Avaliação de características de ácidos húmicos de resíduos de origem urbana: I. métodos espectroscópicos (UV-Vis, IV, RMN 13C-CP/MAS) e microscopia eletrônica de varredura

Foram caracterizados fisico-quimicamente ácidos húmicos, obtidos de composto de resíduos sólidos urbanos (AH-CRSU) e de lodo de estação de tratamento de esgoto (AH-LETE), ambos produzidos na cidade do Rio de Janeiro, por meio da análise da composição elementar, acidez total, de dados espectroscópicos (UV-Vis; IV, RMN de 13C-CP/MAS) e microscopia eletrônica de varredura (MEV). A análise das características estruturais revelou diferenças entre os AHs estudados. A presença de sistemas aromáticos foi observada por meio da espectroscopia de UV-Vis, indicando sistemas mais substituídos nos AH-LETE. A espectroscopia na região do infravermelho (IV) mostrou a presença de estruturas alifáticas nos AHs e maior complexidade nos sinais de absorção devida a polissacarídeos nos AH-CRSU. Além disso, foram observados grupos OH, COOH, COO-, CO2NH2, e confirmada a presença de sistemas aromáticos. Com a análise de RMN de 13C-CP/MAS, foi possível verificar as diferenças quantitativas nos diferentes tipos de carbono. Os AH-LETE apresentaram maior quantidade de grupos aromáticos e de COOH. A análise de RMN de 13C-CP/MAS também mostrou presença de polissacarídeos, N em aminoácidos e grupamentos OCH3. O conjunto de propriedades avaliadas permitiu indicar que a fração ácidos húmicos dos resíduos é "do tipo" ou "análoga" aos ácidos húmicos de origem pedogênica.

Molecular analysis of the bacterial diversity in a specialized consortium for diesel oil degradation

Diesel oil is a compound derived from petroleum, consisting primarily of hydrocarbons. Poor conditions in transportation and storage of this product can contribute significantly to accidental spills causing serious ecological problems in soil and water and affecting the diversity of the microbial environment. The cloning and sequencing of the 16S rRNA gene is one of the molecular techniques that allows estimation and comparison of the microbial diversity in different environmental samples. The aim of this work was to estimate the diversity of microorganisms from the Bacteria domain in a consortium specialized in diesel oil degradation through partial sequencing of the 16S rRNA gene. After the extraction of DNA metagenomics, the material was amplified by PCR reaction using specific oligonucleotide primers for the 16S rRNA gene. The PCR products were cloned into a pGEM-T-Easy vector (Promega), and Escherichia coli was used as the host cell for recombinant DNAs. The partial clone sequencing was obtained using universal oligonucleotide primers from the vector. The genetic library obtained generated 431 clones. All the sequenced clones presented similarity to phylum Proteobacteria, with Gammaproteobacteria the most present group (49.8 % of the clones), followed by Alphaproteobacteira (44.8 %) and Betaproteobacteria (5.4 %). The Pseudomonas genus was the most abundant in the metagenomic library, followed by the Parvibaculum and the Sphingobium genus, respectively. After partial sequencing of the 16S rRNA, the diversity of the bacterial consortium was estimated using DOTUR software. When comparing these sequences to the database from the National Center for Biotechnology Information (NCBI), a strong correlation was found between the data generated by the software used and the data deposited in NCBI.

Structural changes and degradation of Red Latosols under different management systems for 20 years

Soils are the foundation of terrestrial ecosystems and their role in food production is fundamental, although physical degradation has been observed in recent years, caused by different cultural practices that modify structures and consequently the functioning of soils. The objective of this study was to evaluate possible structural changes and degradation in an Oxisol under different managements for 20 years: no-tillage cultivation with and without crop rotation, perennial crop and conventional tillage, plus a forested area (reference). Initially, the crop profile was described and subsequently, 10 samples per management system and forest soil were collected to quantify soil organic matter, flocculation degree, bulk density, and macroporosity. The results indicated structural changes down to a soil depth of 50 cm, with predominance of structural units ∆μ (intermediate compaction level) under perennial crop and no-tillage crop rotation, and of structural units ∆ (compacted) under conventional tillage and no-tillage. The soil was increasingly degraded in the increasing order: forest => no-tillage crop rotation => perennial crop => no-tillage without crop rotation => conventional tillage. In all managements, the values of organic matter and macroporosity were always below and bulk density always above those of the reference area (forest) and, under no-tillage crop rotation and perennial crop, the flocculation degree was proportionally equal to that of the reference area.

Enhanced degradation of metalaxyl in agricultural soils of São Paulo State, Brazil

This work investigated the effect of repeated applications on enhanced degradation of metalaxyl in two different agricultural soils used for cultivation of orange and lemon from Casa Branca and Itapetininga districts of São Paulo State, Brazil. Soil samples were collected from areas repeatedly treated with commercial ridomil 50GR for six successive years, and from other areas never exposed to this fungicide. At the laboratory, soil samples received a 14C-metalaxyl solution and its degradation was studied through radiometric techniques to measure biomineralization and recovery of extractable- and soil-bound products. Enhanced degradation was verified only in one soil, although partial degradation and mineralization of the fungicide were detected in both soils. The different rates and patterns of metalaxyl degradation in the soils were probably due to their different physical, chemical, and biological characteristics.

Água aquecida e radiação UV-C no controle pós-colheita de Cryptosporiopsis perennans em maçãs

O objetivo deste trabalho foi avaliar a colonização de Cryptosporiopsis perennans na epiderme de maçãs e a eficiência da aplicação de água aquecida e radiação UV-C no controle desse patógeno. Em maçãs submetidas à inoculação de C. perennans, a colonização de lenticelas e das áreas adjacentes pelo patógeno foi avaliada por microscopia eletrônica de varredura. A sensibilidade dos conídios de C. perennans aos tratamentos foi avaliada em suspensão aquosa, às temperaturas de 28, 45, 50 e 55ºC, por 15 e 30 s, e às doses de radiação UV-C de 0,018, 0,037, 0,075, 0,150, 0,375, 0,750, 1,500 e 3,000 kJ m-2. Em maçãs submetidas à inoculação de C. perennans, foram avaliados os efeitos de 0,375, 0,750 e 1,500 kJ m-2 de radiação UV-C e da aspersão de água aquecida à 50ºC, por 15 e 30 s no controle do patógeno. O fungo produziu abundante micélio e conídios nas lenticelas e nas áreas adjacentes, na epiderme das maçãs. A água aquecida a 50ºC por 15 s e à dose de radiação de UV-C de 0,750 kJ m-2 reduzem em mais de 99% a sobrevivência de conídios. A aspersão de água aquecida a 50ºC por 15 s e à dose de radiação de UV-C de 0,375 kJ m-2, controlam C. perennans em maçãs.

Functional diversity of bacterial genes associated with aromatic hydrocarbon degradation in anthropogenic dark earth of Amazonia

The objective of this work was to evaluate the catabolic gene diversity for the bacterial degradation of aromatic hydrocarbons in anthropogenic dark earth of Amazonia (ADE) and their biochar (BC). Functional diversity analyses in ADE soils can provide information on how adaptive microorganisms may influence the fertility of soils and what is their involvement in biogeochemical cycles. For this, clone libraries containing the gene encoding for the alpha subunit of aromatic ring-hydroxylating dioxygenases (α-ARHD bacterial gene) were constructed, totaling 800 clones. These libraries were prepared from samples of an ADE soil under two different land uses, located at the Caldeirão Experimental Station - secondary forest (SF) and agriculture (AG) -, and the biochar (SF_BC and AG_BC, respectively). Heterogeneity estimates indicated greater diversity in BC libraries; and Venn diagrams showed more unique operational protein clusters (OPC) in the SF_BC library than the ADE soil, which indicates that specific metabolic processes may occur in biochar. Phylogenetic analysis showed unidentified dioxygenases in ADE soils. Libraries containing functional gene encoding for the alpha subunit of the aromatic ring-hydroxylating dioxygenases (ARHD) gene from biochar show higher diversity indices than those of ADE under secondary forest and agriculture.

Tratamentos hidrotérmico e com radiação UV-C no controle pós-colheita da podridão olho-de-boi em uma linha comercial de seleção de maçãs

Avaliaram-se os efeitos da aspersão hidrotérmica e da radiação UV-C no controle pós-colheita da podridão olho-de-boi (POB) em maçãs 'Fuji', após um e oito meses de armazenamento, e 'Gala', após cinco meses de armazenamento, ambas sob condição de atmosfera controlada (AC). Esses frutos foram inoculados ou mantidos com infecção natural de Cryptosporiopsis perennans. As maçãs 'Fuji' foram submetidas aos seguintes tratamentos, aplicados em uma linha comercial de seleção: sem tratamento (testemunha); aspersão hidrotérmica (água a 50ºC por 12 segundos); radiação UV-C (0,0069 kJ m-2); e aspersão hidrotérmica + radiação UV-C. As maçãs 'Gala' também foram submetidas a estes tratamentos utilizados em 'Fuji', exceto ao tratamento com aspersão hidrotérmica + radiação UV-C. Após os tratamentos, as maçãs foram incubadas a 22ºC por 15 dias e avaliadas quanto à incidência da doença. Nas maçãs 'Fuji', os tratamentos de aspersão hidrotérmica e/ou radiação UV-C reduziram a incidência da POB nos frutos inoculados e com infecção natural, proporcionando controle superior a 56% e 54%, em relação à testemunha, respectivamente. Em maçãs 'Gala' inoculadas, os tratamentos com aspersão hidrotérmica e radiação UV-C também reduziram o número de unidades formadoras de colônias (UFC) nos frutos, com controle superior a 70%, e a incidência da POB, com controle superior a 69% em relação à testemunha. Em maçãs 'Gala', com infecção natural, estes tratamentos apresentaram controle da POB superior a 85% em relação à testemunha. Os resultados obtidos mostram que os tratamentos com aspersão hidrotérmica e/ou radiação UV-C reduzem a incidência da POB em maçãs 'Fuji' e 'Gala', em linha comercial de seleção. Todavia, o uso da radiação UV-C, em ambas as cultivares, foi o tratamento que apresentou maior benefício e retorno econômico.

Fenólicos totais, polifenoloxidade e coloração em abacate 'Hass' submetido a radiação UV-C

Avaliou-se o efeito da radiação UV-C em abacates Hass, quanto ao conteúdo de fenólicos totais, atividade da enzima polifenoloxidase (PPO) e coloração. Os frutos selecionados foram submetidos à radiação em luz UV-C durante 5; 10; 15 e 20 minutos, sendo mantidos sob refrigeração (10 ± 1 ºC e 90±5% UR), e avaliados durante 15 dias. Para o teor fenólicos totais e PPO, não se observou diferença entre os tratamentos dos frutos nos diferentes tempos de exposição à luz UV-C. Os teores fenólicos totais e PPO diminuíram durante o período experimental. Os valores de luminosidade mantiveram-se elevados (85,4 a 88,5) no armazenamento. Os valores de cor a* e b* diminuíram com o armazenamento de forma mais intensa para os frutos submetidos à radiação UV-C. Não houve correlação significativa para a PPO, conteúdo de fenólicos totais e coloração.

PREVENTION OF CHILLING INJURY IN 'TOMMY ATKINS' MANGOES PREVIOUSLY STORED AT 5 ºC, USING HEAT TREATMENT AND RADIATION UV (UV-C)

ABSTRACT The objective of this study was to evaluate the effect of heat treatment and ultraviolet radiation (UV-C) in the prevention of chilling injury in mangoes cv. Tommy Atkins previously stored or not under injury condition after their transference to ambient condition. Fruits were divided into groups: two were hydrothermally treated (46.1 ºC/90 min; 55 ºC/5 min) and two were exposed to UV-C radiation (1.14 kJ m-2; 2.28 kJ m-2). These groups were stored under chilling injury conditions (5 ºC for 14 days), as established in preliminary tests. Other untreated groups were stored at 12 ºC or 5 ºC. After the storage period, they were transferred to ambient conditions (21.9 ºC; 55% RH) and the quality was evaluated. All the data were submitted to multivariate analysis as the tool to verify the simultaneous effect of the treatments under the quality parameters. The multivariate analysis indicated that the hydrothermal treatments at 46.1 °C/90 min and 55 °C/5 min and the UV-C radiation at doses of 1.14 kJ m-2 and 2.28 kJ m-2 were effective in minimized the symptoms of chilling injury in mangoes ‘Tommy Atkins’ stored at 5 °C for 14 days. However, after their transference to environmental condition at 21.9 °C, only the UV-C kept this control, especially at a dose of 2.28 kJ m-2. This treatment did not prevent the development of the characteristic color or affected the normal ripening and allowed the conservation of fruit for a period of 14 days at 5 °C, plus seven days of storage at environmental condition, which corresponds to the shipping transportation plus the time for sale.

Degradation of the surface of a metasilicate glass due to atmosphere moisture

Glasses with low silica content are very susceptible to suffer pronounced degradation when exposed to room atmosphere during short times. In this work the results of the degradation of the surface of a metasilicate glass with composition 2Na2O.1CaO.3SiO2 are presented. Optical and scanning electron microscopy observations, X-ray diffraction, infrared and Raman microprobe spectroscopic measurements of the modified surface of this glass show strong evidences that it is formed essentially by a crystalline carbonate layer.

Análise multicomponente simultânea por espectrofotometria de absorção molecular UV-VIS

This review presents the evolution of simultaneous multicomponent analysis by absorption spectrophotometry in the ultraviolet and visual regions in terms of some qualitative and quantitative analysis techniques, otimization methods, as well as applications and modern trends.

A simplified procedure for determination of clofentezine residues in fruits by liquid chromatography with UV detection

A rapid and sensitive method is described for the determination of clofentezine residues in apple, papaya, mango and orange. The procedure is based on the extraction of the sample with a hexane:ethyl acetate mixture (1:1, v/v) and liquid chromatographic analysis using UV detection. Mean recoveries from 4 replicates of fortified fruit samples ranged from 81% to 96%, with coefficients of variation from 8.9% to 12.5%. The detection and quantification limits of the method were of 0.05 and 0.1 mg kg-1, respectively.

Estratégias para aumento de sensibilidade em espectrofotometria UV-VIS

Spectrophotometry is one of the most widespread analytical techniques due to its simplicity, reliability, and low-cost instrumentation for both direct measurements and coupled to other techniques or processes such as chromatography, electrophoresis and flow analysis. However, the application is often limited by sensitivity. This article describes some advances that greatly improve the performance of spectrophotometric measurements, especially in order to increase sensitivity, including the employment of liquid-core waveguides and solid-phase spectrophotometry.

Degradação de BTXs via processos oxidativos avançados

In this study the efficiency of advanced oxidative processes (AOPs) were investigated toward the degradation of aqueous solutions containing benzene, toluene and xylenes (BTX). The results indicated that BTX can be effectively oxidized by the UV-A-assisted photo-Fenton process. The treatment permits almost total degradation of BTX and removal of more than 80% of the phenolyc intermediates at reaction times of about 30 min. Preliminary investigations using solar light suggest a good potentiality of the process for the treatment of large volumes of aqueous samples containing these polluting species.

Imobilização de TiO2 em concreto: fotodegradação de clorofórmio e fenol

TiO2 immobilization on concrete was studied using mixtures with cement, varnish and resin. The UV radiation sources were a germicide UV lamp and solar light. Aqueous solutions of chloroform (CHCl3) and of phenol were prepared and recirculated over the TiO2 immobilized surfaces. The immobilized TiO2 surfaces showed better photocatalytic efficiency for phenol degradation compared to the control. For CHCl3, the presence or absence of the catalyst did not cause any significant difference to its degradation efficiency. The micrographic results showed a more homogeneous surface for TiO2 immobilized in resin and varnish.