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Search Results: 1 - 10 of 25498 matches for " Amaral-Sobrinho Nelson Moura Brasil do "
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Concentra es naturais de metais pesados em algumas classes de solos brasileiros
Fadigas Francisco de Souza,Amaral-Sobrinho Nelson Moura Brasil do,Mazur Nelson,Anjos Lúcia Helena Cunha dos
Bragantia , 2002,
Abstract: No Brasil ainda n o foram definidos os níveis de referência de metais pesados, para avalia o da contamina o do solo. Objetivou-se com este trabalho caracterizar diversos solos brasileiros, em condi es naturais, quanto aos teores totais dos metais pesados Cd, Cr, Cu, Fe, Mn, Ni, Zn e correlacionar algumas propriedades do solo com a ocorrência desses elementos. Utilizaram-se 162 amostras de solo, da soloteca da Embrapa Solos (RJ), correspondendo aos horizontes A e B de 81 perfis, das principais classes de solos brasileiros, especialmente os Argissolos (27%) e Latossolos (42%). Os teores totais de metais pesados extraídos com água-régia foram analisados em ICP-AES. à exce o do cádmio, as concentra es médias dos metais estudados foram, em geral, inferiores aos valores médios encontrados na literatura internacional, e inferiores aos valores desses metais considerados tóxicos para as plantas. As amostras de solo foram agrupadas por semelhan a, utilizandose como variáveis os conteúdos de argila, silte, Mn e Fe e CTC (T). Estabeleceram-se as faixas de concentra es das variáveis de solos nos diversos grupos e uma aproxima o dos teores naturais dos metais pesados para outras amostras de solos com características similares às de cada grupo.
Concentra??es naturais de metais pesados em algumas classes de solos brasileiros
Fadigas, Francisco de Souza;Amaral-Sobrinho, Nelson Moura Brasil do;Mazur, Nelson;Anjos, Lúcia Helena Cunha dos;Freixo, Alessandra Alexandre;
Bragantia , 2002, DOI: 10.1590/S0006-87052002000200008
Abstract: the heavy metals background levels for evaluation of a possible contamination are still not defined in brazilian soils. the objective of this study was to measure the content of the heavy metals cd, cr, cu, fe, mn, ni, zn, in several brazilian soils, under natural conditions, and to correlate some 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 the main classes of brazilian soils, especially ultisols (argissolos) 27% and oxisols (latossolos) 42%. heavy metal levels were determined using an icpaes, after extraction with acqua regia. the average metal concentrations were below average values reported in the literature for soils found abroad, with exception to cd. they were also lower than values considered toxic to plants, including cd 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 seven groups which have distinct ranges for the soil variables contents, which allowed an estimation of the heavy metals background levels for soil samples with characteristics within the range of each group.
Soil preparation and nutrient losses by erosion in the culture cucumber
Amaral Sobrinho, Nelson Moura Brasil do;Mazur, Nelson;
Scientia Agricola , 2005, DOI: 10.1590/S0103-90162005000600010
Abstract: minimum tillage reportedly reduce erosion, avoid soil degradation and improve crop productivity. this study aimed to determine how tillage operations may affect either nutrient accumulation or nutrient losses by erosion. the study was, carried out from december, 2000 to march, 2001, in the watershed of the caetés river, in rio de janeiro state, brazil (22o25'43"s, 43o25'07"w). the experiment was set up in sandy clay kandiudult soil, 60% slope, under cucumber (cucumis sativus l.) crop. soil samples were collected before planting and after harvest, on 22.0 x 4.0 m greeoff plots. after each rainfall, fine sediments carried by runoff were deposited into two collecting tanks in a row, installed at the end of each plot, and were later dried, weighed and stored for analyses. treatments (n = 4) were characterized by different tillage systems: (i) downhill plowing followed by the burning of crop residues (dpb); (ii) downhill plowing with no burning of the crop residues (dpnb); (iii) animal traction contour plowing, with strips of guinea grass planted at a spacing of 7.0 m (at); and (iv) minimum tillage (mt). samples of the soil-plowed layer were collected before planting and after harvest, between the rows and from the plants. total concentration of ca, mg, k and p were determined after extraction with nitric perchloride digestion. labile p and exchangeable k were extracted with the mehlich 1 extractant solution. the mt system reduced losses of both exchangeable bases (15%) and p (8%), and affected the distribution of labile and organic p. crop residues left on soil surface in the mt system, resulted in increased organic matter content. downhill plowing, the most used tillage operation in the region, resulted in the greatest losses of ca, mg, k, and p.
Soil preparation and nutrient losses by erosion in the culture cucumber
Amaral Sobrinho Nelson Moura Brasil do,Mazur Nelson
Scientia Agricola , 2005,
Abstract: Minimum tillage reportedly reduce erosion, avoid soil degradation and improve crop productivity. This study aimed to determine how tillage operations may affect either nutrient accumulation or nutrient losses by erosion. The study was, carried out from December, 2000 to March, 2001, in the watershed of the Caetés River, in Rio de Janeiro State, Brazil (22o25'43"S, 43o25'07"W). The experiment was set up in sandy clay Kandiudult soil, 60% slope, under cucumber (Cucumis sativus L.) crop. Soil samples were collected before planting and after harvest, on 22.0 X 4.0 m Greeoff plots. After each rainfall, fine sediments carried by runoff were deposited into two collecting tanks in a row, installed at the end of each plot, and were later dried, weighed and stored for analyses. Treatments (n = 4) were characterized by different tillage systems: (i) downhill plowing followed by the burning of crop residues (DPB); (ii) downhill plowing with no burning of the crop residues (DPNB); (iii) animal traction contour plowing, with strips of guinea grass planted at a spacing of 7.0 m (AT); and (iv) minimum tillage (MT). Samples of the soil-plowed layer were collected before planting and after harvest, between the rows and from the plants. Total concentration of Ca, Mg, K and P were determined after extraction with nitric perchloride digestion. Labile P and exchangeable K were extracted with the Mehlich 1 extractant solution. The MT system reduced losses of both exchangeable bases (15%) and P (8%), and affected the distribution of labile and organic P. Crop residues left on soil surface in the MT system, resulted in increased organic matter content. Downhill plowing, the most used tillage operation in the region, resulted in the greatest losses of Ca, Mg, K, and P.
Conseqüências de diferentes sistemas de preparo do solo sobre distribui??o química e perdas de fósforo de um Argissolo
Villareal Nú?ez, Jose Ezequiel;Amaral Sobrinho, Nelson Moura Brasil do;Mazur, Nelson;
Bragantia , 2003, DOI: 10.1590/S0006-87052003000100013
Abstract: the research was accomplished in the caetés 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.
Efeito do composto de resíduo sólido urbano no teor de metais pesados em solo e goiabeira
Collier, Leonardo Santos;Amaral Sobrinho, Nelson Moura Brasil do;Mazur, Nelson;Velloso, Ary Carlos Xavier;
Bragantia , 2004, DOI: 10.1590/S0006-87052004000300011
Abstract: the work was performed in the municipal district of cachoeiras de macacu, rio de janeiro state and had as objective to obtain information on the contents of chemical forms of cu, cr, mn, ni, pb and zn in soil gleissolo pouco húmico treated with composted urban residues, and the concentrations in the leaves and fruits of guava (psidium guajava l.). three areas with different land use history were used: area that received doses of 40 t.ha1 of composted of urban solid residue (crsu) in the surface for eleven consecutive years; area with only one application of crsu in the hole; and control area, with no guava and no crsu. the soil samples were taken from each area, in the layers of 05, 515 and 15-30 cm. the sequential extraction of metals from the earth samples demonstrated a widespread tendency of reduction in the mobile or more bioavailable forms of heavy metals in the soil with the use of crsu. there was increase in the heavy metals contents in the leaves and fruits of guava cultivated in areas that received crsu. however, these contents were within the normal range for economic crops. there is a need for monitoring total metal contents, in soils and plants, due to their increment in soils treated with crsu.
Sistemas de preparo de solo e acúmulo de metais pesados no solo e na cultura do piment?o (Capsicum Annum L.)
Nú?ez, José Ezequiel Villarreal;Amaral Sobrinho, Nelson Moura Brasil do;Mazur, Nelson;
Ciência Rural , 2006, DOI: 10.1590/S0103-84782006000100017
Abstract: the objectives of this study were to determine the influence of different soil tillage methods on the loss of heavy metals by erosion, and to evaluate the level of contamination of soil and food in paty do alferes county, state of rio de janeiro, brazil. the experiment was conducted from december of 1999 to march of 2000, and pepper (capsicum annuum l.) was the cultivated crop. four wichmeier plots were installed, with an area of 22 x 4m. the treatments utilized were the following: (i) tillage with machinery and operation down hill and burning of the grassland (maq); (ii) tillage with machinery and operation down and without burning of grassland between lines of crop (manq); (iii) tillage with animal traction and following the natural contour of the hill, strip cropping grass each 7m (aa); and minimum tillage, (cm). the highest losses of heavy metals by erosion were in the maq treatment. the minimum tillage showed greater accumulation of heavy metals than others soil tillage methods, due to lower erosion losses in this trial. the concentration of pb in fruits in natura, in the four soil tillage methods, was above the levels allowed to food consumption. the results obtained in this work allow to conclude that the intensive use of agrochemistrys associated the high soil losses by erosion can determine serious risks of contamination of soil, water and foods.
Efeitos da aplica??o do lodo de esgoto enriquecido com cádmio e zinco na cultura do arroz
Oliveira, Clarice de;Amaral Sobrinho, Nelson Moura Brasil do;Marques, Valter dos Santos;Mazur, Nelson;
Revista Brasileira de Ciência do Solo , 2005, DOI: 10.1590/S0100-06832005000100012
Abstract: the presence of heavy metals can restrict the use of sewage sludge as a source for plant nutrients since they may contaminate soil, aquifers and plants. urban sewage sludge from the treatment station of ilha do governador (etig), rio de janeiro, brazil, was enriched with 1.667 mg kg-1 cd and 8.000 mg kg-1 zn. after 20 days of incubation under a constant humidity of 50% (g g-1), doses of 0, 20, 40 and 80 t ha-1 were applied to two soil samples (red-yellow latosol (lv) and red-yellow argisol (pv)). a greenhouse experiment evaluated the effect of cd and zn on the growth of rice (iac-47) during 126 days in the samples of both soils incubated with the enriched sewage sludge. a complete randomized block design was used with four replications. plant roots, straw and grains and their respective biomass (dry matter) and cd and zn concentrations were evaluated at harvest. the high cd and zn doses applied to the soil did not affect plant growth but the plant roots showed high cd and zn concentrations as a consequence of the low transference of these elements to the spoots. the cd and zn levels found in the whole plant demonstrate a high tolerance of the rice variety iac-47 to these elements.
Geoquímica de radionuclídeos naturais em solos de áreas circunvizinhas a uma Unidade de Minera??o e Atividade de Uranio
Cardoso, Gildevan Viana;Amaral Sobrinho, Nelson Moura Brasil do;Wasserman, Maria Angélica Vergara;Mazur, Nelson;
Revista Brasileira de Ciência do Solo , 2009, DOI: 10.1590/S0100-06832009000600040
Abstract: the environmental impacts resulting from uranium exploration and processing are to a great extent identical to those caused by extractive mining activities in general. this study aimed to determine the geochemical partitioning of the natural radionuclides 238u, 226ra and 210pb in areas surrounding the uranium mining and concentration plant (ura) of the brazilian nuclear industries s.a., in the uranium deposit region of lagoa real, in caetité, southwestern bahia state. representative soil samples of the main regional soil classes were collected from the layer 0-20 cm, in five areas around the ura. the level of total activity and geochemical fractionation (f1slightly acidic, f2 reducible, f3 oxidisable, f4 alkaline, and f5 residual) were determined for the five areas. the average total radioactivity levels were, in bq kg-1 soil: 50 for 238u, 51 for 226ra, and 159 for 210pb. during the potentially bioavailable phase (f1) 11 % were extracted for 238u, 13 % for 226ra and 3 % for 210pb. the bioavailability of 238u was higher in more acidic soils and the affinity for iron oxides was greater, unlike in the case of 226ra, with the greatest bioavailability. 210pb was predominantly associated with f5. the high percentage of 238u, 226ra and 210pb in the geochemical fraction f5 indicates that the concentrations observed in the five soils are predominantly associated to the parent material of these soils, rather than to an artificial contamination caused by the ura activity.
Background levels of some trace elements in weathered soils from the Brazilian Northern region
Fadigas, Francisco Souza;Amaral Sobrinho, Nelson Moura Brasil do;Anjos, Lucia Helena Cunha dos;Mazur, Nelson;
Scientia Agricola , 2010, DOI: 10.1590/S0103-90162010000100008
Abstract: soils formed from the barreiras group sediments, located mainly along the coast of brazil northern and northeastern regions, generally present low concentrations of iron oxides and total organic carbon, high quantities of quartz in the sand fraction, and kaolinitic clay mineralogy. the objective of the present study was to quantify the pseudo total concentrations of cd, co, cu, cr, mn, ni, zn and fe in xhantic udox and xhantic udult soils derived from these sediments. the reference sites were covered by native vegetation and located in the states of pará and amapá, brazil. multiple linear regression analysis was applied to determine correlations between soil parameters and the levels of these metals. the best correlation was obtained between fe, mn, clay, and silt contents, and cd, co, cu, zn, cr, ni. a correlation between ph and these metal levels was not found. clay and sand contents showed a negative inverse correlation with the metal levels,of same magnitude but with a different sign; this was the reason for excluding one of the parameters in the regression model. in general, the contents of the elements were lower than those found in soils formed from other parent materials. the mn content was included in the model of multiple linear regression for cd and co, due to its association with these last metals. silt level showed to have a significant influence in the equations for cr and co, which is attributed to the presence of clay minerals and fe and mn oxides in ferruginous and clay aggregates of silt size. the equations obtained in this paper, are useful to predict, in general terms, the amounts of those heavy metals in an unknown soil sample, if the soil material were not contaminated or affected by land usage. thus, they may be applied to evaluate soil contamination by the studied heavy metals.
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