372 resultados para remoção de nutrientes


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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Pós-graduação em Agronomia (Produção Vegetal) - FCAV

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Microbiologia Agropecuária - FCAV

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Pós-graduação em Agronomia (Horticultura) - FCA

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Pós-graduação em Aquicultura - FCAV

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Particularmente de gases industriais, biogás e demais condições que exijam a purificação de gases antes de sua emissão para a atmosfera, visando a remoção de H~ 2~S, através da reação de oxidação deste gás com uma solução de íons Fe^ 3+^ produzidos por células imobilizadas de Acidithiobacillus ferrooxidans, uma bactéria quimioautotrófica e acidofílica, oxidante de ferro e formas reduzidas de enxofre. Como resultado do processo de oxidação do H~ 2~S pelos íons Fe^ 3+^ ocorre a produção de enxofre elementar (elemento recuperável no processo) e de íons Fe^ 2+^, os quais são re-oxidados pela bactéria à íons Fe^ 3+^ . Este reagente retorna então ao sistema para um novo ciclo de oxidação do H~ 2~S.

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The aim of this study was to verify the kinetics of lactate production and removal in slalom kayak athletes, K1 category, during official competition. Eight male athletes (22,6 ± 4,3 years) participated of the study. For the analysis of lactate, 25µL of capillary blood were collected. The kinetics of lactate removal was performed before the warm-up (Pre), just after the competitors exit from the river (Post 0'), 5 (Post 5'), and 20 (Post 20') minutes. The results demonstrated a significant increase in lactate concentrations (9.8 mmol/l, 9.4 mmol/l and 6.6 mmol/l) at 0', 5' and 20' post respectively, with values of P<0.01. The findings indicate that after 20 minutes the values of lactate reduced significantly (P<0.05) compared to Pre exercise, suggesting that the athletes would indicate good metabolic conditions for the second turn of the race.

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The effects on soil chemical properties brought about by cover crops vary considerably. This study was conducted to evaluate nutrient uptake by five cover crops used for grain, seed and forage production at different seed densities per hectare, as well as uptake by spontaneous vegetation, and their effect on the chemical properties of two Oxisols when grown in rotation with soybean and corn. The experiments were set up in Votuporanga, SP, Brazil and Selvíria, MS, Brazil in March 2008 after conventional soil tillage. A randomized complete block experimental design was used with four replications with the following cover crops at different seed densities: Sorghum bicolor at 6, 7 and 8 kg ha-1; Pennisetum americanum at 10, 15 and 20 kg ha-1; Sorghum sudanense at 12, 15 and 18 kg ha-1; hybrid of Sorghum bicolor with Sorghum sudanense at 8, 9 and 10 kg ha-1; and Urochloa ruziziensis at 8, 12 and 16 kg ha-1. We also used a spontaneous vegetation control. After management of the cover crops, in the first year of study, soybean was sown in no-tillage system and, in the second year, corn was sown, also in a no-tillage system. We evaluated the dry matter yield of different cover crops, nutrient uptake by the cover crops, and the chemical changes in the soil. It was found that in clayey soils with high aluminum content, as in Selvíria, sudan grass at a seed density of 18 kg ha-1, and sorghum at a seed density of 6 kg ha-1, in combination with liming, contributed to reduction of aluminum content and high potential acidity and an increase in base saturation. The different seed densities of each cover crop did not affect the dry matter yield of the cover crop itself, but affected nitrogen uptake of the hybrid Sorghum bicolor with Sorghum sudanense at a seed density of 10 kg ha-1, with lower uptake than at a seed density of 8 kg ha-1. Seed density also affected the organic matter content in the soil with sudan grass, with the seed density of 15 kg ha-1 providing more organic matter content than a seed density of 18 kg ha-1.

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The objective of this study was to evaluate the growth, the morphological alterations and the mineral composition of brazilwood (Caesalpinia echinata) plants caused by mineral nutrients omission in a green house experiment. The experimental units were distributed in the green house according to a completely random design. The treatments, each repeated five times, were the following : check (natural soil), complete (N, P, K, Ca, Mg, S, B, Cu, Mn, and Zn) and a complete solution but for the omission of one of the nutrients in parenthesis. Each plot was represented by a plant growing in a 7 dm3 vase filled with Quartzarenic Neosol. The analyzed variables were the following: visual nutritional deficiency symptoms, plant height, stem diameter, shoot dry matter, stem, branches and leaves included, and leaf nutrients level. The omission of nitrogen limited plant growth in height and shoot biomass production. The first visual deficiency symptoms were those due to N omission followed by those caused by P, Ca, Mg, S, Cu, and Mn omissions. Later on the K and B deficiency symptoms became visible. The omission of a nutrient always caused its level in the leaves to be significantly lower than that found when it was not omitted.

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The objective of this work was to determine nutrient deposition on the carcass of bullfrog (Lithobates catesbeianus) tadpoles using a nonlinear model. A total of 2,700 tadpoles with an average weight of 0.039 g were used. Commercial ground feed containing 55% crude protein was offered ad libitum. The animals were weighed and evaluated every ten days for analysis of crude protein, ether extract, water, and mineral salt contents. The parameters of the Gompertz model were estimated by the modified Gauss-Newton method, and the deposition rates (g per day) over time were calculated by the resulting equation. The values found for the parameters of the Gompertz equation, used to describe nutrient deposition on tadpole carcass, showed biological interpretation. Maximum deposition rate (t*) was observed on the 36.2331th day for protein, on the 37.1420th day for water, on the 35.2971th day for mineral salt, and on the 41.3547th day for fat. Nutrient intake from the diet is higher than the deposition rate on the tadpole carcass.