the plant residues among the crop rows, on the MANQ plot, decreased in 40% the total P loss, when compared to MAQ. The plots MAQ and MANQ showed clay increase in the sediments, which favored the highest losses of P sorbed in the clay fraction.

Influência de diferentes manejos agrícolas na distribuição de metais pesados no solo e em plantas de tomate

Paty do Alferes in the State of Rio de Janeiro, Brazil, is a county with agricultural tradition, whose main economical source is horticulture. Topography and rainfall regime of the region are favorable for erosion. Due to the lack of an appropriate soil management, besides excessive application of agrochemicals, physical and chemical soil degradation processes are favored, causing serious environmental impacts. With the objective to evaluate accumulated heavy metals in soil and in tomato plants (Lycopersicon esculentum Mill), raised in different soil tillage systems, a study was carried out in the county of Paty do Alferes (RJ), in the months from August to December 1999. Wischmeier plots of 22.0 x 4.0 m (with runoff and sediment collectors) were installed on a Red-Yellow Latosol with 30 % incline. Each tillage system represented a treatment: (a) conventional tillage: downhill furrows and burning of vegetal residues (PC); (b) tillage along contour lines: contour plowing by animal traction with strips of cropping grass every 7.0 m (PN); (c) minimum tillage: opening of ditches for plants only, under preservation of the vegetal residues (CM). Soil and tomato plant samples were collected for analyses of heavy metal contents, plant productivity and soil fertility. Productivity in the minimum tillage treatment was significantly lower than in the others, although this system benefited the highest soil fertility. It provided the greatest accumulation of heavy metals in the aerial part of the plants as well, and Cu and Zn contents lay above the permitted heavy metal levels in plants. The fruits of all three soil tillage systems presented Pb concentrations near the limits allowed for fresh food.

Volatilização de amônia oriunda de ureia pastilhada com micronutrientes em ambiente controlado

Novas tecnologias com o intuito de minimizar as perdas de N-NH3 por volatilizacao devem ser desenvolvidas para aumentar a eficiencia de uso do N-ureia. A incorporacao de boro e cobre na ureia pode reduzir esses efeitos por meio da inibicao da atividade da urease. O experimento foi conduzido em casa de vegetacao, onde foram aplicados diferentes fertilizantes nitrogenados (ureia pastilhada com e sem boro e cobre, sulfato de amonio, ureia com inibidor da urease NBPT, ureia granulada e ureia revestida com boro e cobre) na superficie de um Planossolo Haplico contido em bandejas (0,1 m2 de area e 10 cm de profundidade), em dose equivalente a 200 kg ha-1 de N. Foram avaliadas as perdas de N-NH3 por volatilizacao durante 18 dias, com o auxilio de um coletor semiaberto. A adicao de cobre e boro no processo de pastilhamento da ureia reduziu as perdas de amonia por volatilizacao em ate 54 %, quando comparado com a ureia granulada comercial, comprovando ser eficiente contra as perdas de N-NH3 por volatilizacao.

Potencial de duas espécies de eucalipto na fitoestabilização de solo contaminado com zinco

With the aim of assessing the phytoremediation process to improve the soil contamination with zinc, it was used Eucalyptus urophylla and Eucalyptus saligna with slag from steelmaking and scales from hot-strip mills. The experiment was conducted in a greenhouse at the Universidade Federal Rural do Rio de Janeiro, using a soil contaminated with zinc, collected in an area near the ore yard at Itaguai harbor as well at the local of disposition of hazardous waste of Mercantil and Industrial Inga Co. at Itaguai-RJ. The substrate was treated with two inertizing agents: industrial waste with alkaline caracteristics (steelmaking slag) in 4 and 6% doses and another one with high content of iron oxide used as adsorption material (hot-strip mill scale) at single dose of 1%. After seedling transplant, the substrate was collected in order to determine pH and zinc fractionation in its different chemicals forms. It was verified that the not treated substrate showed high zinc content in bioavaiable fractions. This caused a reduction in the Zinc concentration in the water-soluble and exchangable forms and increase in more stable phases. The smallest dose of steelmaging slag was sufficient to cause a reduction of zinc concentrations solutions and this effect was showed clearly in the plant development, while the highest dose of steelmaging slag promote higher development in the species. The specie that obtained better development was E./ urophylla, that one showing higher zinc content was E. saligna.

Solubilidade de metais pesados em solos tratados com lodo de esgoto enriquecido

Sewage sludges are nutrient-rich organic materials, thus presenting potential for agricultural use. The use of these materials, however, can be limited by the presence of heavy metals in their composition. This study tried to evaluate: (a) the solubility of Cd, Pb and Zn in soils treated with sewage sludge enriched with these metals; (b) the incubation time effect on distribution changes of Cd, Pb and Zn in their different chemical forms in two soils treated with sewage sludge enriched with these metals; (c) the influence of organic and inorganic sewage sludge fractions on the dynamics of these metals in the soil. A sewage sludge of urban sewer produced in the Station of Treatment of Ilha do Governador the (ETIG), Rio de Janeiro (RJ) was enriched by adding Cd, Pb, and Zn. After 20 incubation days, under constant humidity (50% g g-1), the enriched sewage sludge was used for experiments with two soil samples: Yellow Red Latossol (LV) and Yellow Red Podzolic (PV). In the laboratory, the soil samples were incubated with 0; 20; 40 and 80 t ha-1 of enriched sewage sludge. They were withdrawn after incubation periods of 4, 12, 16 and 160 weeks and analyzed by sequential extraction for their Cd, Pb and Zn contents. Soluble organic compounds were observed to form complexes with cadmium and zinc, maintaining elevated levels of these elements associated to the soluble fraction in water throughout the experiment. Most of the Pb, Cd, and Zn became linked to the hydroxylamine extractable fraction, due to the incorporation of inorganic Fe and Mn from the sewage sludge. Increasing incubation time caused a reduction of this fraction and an increase of the residual fraction, indicating a reduction in the solubility of these elements with time, thus diminishing contamination risks.