Time filter

Source Type

Toledo, Brazil

Goncalves Jr. A.C.,West Parana State University | Rubio F.,West Parana State University | Meneghel A.P.,West Parana State University | Coelho G.F.,West Parana State University | And 2 more authors.
Revista Brasileira de Engenharia Agricola e Ambiental

This study aimed to evaluate the efficacy of crambe seeds (Crambe abyssinica Hochst) as adsorbent material in the removal of the toxic metals cadmium, lead and chromium from contaminated solutions. The byproduct was obtained from oil extraction of crambe seeds in a Soxhlet system. In kinetic tests, the adsorbent masses had varied in solutions containing the metals under pH 5.0 and 7.0. Metal concentrations were determined by flame atomic absorption spectrometry (FAAS). According to optimal conditions found, the adsorption assays were performed for obtaining the isotherms of each metal, which were linearized in agreement with the mathematical models of Langmuir and Freundlich. According to the obtained results, the adsorbent was effective in removing the assessed metals in aqueous solutions, being feasible its employment as an alternative material for the adsorption of metals, besides being a byproduct, which has undergone no prior treatment. Source

Goncalves Jr. A.C.,West Parana State University | Meneghel A.P.,West Parana State University | Rubio F.,West Parana State University | Strey L.,West Parana State University | And 2 more authors.
Revista Brasileira de Engenharia Agricola e Ambiental

This study evaluated the efficacy of moringa seeds (Moringa oleifera Lam.) as an adsorbent material for removing toxic heavy metals such as cadmium, lead, and chromium from contaminated solutions. The effect of the adsorbent mass was investigated at two pH conditions (5.0 and 7.0). The optimized conditions were 0.300 g of adsorbent at pH 5.0, used for the isotherms construction, and linearized according to Langmuir and Freundlich models. Results showed that cadmium adsorption was similar in both the models used. For lead, the Freundlich model had the best adjustment and chromium was better adjusted by the Langmuir model. It was concluded that the adsorbent was effective in the remediation of solutions containing cadmium, lead and chromium, thus, its use as sustainable alternative material is feasible, since it has low cost, does not need a previous treatment and it is a byproduct. Source

Legumes need large amounts of N to grow satisfactorily. Under low NO3 - availability in the soil, many legumes meet their N requirements by N2 fixation in association with rhizobia. Both NO3 - uptake and N2 fixation decrease as temperature exceeds optimal growth conditions, but the mechanisms of regulation of N2 fixation and NO3 -/NH4 + assimilation under high temperature stress are not completely understood. We describe an experiment in which physiological mechanisms regulating N metabolism of common bean (Phaseolus vulgaris L.) are investigated in plants submitted to daily maximum temperatures of 28, 34 and 39°C. Common bean was grown in symbiosis with each of six rhizobial strains-belonging to four different species and varying in N2 fixation effectiveness-or fertilized with NO3 - until flowering. Harvest measurements included the activities of shoot, stem and root NO3 - reductase (NR), nodule glutamine synthetase (GS), NADH-dependent glutamate synthase (GOGAT), nitrogenase, phosphoenol pyruvate carboxylase (PEPcase), N-export rates by nodules and concentration of N compounds in the xylem sap. Higher temperatures inhibited N2 fixation resulting in lower proportion of ureide-N in nodules and xylem sap of nodulated plants in relation to amide-N and α-amino-N. Higher temperatures consistently reduced the activity of NR in leaves of N-fertilized plants. Higher temperatures also decreased N exported from nodules and activities of nitrogenase, GS, GOGAT and PEPcase. The rate of decreases varied in plants with different strains. Furthermore, the activities of GS and GOGAT were more strongly affected by high temperatures than the activity of nitrogenase. There was a remarkable increase in the concentration of NH4 +-N and ureide-N in the nodules when GS and GOGAT activities decreased. Therefore, the results provide evidence that N2 fixation in common bean submitted to heat stress is limited by NH4 + assimilation via GS-GOGAT rather than by decreased activity of nitrogenase. Rhizobial effectiveness determined the degree of down-regulation of GS-GOGAT activity in nodule tissues. © 2013 Elsevier B.V. Source

Castelli M.,Paranaense University | Urcoviche R.C.,Paranaense University | Gimenes R.M.T.,Unipar | Alberton O.,Paranaense University
Journal of Food, Agriculture and Environment

Maize (Zea mays L.) is commercially very important and needs sustainable production systems. The no-till system (NT) offers several advantages in relation to the conventional tillage system (CT), reducing soil losses by erosion and increasing the soil organic matter. Moreover, different soil managements might affect arbuscular mycorrhizal fungi (AMF) community, which may change plant capacity to uptake of nutrients and water. The objective of this study was to evaluate the influence of soil management under nine-year NT and CT with or without fungicide application on seeds, and its effects on AMF community and maize productivity. The experiment was carried out in a field with eutrophic red Argisol (PVe - Ultisol) type and had random block with split-plots arrangement, with six replications. We evaluated density and diversity of AMF spores, AMF root colonization, maize dry mass and grain yield. The spore density and AMF root colonization were higher under NT without fungicide addition to the seeds. The most frequently found AMF genera were Glomus spp., Gigaspora spp. and Acaulospora spp. The NT increased Acaulospora spp., whereas CT increased Glomus spp. Plant dry mass and grain yield were higher under NT and this effect was more visible without fungicide addition to seeds. This corroborates the increase of AMF root colonization under NT without fungicide. It is concluded that NT without fungicide addition to maize seeds was the best cropping management, increasing AMF root colonization and maize productivity, and was the most appropriate and sustainable management of maize production. Source

Handling load is an activity that predisposes the worker to risks due to biomechanical factors, excess of force, inadequate positions and organizational factors. These organizational factors may reflect injuries to workers' health and production when used in an inadequate way. This study was carried out using 3 wholesale businesses, aiming to identify the risk factors that could lead to the prevalence of muscle-skeletal symptoms. An organizational questionnaire, a Nordic questionnaire for musculoskeletal symptoms and a guide for assessment and prevention of risks related to handling load was applied to a select sample of 134 workers. It was possible to notice that the loading, the adopted positions and the pain symptoms (63.4% of the sample), associated to the previous factors, may represent a health risk. The results supported the studies, establishing strong indications between physical load of work and muscle-skeletal symptoms. Source

Discover hidden collaborations