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Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objetivou-se avaliar as características físicas de quatro rações comerciais (B, M, N e S) obtidas de dezesseis propriedades piscícolas, categoria engorda com 28% de proteína bruta. Foram avaliados resistência física (RF), lixiviação da matéria seca (LMS), tempo máximo de flutuação (TMF), tempo máximo de impermeabilização (TMI), tempo de turgidez máxima (TTM), tempo máximo de agregação (TMA), granulometria (GRA) e uniformidade (UNI). Observou-se que, para RF, TMI, TTM e LMS as rações não diferiram (P>0,05) e os valores variaram de 96,9 a 98,6%; 4,50 a 240,0 segundos (s); 180,0 a 930,0s e 7,4 a 10,1%, respectivamente. Para TMF, TMA, GRA e UNI verificou-se diferença entre as rações (P

RESUMO A companhia Siderúrgica Nacional (CSN) vem desenvolvendo estudos para disposição adequada dos seus resíduos no Aterro de Resíduos Sólidos Industriais (ARSI). Com objetivo de avaliara movimentação de Pb, Zn, Ni e Cd provenientes das misturas de resíduos alcalinos e ácidos da CSN, amostras dessas misturas foram colocadas sobre as amostras de solo empacotadas, em colunas de vidro, na proporção 1:4 (resíduo:solo). Após a lixiviação com 50 volumes-poro, as colunas foram seccionadas em quatro partes iguais e os teores de Pb, Zn, Ni e Cd determinados em todas profundidades. O pH do resíduo alcalino resultou na diminuição da vazão nas colunas, na baixa solubilidade do Pb do resíduo e na retenção do Zn, Ni e Cd na camada superficial de 0-5cm. Entretanto, no resíduo ácido a mobilização desses metais foi muito superior à do resíduo alcalino, sendo, inclusive, detectados no efluente em concentrações superiores ao permitido pela FEEMA.

Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Automotive catalysts represent a secondary source for precious metals recovery. These elements are usually obtained from minerals. Recently, methods have been sought to recover them from waste materials. The main route consists of pyrometallurgical treatments at high temperatures with the generation of other pollutants and very high energy consumption. With hydrometallurgy, routes can be developed which favor the aqueous extraction of said elements at room temperature. In an automotive catalyst, there are different metals which can interfere in the recovery process. In this study, sodium citrate (Na3C6H5O7•H2O), nitric acid (HNO3), and hydrochloric acid (HCl) were evaluated as a hydrometallurgical pretreatment to dissolve Fe, Zn, and Pb contained in a spent automotive catalyst and to improve the subsequent extraction of the precious metals contained therein (Au, Ag, and Pt). Afterwards, the aqueous extraction of precious elements with thiourea (SC(NH2)2) was carried out, comparing the effect of the pretreatment reagents. Finally, the feasibility and effect of each pretreatment as a route for precious metals recovery were analyzed with the aim to avoid processes at high temperatures. [ABSTRACT FROM AUTHOR]

Copyright of Engenharia na Agricultura is the property of Engenharia na Agricultura and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tecno-Lógica is the property of Tecno-Logica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Brazil has the second largest reserve of monazite, which is one of the three main minerals bearing of rare earth elements. In this study, a monazite concentrate, derived from the occurrence of heavy minerals in the coastal strips of the states of Bahia and Espírito Santos, was used. The best way to analyze aqueous solutions rich in rare earths by ICP-OES was also evaluated. In this work, the steps used to obtain an aqueous solution rich in rare earths from the monazite concentrate involved the following steps: addition of NaOH to the concentrate, heating at 400 °C for 3 hours, washing with water and subsequent leaching of the remaining solid phase with HCl. Chemical and mineralogical characterizations were accomplished on the products of this process and the results indicated that the initial concentrate is rich in light rare earths, the alkaline fusion product is predominantly composed of rare earth hydroxides and free of NaOH. The acid leaching tailings showed to be rich in zirconite, indicating that the dissolution of the rare earth hydroxides formed in the previous step was complete. Spectral interferences in the lines of the predominant elements were considered in the ICP-OES analysis using individual patterns of these elements. The following lines were defined for the predominant elements: Ce 456.236 nm, Th 283.730 nm, La 384.902 nm, Nd 430.058 nm, Pr 390.844 nm, and Sm 428,079 nm. The leachate obtained after acid leaching of rare earth hydroxides was analyzed by this method and the concentrations of the predominant elements (in g/L) were: Ce 32.81, Th 14.76, La 8.58, Nd 3.35, Pr 3.02, and Sm 1.28. [ABSTRACT FROM AUTHOR]

Copyright of Revista Caatinga is the property of Revista Caatinga and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Ciência Agronômica is the property of Revista Ciencia Agronomica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Nativa is the property of Revista Nativa and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A serapilheira é indicadora da integridade de ecossistemas florestais quando analisamos sob a perspectiva das “Formas de Humus”. Sendo o material orgânico disposto em camadas internas que variam no peso e espessura e expressa a ciclagem de nutrientes, que sintetiza o funcionamento dos ecossistemas. A pesquisa propõe entender que nutrientes são liberados pela ação da chuva lixiviando o material orgânico na copa e no solo, bem como pelas camadas internas da serapilheira numa floresta urbana de clima tropical. Foram construídos pluviômetros experimentais que coletavam a chuva e a depositava em recipientes abaixo de cada camada de serapilheira para análise química. Como resultados, percebemos que as diferentes camadas vão nutrir o solo de maneira diferenciada quando esse processo acontece com formas de humus mull-moder. O cálcio é liberado em maior quantidade pelas camadas F e MFB, o potássio e o magnésio têm maior disponibilização pela camada L, indicando que durante esse processo esses nutrientes são mais consumidos do que liberados. O sódio é abundante nas chuvas antes de atingir a serapilheira.

The present work studied the solid-liquid extraction of the flavonoid quercetin from purple onion. Experimental studies of solvent, temperature, raw material mass per solvent volume and extraction time showed the best condition for leaching: ethanol 60% (v/v); 40°C; raw material mass (g)/solvent volume (ml) 1:10; 2 hours and 200 rpm shaking; with a quercetin recovery of 209.83 mgquercetin/graw material and 335.19 mgquercetin/gSST (Total Solid Soluble). With these values the complete extraction process was simulated with the aid of Aspen Plus® software. Starting from a base of calculation of 1000 kg/day of raw material it was obtained a production of 21.7 kg/day of quercetin, in the form of alcoholic extract 40 °BRIX. An ethanol recycle of 788.2 kg/day was estimated, requiring 17.8 kg/day of anhydrous ethanol and 94.3 kg/day of water in the process.

O objetivo desta pesquisa foi avaliar como o manejo da adubação nitrogenada em cobertura no milho e os volumes de irrigação afetam a dinâmica do nitrogênio no perfil do solo e o rendimento de grãos de milho. Para isso, foi avaliada uma área experimental que vem sendo cultivada em sistema plantio direto há 22 anos. Os tratamentos constaram da combinação de manejos de nitrogênio em cobertura (testemunha sem nitrogênio em cobertura, dose única de 300 kg ha-1 e essa dose parcelada em duas vezes) e volumes de irrigação (20 e 100 mm). As amostragens de solo foram realizadas dez dias após a primeira adubação de N em cobertura e dez dias após a segunda adubação de nitrogênio em cobertura. Independentemente do volume, a irrigação promoveu o aumento nos teores de nitrato nas camadas subsuperficiais (20-30 e 30-40 cm) após a aplicação das doses de nitrogênio em cobertura. O parcelamento da adubação nitrogenada foi uma alternativa eficiente para diminuir os teores de nitrato nas camadas subsuperficiais do solo, para ambos os volumes de irrigação. Entretanto, isso não se refletiu em ganho de produtividade e em retorno econômico quando comparado à aplicação única de nitrogênio em cobertura, independentemente do volume de irrigação.

Copyright of Ceramica is the property of Associacao Brasileira de Ceramica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

One of the challenges of aquaculture is to develop efficient technology packages for different species with zootechnical potential. Several researchers have been studying the stability of macrodietes in water, since leaching processes happen quickly, causing nutrients to be released into the water, leading to pellet disaggregation and, consequently, decreasing the availability of capture of farmed animals. The objective of this work was to show the effect of the sodium alginate crosslinking process, as well as to evaluate the influence of this step on the resistance of commercial feed to leaching processes. The coating was performed by immersing the commercial feed pellets in a sodium alginate solution, followed by the crosslinking process in calcium chloride solution. The methodology employed in pellet coating proved to be very efficient and easy to apply. Determinations of nitrogen and phosphorus concentrations in water samples decreased for treatments using coated commercial diets, this factor may lead to the maintenance of physical chemical parameters of water quality. The proposed methodology may be an alternative in the production of feed aiming at a greater stability of the pellets and water of the farming system. [ABSTRACT FROM AUTHOR]

Copyright of Ceramica is the property of Associacao Brasileira de Ceramica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plaster is a very useful material in construction, but it is responsible for producing waste in the manufacturing process and also the demolition works. This work seeks alternatives that reduce the production of waste in the manufacturing process using plaster additives in their composition and also to assess the damage caused by improper disposal of waste produced in buildings demolition, due to its possible use in fish farms. Different modified plasters were evaluated on various parameters such as cure time, appearance, resistance and morphological changes. The modified plasters with diatomaceous earth show good results. Waste of plaster and pure plaster were submitted to leaching tests at different pH values to evaluate its behavior in two different periods of time. It was analyzed parameters such as conductivity, turbidity and calcium contents in the leached samples, checking that the plaster and your residue influence the aquatic environment. It was found that pH, conductivity and turbidity are altered when subjected to gypsum concentrations.

The batteries convert chemical energy into electrical energy and are responsible for the operation of laptops, watches, telephones, calculators, radios and cardiac pacemakers. Alkaline cells, which are known in the art as having an inorganic base, are composed of a porous zinc anode immersed in an alkaline solution of potassium hydroxide or sodium hydroxide, and of a cathode of compacted manganese dioxide. The objective of this study was to perform physical-chemical analyzes (pH, conductivity, real color and turbidity) in three different types of batteries (alkaline and two zinc manganese) and to identify the presence of certain metals such as cadmium, lead, iron, manganese, zinc and potassium through a leaching test. The composition of the cells was also quantified and qualified by means of instrumental analyzes using X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) technique. The values found were compared with the current legislation (CONAMA, Resolution 401/2008, resolution 430/2011) where it was found that the pH, turbidity, real color, iron, manganese and zinc parameters exceeded the legal limits while the values of metals cadmium and lead have met the limits proposed by the legislation. In this way, it is fundamental that there is awareness of the society and monitoring of the responsible bodies regarding the correct disposal of the batteries, avoiding future problems, since the same ones in contact with a water course, can entail in complications to the environment. [ABSTRACT FROM AUTHOR]

Rare Earth Elements are a group of chemical elements that include all elements of the group of lanthanides, in addition to yttrium and scandium. Due to their chemical and physical properties, Rare Earth Elements play an essential role in the high-tech product industry, making the availability of these elements extremely important for technological advancement, directly linked to the country's economy. Rare Earth Elements are found in several minerals, mainly monazite, bastnasite, xenotime and ionic adsorption clays. Due to the occurrence of the phenomenon of lanthanide contraction, the Rare Earths have great chemical and physical similarity, resulting in the difficulty of separating and obtaining the lanthanide elements in the individual form. One of the great challenges of the production chain of Rare Earth Elements is the search for new methods of extraction economically viable without harm to the environment. This bibliographical review intends to approach the mineralogical and chemical aspects of different minerals bearing Rare Earth Elements and to discuss the technological challenges in the extraction processes of these elements, focusing on the use of green technologies to compose the production chain of Rare Earth Elements. [ABSTRACT FROM AUTHOR]

Gypsum utilization is a critical practice in agriculture because of the high solubility and consequent relative neutralization of subsurface toxic aluminum. However, it has been observed that in most cases, gypsum is being randomly utilized without scientifically established parameters or even the need to use it as a soil amendment at all. The objective of this study was to evaluate the chemical composition and electrical conductivity of an Oxisol’s saturation extract under different gypsum doses (0, 1.0, 2.0, 4.0, and 8.0 Mg ha-1). This experiment was conducted in a greenhouse environment. Soil columns (V = 1.57 dm3) were filled with sifted (2 mm) soil collected from the upper layer (0-20 cm). The experimental design adopted was completely randomized with five repetitions. The treatments consisted of a 5 × 2 factorial through five gypsum doses (0.0, 1.0, 2.0, 4.0, and 8.0 Mg ha-1 of gypsum consisting of 224.1 g kg-1 S, 314.8 g kg-1 CaO, and 7 g kg-1 P2O5) and two depth evaluations (0-10 and 10-20 cm). After the treatments, soil from both 0-10 cm and 10-20 cm layers was removed from the columns, sifted once (2 mm), and subjected to vacuum extraction to assess the saturation extract. The data acquired was processed and submitted to variance analysis (when due) and adjusted to regression equations when statistically relevant. Significant increases were observed for Ca, Mg, K, P, and S, although Al, Si, and pH presented no statistically significant difference. The electrical conductivity value of this soil in particular is directly related to the gypsum dose.

Resumo O objetivo deste trabalho foi determinar a movimentação vertical do íon potássio em perfil de Neossolo Quartzarênico cultivado com cana-de-açúcar. Foram realizados dois experimentos, em campo. O primeiro consistiu de uma avaliação da movimentação do íon no perfil do solo até 1,80 m de profundidade, por dois anos, em uma área cultivada com cana-de-açúcar e em outra sob cerrado. O segundo consistiu da avaliação do movimento do íon até a profundidade de 1,00 m, sob dois regimes hídricos: natural e controlado. No experimento sob condições controladas, as avaliações foram feitas em parcelas de 0,5 m2, delimitadas por chapas galvanizadas, com adição de 80 kg ha-1 de K2O seguida da adição de 1.200 mm de água. A área sob lavoura apresentou maior conteúdo de matéria orgânica do solo, maior pH e, consequentemente, maior capacidade de retenção do K+ nas camada superficiais do perfil do que a área de cerrado. Além disso, na área sob lavoura, a avaliação da disponibilidade de K+ ao longo do perfil do Neossolo avaliado foi influenciada pelo tipo de regime hídrico adotado (chuva natural ou controlada). Independentemente do uso do solo, o K+ apresenta rápida movimentação no perfil do solo.

ABSTRACT The aim of this work was to evaluate the change in electrical conductivity and pH of a soil solution and its composition, with regard to the levels of nitrate and potassium, in a Latosol cultivated with pineapple and subjected to applications of different levels of vinasse. The experiment was conducted in a greenhouse at the Department of Biosystems Engineering of ESALQ/USP. The treatments comprised the application of five levels of vinasse: T1 - 0 m3 ha-1, T2 - 231 m3 ha-1, T3 - 347 m3 ha-1, T4 - 462 m3 ha-1, and T5 - 578 m3 ha-1. Application was every 20 days, using a localised irrigation system with emitters having a nominal flow rate of 4 L h-1 and spaced 0.40 m apart. The applied doses of vinasse were calculated by following the recommendations of CETESB standard P4.231, so that treatment T4 would supply the demand of the pineapple plant for potassium. The solution was collected by means of porous capsule extractors at 30, 120 and 210 days from the start of vinasse application. It was found that increases in the volume of the applied levels resulted in greater values for the electrical conductivity of the soil (ECs) and in the concentration of potassium (K) and nitrate (NO3), with higher values being obtained in the 0.20 m layer. The results demonstrated that pH decreased with increases in the vinasse being applied.

This research work was carried out with the aim of obtaining an alternative route for the leaching of low grade gold ores for an industrial plant which currently employs the Carbon in Leaching process in Uruguay. Bottle roll tests were performed in bottlers of 20 liters and columns of 3 meters to set some parameters, operating criteria and design that enables up the implementation of an industrial plant of leaching using dynamic stacks of up to 4 meters high to treat about 1,000,000 tons of low grade gold ore per year with an average gold content of 0.65 grams per ton of ore and operating with a particle size of 80 percent less than 12.67 mm. The operation time is 3 years reaching an annual output of 455 kilograms of gold. https://doi.org/10.18540/2446941602022016029

ABSTRACT Soils of tropical regions are more weathered and in need of conservation managements to maintain and improve the quality of its components. The objective of this study was to evaluate the availability of K, the organic matter content and the stock of total carbon of an Argisol after vinasse application and manual and mechanized harvesting of burnt and raw sugarcane, in western São Paulo.The data collection was done in the 2012/2013 harvest, in a bioenergy company in Presidente Prudente/SP. The research was arranged out following a split-plot scheme in a 5x5 factorial design, characterized by four management systems: without vinasse application and harvest without burning; with vinasse application and harvest without burning; with vinasse application and harvest after burning; without vinasse application and harvest after burning; plus native forest, and five soil sampling depths (0-10 10-20, 20-30, 30-40, 40-50 cm), with four replications. In each treatment, the K content in the soil and accumulated in the remaining dry biomass in the area, the levels of organic matter, organic carbon and soil carbon stock were determined. The mean values were compared by Tukey test. The vinasse application associated with the harvest without burning increased the K content in soil layers up to 40 cm deep. The managements without vinasse application and manual harvest after burning, and without vinasse application with mechanical harvesting without burning did not increase the levels of organic matter, organic carbon and stock of total soil organic carbon, while the vinasse application and harvest after burning and without burning increased the levels of these attributes in the depth of 0-10 cm.

RESUMO O objetivo desse trabalho foi avaliar a atividade alelopática dos lixiviados das raízes e folhas secas de Asemeia extraaxillaris sobre o crescimento de corda de viola Ipomoea cordifolia em casa de vegetação, para avaliação dos efeitos sobre o estresse oxidativo. Nos bioensaios foram utilizadas três concentrações (0,25 - 5,00 e 10,00 g) e um controle, com quatro repetições de 10 plantas, cultivadas em solo durante 30 dias. Os lixiviados possuem ação alelopática e o maior efeito foi verificado para o pó das raizes. O efeito inibitório foi dose-dependente e o aumento do estresse oxidativo foi observado pelos níveis da catalase, peroxidase, superóxido dismutase, glutationa redutase, peroxidação lipídica e síntese de formazan. Concluiu-se que A. extraaxillaris possui substâncias capazes de afetar a emergência, o crescimento e o estresse oxidativo de I. cordifolia.

The objective of the present work was to determine the mobility of flumioxazin in Argisol, as a function of two pluviometric indices, as well as possible influences of the chemical and physical properties, on the action of the herbicide. 32 PVC tubes were used (10 cm in diameter by 50 cm in height). These containers were completely filled with the Argisol collected in the arable layer of an area where there was no herbicide application. Once the flumioxazin (50 g i.a. in 200 L/ha) was applied, the treatments were applied. Then, rainfall of 10 mm per day was simulated to reach the desired levels of rainfall (40 and 80 mm), so that the tubes were dismantled and 5 sorghum seeds (Sorghum bicolor) were seeded each depth (2.5; 5; 10; 15 and 30 cm) in the profile of the tubes. These were maintained for 15 days under field conditions to carry out the initial evaluation. Height, dry matter, and phytointoxication were evaluated to analyze possible changes that could be characterized as herbicide effects. Under experimental conditions, flumioxazin was sparingly mobile, remaining in the superficial layer (2.5 cm). [ABSTRACT FROM AUTHOR]

Batteries are electrochemical devices widely used in the modern world. However, its disposal cannot be done in ordinary waste due to the characteristics of corrosiveness, toxicity and reactivity. Although there are laws that establish an adequate destination, this is not always available in all cities in the country. In this sense, this article aims to present a project of recycling commercial batteries with the university-school interaction in the critical aspect of Environmental Education, culminating in the elaboration of a procedural recycling guide. In this project, the batteries were obtained in public schools in Gurupi - Tocantins, after holding lectures to promote environmental awareness on the subject. Then they were opened and the components of zinc and electrolytic pulp were separated and treated by leaching and precipitation methods to the formation of zinc oxide, zinc hydroxide, zinc chloride and manganese oxide which offer less risk to the environment. By means of thermal analysis and X-ray diffraction it was possible to characterize the synthesized products, identifying the composition and the purity of the compounds, evidencing the components recovery of the collected cells. Such results converge with the principles of Critical Environmental Education, in which the participation of society is important to develop an environmental awareness about a local environmental problem that is forgotten in the municipality. [ABSTRACT FROM AUTHOR]

The leaching operation is to put in contact enough water with ground manioc to extract the starch and separate it from the fiber and other components. With the objective of determining the optimal conditions of water consumption in the stage of leaching of cassava was obtained a starch extraction (cassava pulp - water) equilibrium curve. The excessive use of water does not warrant the extraction of starch in this process and increases the cost of this. Quantities of pulp-water were mixed for a residence time of 5 s at 37°C, and refining through a mesh of 120 mesh; to then calculate the composition in water, starch and inert. The results obtained allow optimum relationship of 450 kg to 740 kg of water per 1 kg of cassava pulp with a percentage between the 18 and 20% of removable starch. With the optimization it was possible to reduce the consumption of 3 to 4 kg of water per 1 kg of cassava pulp. [ABSTRACT FROM AUTHOR]

Copyright of Revista ION is the property of Universidad Industrial de Santander and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ceramica is the property of Associacao Brasileira de Ceramica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A preocupação com o destino de produtos químicos e água, aplicados ao solo, tem motivado vários pesquisadores a desenvolverem e aplicarem modelos teóricos, a fim de descrever os processos físicos envolvidos no transporte desses produtos no perfil do solo. Nesse sentido, esta pesquisa teve como objetivo aplicar o modelo HYDRUS-1D, bem como avaliar sua performance, em simulações do deslocamento do potássio e água (umidade do solo), em colunas segmentadas, preenchidas com dois tipos de solos tropicais, em condições não saturadas (Latossolo Vermelho- - Amarelo e Nitossolo Vermelho). Os parâmetros de transporte do potássio foram obtidos por meio de curvas de distribuição de efluentes (Breakthrough Curves (BTC)). O desempenho do modelo foi avaliado com base nos seguintes parâmetros estatísticos: erro máximo, erro absoluto médio, raiz quadrada do erro médio normalizado, coeficiente de massa residual, coeficiente de determinação, eficiência e índice de concordância de Willmott. Diante dos resultados obtidos, pôde-se concluir que o modelo HYDRUS-1D foi eficiente nas simulações de deslocamento do potássio e da água, em relação aos dois materiais de solo estudados.

There has been an urgent need to assess pesticide environmental behavior under Brazilian field conditions and to evaluate the risks associated to its use in agriculture. Besides a qualitative and quantitative interpretation of field experiments to acquire understanding about pesticide environmental behaviour, field experiments are important to test pesticide fate models. Environmental behaviour of fipronil and sulfentrazone in a sugarcane area in Dourados, MS, was evaluated until 257 days after application. Moreover, the PEARL model was tested to simulate the fate of these two pesticides in the field. Soil samples for pesticide residue quantification and water content were taken at 0-10, 10-30, 30-50, 50-70 and 70-100 cm depth. There was a fast dissipation of both pesticides at soil surface within 15 days after application and their leaching was not beyond 30 cm depth. Dissipation and leaching satisfactory simulations for both pesticides were achieved only after calibration of half-life values or using a reduced initial dose. This study shows that fast dissipation of pesticides in the field can be an important process to consider when assessing the environmental behavior of pesticides in Brazil.

A fim de prever o potencial de lixiviação e degradação de um herbicida, bem como a eficiência no controle das plantas daninhas, é essencial conhecer os processos de retenção dessa molécula no solo. Neste trabalho, avaliou-se a lixiviação do fomesafen em quatro solos: Cambissolo, Latossolo Vermelho-Amarelo com pH corrigido e original, Argissolo Vermelho-Amarelo e Organossolo. Para isso, foram utilizados bioensaios, empregando-se o híbrido de sorgo BRS655 como planta indicadora da presença do fomesafen. Os solos foram acondicionados em colunas de PVC de 10 cm de diâmetro por 50 cm de comprimento, marcadas e seccionadas a cada 5 cm de distância. Aplicou-se o herbicida fomesafen no topo das colunas, na dose de 500 g ha-1 do fomesafen. Após 12 horas procedeu-se à simulação de chuva, com aplicação de uma lâmina de água de 80 mm. Realizaram-se avaliações de intoxicação das plantas e colheita da parte aérea, para determinação da matéria seca aos 21 dias após a semeadura do sorgo em cada coluna. A ordem decrescente de lixiviação foi: Cambissolo > Latossolo Vermelho-Amarelo, pH corrigido > Latossolo Vermelho-Amarelo, pH original > Argissolo Vermelho-Amarelo > Organossolo. Os fatores que mais afetaram a lixiviação, em ordem decrescente de importância, foram o teor de matéria orgânica, a textura e o pH do solo.

The use of pyroligneous acid (PA), a by-product of charcoal production, is an ancient practice applied in agriculture to control soil and plant pests and diseases. However, little is known about the chemical alterations that this product may cause on treated soil. Thus, the present work aimed to evaluate the effect of PA concentrations on soil ions movement and to verify possible soil chemical properties changes. Detachable columns were filled with Oxisol, submitted to application of 5 PA concentrations (0, 1, 2, 4, 8% v/v), followed by water infiltration in an amount corresponding to 1.5 times the soil total pore volume, and evaluated the soil of four depths (0-10, 10-20, 20-30, 30-40cm) and the leachate. The use of pyroligneous acid in concentrations up to 2 % (v/v) induces only slight decrease of k, Mg, basis saturation and total cation exchange capacity, in the 0-20 cm soil layer. The application of 4 % (v/v) and 8 % (v/v) pyroligneous acid induces severe increase on the potential acidity, and the decrease on the pH, basis saturation, total cation exchange capacity, and Ca concentration, in the layer of 0-20 cm soil. The P and K concentration reduces in the 0-20 cm soil layer by increasing from 1% to 8% the concentration of pyroligneous acid solution applied on soil surface. By increasing the PA concentration applied on the soil, there is increase of acidity, organic matter, P, K, Ca, and Mg, and decrease of sulfate in the leachate.

A disposição inadequada dos resíduos sólidos urbanos no solo compromete a qualidade do solo, da água e do ar e constitui fonte de compostos orgânicos, solventes e elementos traços. Neste trabalho foi estudado a sorção dos elementos Cd, Cu, Li, Pb e Zn nos solos das áreas de disposição de resíduos sólidos urbanos dos municípios de Campo Belo, Lavras e Pouso Alegre, MG com a finalidade de se verificar a vulnerabilidade da contaminação das águas subterrâneas. As isotermas de sorção apresentaram um bom ajuste ao modelo de Freundlich, permitindo a sua utilização na previsão de retenção destes elementos traços nos solos de áreas de disposição final de resíduos sólidos urbanos dos municípios em questão para as concentrações estudadas. O solo do município de Pouso Alegre foi o que apresentou a menor potencialidade de lixiviação dos elementos traços avaliados, sendo o solo de Lavras o de maior vulnerabilidade no que se refere ao potencial de contaminação das águas subterrâneas, exigindo um maior controle na disposição de resíduos sólidos contendo elementos traços facilmente solubilizados.

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The objective of this research was to evaluate the contaminant potential of the leachate from soils treated with increasing doses of biosolids. The experiment was carried out in protected cultivation in clayey (Eutrophic RED LATOSOL) and sandy texture (Dystrophic YELLOW RED LATOSOL) soils. The experimental design was completely randomized with five treatments, six repetitions and two soil types: T1 - absence of biosolids, T2-T6, respectively 0, 15, 30, 45 and 60 ton ha-1 of biosolids. The vessels (leaching column) were made by PVC tubes 0.50 m high and 0.10 m in diameter at its base is adapted a perforated PVC cap for collecting the leached material. Each column was filled with 3,141.6 cm3 soil (sandy or clayey), of which the amounts of biosolid. After this stage, the plots were taken to 70% of the field capacity incubated for 60 days and after that period the leachate was collected and evaluated as: pH, electrical conductivity and contents of K, Ca and Mg. The results indicated that increased doses of biosolids lead to elevated pH. It was concluded that the clay soil supported higher doses of biosolids in relation to the sandy soil, presenting leachates with lower pollutant potential. [ABSTRACT FROM AUTHOR]

Os herbicidas usados na cultura do arroz Clearfield® podem persistir no ambiente e causar danos no arroz não tolerante, cultivado em sucessão. Esse dano pode ser de intensidade variável, dependendo, dentre outros fatores, do movimento ascendente do herbicida para região de absorção do sistema radicular das plantas. O objetivo desta pesquisa foi verificar o efeito da altura do lençol freático no movimento ascendente do herbicida composto pela mistura formulada de imazethapyr e imazapic. Para isso, foram coletados lisímetros de solo com auxílio de tubos de PVC (15x30cm). O herbicida foi aplicado na superfície inferior dos lisímetros, onde foram simulados diferentes profundidades do lençol freático (0, 5, 10, 15 e 25cm da superfície do solo). Os lisímetros permaneceram nessa condição por período de 150 dias, quando foram cortados longitudinalmente, seccionados em porções de 5cm (0-5 a 25-30cm) e realizado bioensaio com a cultivar de arroz não tolerante, IRGA 417. Com os resultados obtidos, foi possível concluir que ocorre movimento ascendente da mistura formulada dos herbicidas imazethapyr e imazapic ao longo do perfil do solo de várzea durante o período da entressafra do arroz irrigado, sendo este maior quando o lençol freático está localizado mais próximo da superfície do solo. O movimento ascendente através da diluição do herbicida na solução do solo ocorre por fluxo de massa através do arraste pela água, transportada por capilaridade para zonas mais superficiais do solo.

O desbalanço entre Ca2+, Mg2+ e K+ no solo como consequência das aplicações elevadas de gesso deve-se às relações de tamanho (raio iônico) e densidades de cargas (relação carga/raio) de cada espécie iônica. Quanto maior a densidade de carga, mais intensa será a ligação iônica do cátion com íons de cargas opostas como OH- e SO4-2. Dessa maneira, o uso excessivo de gesso agrícola, sem considerar o balanço de cargas das partículas do solo; o equilíbrio iônico; e a CTC podem resultar em expressiva lixiviação ao longo do perfil do solo. O objetivo deste estudo foi avaliar o efeito de elevadas doses de gesso (0, 7 e 56 t ha-1) nos teores de Ca2+, Mg2+, K+ e pH na solução de um Latossolo Vermelho distrófico cultivado com cafeeiro, obtida pelo método adaptado do extrato aquoso. O solo foi amostrado nas profundidades de 0,15-0,25; 0,35-0,45; 0,75-0,85; 1,15-1,25 e 2,35-2,45 m na linha de plantio, em quatro tratamentos: G-0 - gesso no preparo (aplicação ocorreu em setembro de 2008, distribuído a lanço, na quantidade de 2 t ha-1) e sem gesso na linha de plantio; G-7 - gesso adicionado durante a preparação do solo (2 t ha-1), na mesma condição do G-0 e 7,0 t ha-1 de gesso na linha de plantio; G-56 - gesso adicionado durante a preparação do solo (2 t ha-1), na mesma condição do G-0 e 56 t ha-1 de gesso na linha de plantio (nessas parcelas experimentais as entrelinhas de plantio foram cobertas com braquiária); e CV-7: ausência de braquiária na entrelinha, com gesso no preparo e 7 t ha-1 de gesso na linha, com três repetições distribuídas em blocos ao acaso, totalizando 60 amostras. Após 16 meses da adição de gesso, observou-se redução do pH na solução do solo nas profundidades de 0,15-0,25; 0,35-0,45 e 0,75-0,85 m. A aplicação de gesso agrícola foi eficiente na melhoria do ambiente radicular no subsolo, aumentou a concentração de Mg2+ e Ca2+ na solução do solo, mas reduziu o K+ em profundidade, a partir de 0,85 m. Os teores de Ca2+ e Mg2+ trocáveis na solução do solo estiveram acima do nível crítico; entretanto, os teores de K+ trocável se mantiveram na faixa do valor crítico, indicado para o desenvolvimento da cultura.