Humic Haplustox under different land uses in a high altitude environment in the Agreste region of Pernambuco, Brazil

The Garanhuns Plateau in the Agreste region of the State of Pernambuco, Brazil is characterized by humid climatic conditions due to orographic rains, unlike the surrounding semiarid region. These soils are subjected to intense agricultural use and are extremely important for the regional economy. This study was carried out in the municipality of Brejão in the Agreste region with the aim of assessing changes in humic Haplustox soils subjected to different land uses. Four plots with different vegetation covers (native forest, secondary shrubby vegetation (capoeira), traditional cropping system, and planted pasture) were selected, and samples were taken from a soil profile and four small pits surrounding it at each site. Physical and chemical properties were assessed, including aggregate stability, humic organic fractions, and a microbiological evaluation through determination of basal respiration, microbial biomass carbon, and metabolic quotient. The soils under study showed physical and chemical properties typical of a Haplustox, such as low nutrient content, low cation exchange capacity, and high levels of acidity and Al saturation. The total organic carbon (TOC) contents were high regardless of the type of land use. Aggregates < 2 mm were dominant in all the conditions under study. The TOC content was higher in the soil under capoeira, 43.91 g kg-1 on the surface, while 34.36 and 33.43 g kg-1 of TOC were observed in the first layer of forest and pasture soils, respectively. While the microbial biomass C (MBC) was greater than 700 mg kg-1 in the forest and pasture areas (in the 0-5 cm layer), and 588 mg kg-1 in the soil under capoeira, these numbers were not statistically different. In the cultivated soil area, there was a reduction of around 28 % in TOC and MBC contents. Agricultural activity contributed to degradation of the humic horizon, as can be seen from a significant decrease in the TOC and changes in the relative distribution of the humic fractions. In contrast, aggregate stability was not altered as a function of the different land uses; the soil under planted pasture and capoeira were similar to the soil under native forest. Humin was the most important humified fraction for C reserves, contributing over 40 % of the TOC in these soils.

EFFECT OF RICE STRAW AND NITRATE LEVELS IN SOIL SOLUTION ON NITROUS OXIDE EMISSION

Among the greenhouse gases, nitrous oxide (N2O) is considered important, in view of a global warming potential 296 times greater than that of carbon dioxide (CO2) and its dynamics strongly depend on the availability of C and mineral N in the soil. The understanding of the factors that define emissions is essential to develop mitigation strategies. This study evaluated the dynamics of N2O emissions after the application of different rice straw amounts and nitrate levels in soil solution. Pots containing soil treated with sodium nitrate rates (0, 50 and 100 g kg-1 of NO−3-N) and rice straw levels (0, 5 and 10 Mg ha-1), i.e., nine treatments, were subjected to anaerobic conditions. The results showed that N2O emissions were increased by the addition of greater NO−3 amounts and reduced by large straw quantities applied to the soil. On the 1st day after flooding (DAF), significantly different N2O emissions were observed between the treatments with and without NO−3 addition, when straw had no significant influence on N2O levels. Emissions peaked on the 4th DAF in the treatments with highest NO−3-N addition. At this moment, straw application negatively affected N2O emissions, probably due to NO−3 immobilization. There were also alterations in other soil electrochemical characteristics, e.g., higher straw levels raised the Fe, Mn and dissolved C contents. These results indicate that a lowering of NO−3 concentration in the soil and the increase of straw incorporation can decrease N2O emissions.

Genetic parameters and estimated genetic gains in young rubber tree progenies

The objective of this work was to assess the genetic parameters and to estimate genetic gains in young rubber tree progenies. The experiments were carried out during three years, in a randomized block design, with six replicates and ten plants per plot, in three representative Hevea crop regions of the state of São Paulo, Brazil. Twenty-two progenies were evaluated, from three to five years old, for rubber yield and annual girth growth. Genetic gain was estimated with the multi-effect index (MEI). Selection by progenies means provided greater estimated genetic gain than selection based on individuals, since heritability values of progeny means were greater than the ones of individual heritability, for both evaluated variables, in all the assessment years. The selection of the three best progenies for rubber yield provided a selection gain of 1.28 g per plant. The genetic gains estimated with MEI using data from early assessments (from 3 to 5-year-old) were generally high for annual girth growth and rubber yield. The high genetic gains for annual girth growth in the first year of assessment indicate that progenies can be selected at the beginning of the breeding program. Population effective size was consistent with the three progenies selected, showing that they were not related and that the population genetic variability is ensured. Early selection with the genetic gains estimated by MEI can be made on rubber tree progenies.

Excitação eletrônica das moléculas de metacrilato de metila e estireno na região do ultravioleta de vácuo

Angle-resolved electron energy-loss spectra have been measured for the methyl methacrylate (MMA) and styrene molecules in the 0 - 50 eV energy range. The spectra have been obtained at 1 keV incident energy, with an energy resolution of 0.8 eV and covering an angular range of 2.0 to 7.0 degrees. Within our knowledge, this is the first gas-phase excitation spectrum for MMA and styrene in this energy range. The spectra of MMA at small scattering angles are dominated by an intense peak at 6.7 eV followed by a broad band centered at about 16 eV. In the case of styrene, six bands can be observed in the spectra. Based on the angular behaviour of the excitation spectra of these molecules, the low-lying peaks observed are considered to be associated predominantly with dipole-allowed processes. In both cases, new bands can be observed for excitation energies greater than 20 eV. This could be associated with dipole-forbidden transitions to shake-up and doubly-excited states.

Método de estudo da adsorção de triadimenol com micro-colunas de solo e centrifugação

Normally, the determination of equilibrium constants (k d) in batch experiments uses a high solution to soil ratio, which does not represent field conditions. In this study we present an alternative method to evaluate adsorption constants, using micro-columns of soil at higher soil to solution ratios. The centrifugation force and equilibration time were investigated. The triadimenol distribution along the column profile is controlled by diffusion and equilibration times greater than 24 h are needed to achieve reproducibility. The centrifugation force must be superior to 670 g in order to guarantee enough extraction of the liquid solution from the soil columns.

Análise de praguicidas organofosforados em água por extração em fase sólida (SPE) utilizando discos C18 e cromatografia em fase gasosa: avaliação da contaminação do reservatório de Furnas (MG-Brasil)

Solid phase extraction (SPE) in C18 disks has been optimized and validated for extraction of 5 organophosphorus (OP) pesticides in water. Extraction has been followed by separation and detection by gas chromatography/flame photometry. Excellent linearity was obtained for all compounds (r greater than 0.99), with CVs between 1.0-6.9%, recoveries between 73-95% and quantification limits between 2.5-5.0 µg L-1. Samples from Furnas dam were analyzed monthly during one year and 10% showed OP pesticide residues.

Solid phase extraction of iron and lead in environmental matrices on amberlite xad-1180/pv

A solid phase extraction procedure using Amberlite XAD-1180/Pyrocatechol violet (PV) chelating resin for the determination of iron and lead ions in various environmental samples was established. The procedure is based on the sorption of lead(II) and iron(III) ions onto the resin at pH 9, followed by elution with 1 mol/L HNO3 and determination by flame atomic absorption spectrometry. The influence of alkaline, earth alkaline and some transition metals, as interferents, are discussed. The recoveries for the spiked analytes were greater than 95%. The detection limits for lead and iron by FAAS were 0.37 µg/L and 0.20 µg/L, respectively. Validation of the method described here was performed by using three certified reference materials (SRM 1515 Apple Leaves, SRM 2711 Montana Soil and NRCC-SLRS-4 Riverine Water). The procedure was successfully applied to natural waters and human hair.

Outdoor/indoor air quality in primary schools in Lisbon: a preliminary study

Simultaneous measurements of outdoor and indoor pollution were performed at three schools in Lisbon. Volatile organic compounds (VOCs), formaldehyde and NO2 were passively monitored over a two-week period. Bacterial and fungal colony-forming units and comfort parameters were also monitored at classrooms and playgrounds. The highest indoor levels of CO2 (2666 μg/m³), NO2 (40.3 μg/m³), VOCs (10.3 μg/m³), formaldehyde (1.03 μg/m³) and bioaerosols (1634 CFU/m³), and some indoor/outdoor ratios greater than unity, suggest that indoor sources and building conditions might have negative effects on air indoors. Increasing ventilation rates and use of low-emission materials would contribute towards improving indoor air quality.

Fracionamento de cobre em proteínas do plasma, músculo e fígado de tilápia do Nilo

Copper fractionation in plasma, muscle and liver of Nile tilapia was performed after protein separation by 2D-PAGE. SR XRF analysis indicated the presence of copper in three protein spots of plasma, and in two protein spots of muscle and liver, respectively. Copper ions were found to be distributed mostly in proteins that had a molar mass of less than 54 kDa and greater than 13 kDa and a pI in the 5.3-9.3 range. The copper concentration bound to these proteins was determined by GFAAS which showed concentrations in the 1.20-4.82 mg g-1 range.

Análise de agrotóxicos em água usando extração líquido-líquido com partição em baixa temperatura por cromatografia líquida de alta eficiência

This study optimized and validated the liquid-liquid extraction technique with partition at low temperature (LLE-PLT) for identification and quantification of four pesticides (chlorpyrifos, λ-cyhalothrin, permethrin, bifenthrin) in water samples. Analyses were performed by HPLC-UV. The technique was efficient for pesticide recovery with extraction exceeding 86%. Chromatographic response was linear for the four compounds in the 10-45 µg L-1 range, with correlation coefficients greater than 0.99. Limits of detection and quantitation were less than 3.5 µg L-1 and equal to 10 µg L-1, respectively. The proposed method was applied to 29 water samples from the Jaíba Project in northern Minas Gerais.

Estudo do comportamento da lipase comercial Lipozyme RM IM em reações de esterificação para obtenção de biodiesel

The aim of this work was to study monoalkyl ester synthesis catalyzed by immobilized lipase Lipozyme RM IM via the esterification reaction. Yields of over 90% were obtained with butanol in esterification reactions with oleic acid. In the reactions with deodorizer distillates of vegetable oils and butanol, the conversion obtained was greater than 80% after 2.5 h. For the esterification reaction of palm fatty acid deodorizer distillate (PFAD) and butanol, seven reuse cycles of Lipozyme RM IM were carried out and the final conversion was 42% lower than the initial conversion.

Otimização e validação da extração sólido-líquido e purificação em baixa temperatura de HPAs em lodo de esgoto

In this study, a method of solid-liquid extraction and purification at low temperature (SLE-PLT) to determine 16 polycyclic aromatic hydrocarbons (PAHs) in sewage sludge was optimized and validated. The analyses were performed by HPLC-UV. The extraction phase, homogenization procedure, influence of pH, ionic strength and clean-up of the extracts were optimized. Recoveries were higher than 63.4% for 11 PAHs. The correlation coefficients were greater than 0.99 and limits of detection and quantitation were less than 0.060 and 0.15 µg g-1, respectively. These values were lower than the maximum residue limits of PAHs established by European legislation. SLE-PLT proved a more practical, economical method with fewer steps compared to Soxhlet extraction (reference method) for PAHs in sewage sludge.

DETERMINAÇÃO ESPECTROFOTOMÉTRICA DE METILDOPA EM ENSAIO DE DISSOLUÇÃO DE COMPRIMIDOS UTILIZANDO EXTRATO DE RABANETE COMO FONTE DE PEROXIDASE

An enzymatic spectrophotometric method for the determination of methyldopa in a dissolution test of tablets was developed using peroxidase from radish (Raphanus sativus). The enzyme was extracted from radish roots using a phosphate buffer of pH 6.5 and partially purified through centrifugation. The supernatant was used as a source of peroxidase. The methyldopachrome resulting from the oxidation of methyldopa catalyzed by peroxidase was monitored at 480 nm. The enzymatic activity was stable for a period of at least 25 days when the extract was stored at 4 or -20 ºC. The method was validated according to RDC 899 and ICH guidelines. The calibration graph was linear in the range 200-800 µg mL-1, with a correlation coefficient of 0.9992. The limits of detection and quantification in the dissolution medium were 36 and 120 µg mL-1, respectively. Recovery was greater than 98.9%. This method can be applied for the determination of methyldopa in dissolution tests of tablets without interference from the excipients.

Survival of Botrytis cinerea as mycelium in rose crop debris and as sclerotia in soil

Botrytis blight caused by Botrytis cinerea is an important disease of rose (Rosa hybrida) grown in greenhouses in Brazil. As little is known regarding the disease epidemiology under greenhouse conditions, pathogen survival in crop debris and as sclerotia was evaluated. Polyethylene bags with petals, leaves, or stem sections artificially infected with B. cinerea were mixed with crop debris in rose beds, in a commercial plastic greenhouse. High percentage of plant parts with sporulation was detected until 60 days, then sporulation decreased on petals after 120 days, and sharply decreased on stems or leaves after 90 days. Sporulation on petals continued for 360 days, but was not observed on stems after 150 days or leaves after 240 days. Although the fungus survived longer on petals, stems and leaves are also important inoculum sources because high amounts of both are deposited on beds during cultivation. Survival of sclerotia produced on PDA was also quantified. Sclerotia germination was greater than 75% in the initial 210 days and 50% until 360 days. Sclerotia weight gradually declined but they remained viable for 360 days. Sclerotia were produced on the buried petals, mainly after 90 days of burial, but not on leaves or stems. Germination of these sclerotia gradually decreased after 120 days, but lasted until 360 days. Higher weight loss and lower viability were observed on sclerotia produced on petals than on sclerotia produced in vitro

Virulence and rep-PCR analysis of Pyricularia grisea isolates from two Brazilian upland rice cultivars

The phenotypic and genetic diversity of 77 isolates of Pyricularia grisea collected from two upland rice cultivars, Maravilha and Primavera, was studied. Isolates exhibiting compatible reaction to cv.Primavera were incompatible to cv.Maravilha and vice versa, with the exception of six isolates that were compatible to both cultivars. The virulence of isolates from cv. Maravilha on 32 test genotypes of rice was significantly higher (t = 9.09, p < 0.0001) than the isolates from cv.Primavera. A phenogram constructed from virulence data showed two main groups, one constituted mainly of isolates from cv.Primavera (97.6%) and the other of isolates from cv.Maravilha (91.17%). Rep-PCR analysis of isolates using two primers designed from sequences of Pot2 showed that isolates could be clustered broadly into two groups. The average similarity within a cluster of isolates from cv.Primavera was significantly greater than the average similarity among the isolates of cv.Maravilha (t = 5.37, p < 0.0001). There was close correspondence between clusters based on PCR and virulence data (r = 0.48, p < 0.011). The results showed that isolates of P. grisea were cultivar specific and had low phenotypic and genetic diversity.