Hydraulic conductivity and soil-sewage sludge interactions

One of the main problems faced by humanity is pollution caused by residues resulting from the production and use of goods, e.g, sewage sludge. Among the various alternatives for its disposal, the agricultural use seems promising. The purpose of this study was to evaluate the hydraulic conductivity and interaction of soil with sandy-silty texture, classified as Spodosols, from the Experimental Station Itapirema - IPA, in Goiana, state of Pernambuco, in mixtures with sewage sludge from the Mangueira Sewage Treatment Station, in the city of Recife, Pernambuco at rates of 25, 50 and 75 Mg ha-1. Tests were conducted to let water percolate the natural saturated soil and soil-sludge mixtures to characterize their physical, chemical, and microstructural properties as well as hydraulic conductivity. Statistical data analysis showed that the presence of sewage sludge in soils leads to an increase of the < 0.005 mm fraction, reduction in real specific weight and variation in optimum moisture content from 11.60 to 12.90 % and apparent specific dry weight from 17.10 and 17.50 kN m-3. In the sludge-soil mixture, the quartz grains were covered by sludge and filling of the empty soil macropores between grains. There were changes in the chemical characteristics of soil and effluent due to sewage sludge addition and a small decrease in hydraulic conductivity. The results indicate the possibility that soil acidity influenced the concentrations of the elements found in the leachate, showing higher levels at higher sludge doses. It can be concluded that the leaching degree of potentially toxic elements from the sewage sludge treatments does not harm the environment.

Body lipid deposition in Nile tilapia fed on rations containing tannin

The aim of this work was to evaluate the effect of tannin sources and levels in rations, on the productive performance and body lipid deposition of Nile tilapias (Oreochromis niloticus) during the finishing phase. Three hundred and forty-two fishes were distributed in 18 tanks. Rations were prepared using corn, sorghum varieties, with low and high tannin content, and tannic acid at 0.08, 0.34, and 0.60%. Weight gain, apparent feed conversion and protein efficiency rate were not influenced by the treatments. The highest body lipid deposition was observed for the tannic acid treatment (14.39%), while the diet containing sorghum with high tannin content yielded leaner body (12.01%) than that of sorghum with low tannin content (13.31%). Diets containing sorghum provided lower levels of visceral fat. Rations with tannin contents did not harm the productive performance of Nile tilapia.

Trichogramma pretiosum attraction due to the Elasmopalpus lignosellus damage in maize

The objective of this work was to evaluate if corn plants damaged by the lesser cornstalk borer (Elasmopalpus lignosellus) larvae release volatile organic compounds capable of attracting the egg parasitoid Trichogramma pretiosum. The treatments consisted of plants subjected to harm caused by E. lignosellus larvae, plants subjected to mechanical damage, and undamaged plants. The parasitoid was more attracted by the volatiles released by the insect damaged plants than to those released by undamaged corn plants, after 24 and 72 hours. The volatiles (Z)-3-hexenyl acetate, β-pinene, β-myrcene, (E)-4,8-dimethylnona-1,3,7-triene, and benzothiazole were released in significantly larger quantities by damaged plants. Volatiles released by corn plants damaged by E. lignosellus larvae may act as an indirect defense, attracting by T. pretiosum.

Mecanismo de fotodegradação de compostos orgânicos catalisada por TiO2

Conventional technology used in the treatment of wastewater has been pointed as a major environmental problem for sustainable development, since minimization is not addressed accordingly. Advanced oxidation processes (AOP), based on the formation of hydroxyl radical (•OH), a powerful oxidant agent, have been considered to be a potential technology for the destruction of many toxic compounds. Photocatalysis using solar light, an AOP, has been studied for nearly 20 years and recently attracted great interest as a clean-up technology. However, solar detoxification processes have not yet achieved commercial success. This article presents an overview of reaction mechanisms at the surface of semiconductors used as photocatalysts (specially TiO2), when heterogeneous photocatalysis is used to remove hazardous compounds from contaminated sites.

Gerenciamento de resíduos químicos em laboratórios de ensino e pesquisa

The generation of chemical residues in both teaching and research laboratories is a serious problem in Brazil. In this article, a Chemical Residues Management Program is presented and discussed. The Program is centered in different hierarchic positions, but driven by minimization. A common ground for discussion and distribution of related information is also proposed as a mean to spread the program throughout Brazilian Universities.

Uma abordagem robusta de cálculo aplicada a um sistema potenciométrico de medida de concentrações hidrogeniônicas em soluções aquosas

The data analyzed in this work were generated following the methodology developed by Molina et al.(J. Electroanal. Chem., 1979) for the calibration of a potentiometric system of measurement of hydrogen-ion concentrations resulting from neutralizations, at 25 ºC, of acidic or alkaline solutions at constant ionic strength (0.1 mol.l-1) held with NaClO4. The observed data present a serious deviation in relation to the mathematical model derived from the Nernst equation, for pH values ranging from 3 to 11, where pH=-log[H+]. We show that the minimization of the sum of the absolute values of the residuals gives estimates that are not influenced by outlying values.

Deposição eletrolítica catódica e anódica simultâneas para minimizar interferências de cobre e chumbo na determinação espectrofotométrica de cádmio em água e alimentos via reação com Verde de Malaquita e iodeto

Simultaneous electrolytic deposition is proposed for minimization of Cu2+ and Pb2+ interferences on automated determination of Cd2+ by the Malachite Green-iodide reaction. During electrolysis of sample in a cell with two Pt electrodes and a medium adjusted to 5% (v/v) HNO3 + 0.1% (v/v) H2SO4 + 0.5 mol L-1 NaCl, Cu2+ is deposited as Cu on the cathode, Pb2+ is deposited as PbO2 on the anode while Cd2+ is kept in solution. With 60 s electrolysis time and 0.25 A current, Pb2+ and Cu2+ levels up to 50 and 250 mg L-1 respectively, can be tolerated without interference. With on-line extraction of Cd2+ in anionic resin minicolumn, calibration graph in the 5.00 - 50.0 µg Cd L-1 range is obtained, corresponding to twenty measurements per hour, 0.7 mg Malachite Green and 500 mg KI and 5 mL sample consumed per determination. Results of the determination of Cd in certified reference materials, vegetables and tap water were in agreement with certified values and with those obtained by GFAAS at 95% confidence level. The detection limit is 0.23 µg Cd L-1 and the RSD for typical samples containing 13.0 µg Cd L-1 was 3.85 % (n= 12).

Gerenciamento de resíduos químicos e águas servidas no laboratório de isótopos estáveis do CENA/USP

A system for disposal and recovery of the main effluents and chemical waist from isotope separation plants and enriched compounds-15N and 34S production has been carried out at the Stable Isotope Laboratory (LIE) of the CENA/USP. Around four hundred thousand liters of effluents has been recovered yearly. Among the recovered chemical wastes, the more relevant are: ammonia; brome; ammonium and sodium sulfate; sodium hydroxide; sulfur dioxide; and hydrochloric acid. Chemical wastes containg recoverable heavy metals (Ag, Cr and Cu) and solvents (methanol, ethanol and acetone) are processed and recovered. Gaseous emissions, mainly H2S are used for recovery of heavy metals solutions. The minimization of the residues waters, as well the reduction of electric energy consume was established using a water deionization system. A cost/effect balance of the process is reported.

Caracterização físico-química de queijo prato por espectroscopia no infravermelho e regressão de mínimos quadrados parciais

In this work an analytical methodology for the determination of relevant physicochemical parameters of prato cheese is reported, using infrared spectroscopy (DRIFT) and partial least squares regression (PLS). Several multivariate models were developed, using different spectral regions and preprocessing routines. In general, good precision and accuracy was observed for all studied parameters (fat, protein, moisture, total solids, ashes and pH) with standard deviations comparable with those provided by the conventional methodologies. The implantation of this multivariate routine involves significant analytical advantages, including reduction of cost and time of analysis, minimization of human errors, and elimination of chemical residues.

Avaliação da contaminação de metais em sedimentos superficiais das praias do lago de Itaipu

This work was performed to evaluate the distribution of metals Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn in the sediment surface in the Itaipu Lake-PR-Brazil. It was also performed to measurement the pH, phosphorus, organic carbon and particle size. In accordance of international criteria of quality of sediment, the results indicate an anthropogenic collaborations since some metals reached an excessive values. The factor of contamination was also used to evaluate the levels of contamination. The levels of Cu and Pb indicate a moderate contamination, so that it's possible to do harm to the balance of the ecosystem studied.

Aumento da resposta analítica por meio da otimização do sistema de injeção sem divisão de fluxo em cromatografia gasosa empregando a lei dos gases ideais

This paper reports the development of an easy, fast and effective procedure for the verification of the ideal gas law in splitless injection systems in order to improve the response. Results of a group of pesticides were used to demonstrate the suitability of the approach. The procedure helps establish experimental parameters through theoretical aspects. The improved instrumental response allowed extraction with lower sample volumes, the minimization of time and costs and the simplification of sample preparation.

Principais técnicas de preparo de amostra para a determinação de resíduos de agrotóxicos em água por cromatografia líquida com detecção por arranjo de diodos e por espectrometria de massas

The determination of pesticide residues in water samples by Liquid Chromatography require sample preparation for extraction and enrichment of the analytes with the minimization of interferences to achieve adequate detection limits. The Solid Phase Extraction (SPE), Solid Phase Microextraction (SPME), Stir Bar Sorptive Extraction (SBSE) and Dispersive Liquid-Liquid Microextraction (DLLME) techniques have been widely used for extraction of pesticides in water. In this review, the principles of these sample preparation techniques associated with the analysis by Liquid Chromatography with Diode Array Detection (LC-DAD) or Mass Spectrometry (LC-MS) are described and an overview of several applications were presented and discussed.

Un método para enseñar el porqué suceden las reacciones químicas

A methodology is proposed for explaining one of the central questions in the teaching of general chemistry courses to freshman students: why do chemical transformations occur? The answer to this question is based on thermodynamics but we propose arriving at an answer in a more intuitive way by using computational tools in a bid to increase the motivation of students for learning chemistry.

Determinação de resíduos de agrotóxicos em leite bovino empregando método QuEChERS modificado e GC-MS/MS

Considering the possibility that pesticides used in cattle raising produce residues in milk and cause harm to public health, this study developed a multiresidue method for determination of pesticide residues in bovine milk, using a modified QuEChERS method for sample preparation, and quantification by GC-MS/MS. The method proved to be efficient, resulting in satisfactory recoveries in the range 71.1 to 117.4%, for 45 of the 48 compounds analyzed with RSD values < 17.3%. The method LOD and LOQ were3.0 and 10.0 µg L-1, respectively, except for cyfluthrin which showed 7.5 and 25.0 µg L-1.

Computational modeling for irrigated agriculture planning. Part II: risk analysis

Techniques of evaluation of risks coming from inherent uncertainties to the agricultural activity should accompany planning studies. The risk analysis should be carried out by risk simulation using techniques as the Monte Carlo method. This study was carried out to develop a computer program so-called P-RISCO for the application of risky simulations on linear programming models, to apply to a case study, as well to test the results comparatively to the @RISK program. In the risk analysis it was observed that the average of the output variable total net present value, U, was considerably lower than the maximum U value obtained from the linear programming model. It was also verified that the enterprise will be front to expressive risk of shortage of water in the month of April, what doesn't happen for the cropping pattern obtained by the minimization of the irrigation requirement in the months of April in the four years. The scenario analysis indicated that the sale price of the passion fruit crop exercises expressive influence on the financial performance of the enterprise. In the comparative analysis it was verified the equivalence of P-RISCO and @RISK programs in the execution of the risk simulation for the considered scenario.