Maria Diva Landgraf

Estudo da adsorção/dessorção do ácido 2,4 diclorofenoxiacético (2,4d) em solo na ausência e presença de matéria orgânica

The herbicides are being used in huge quantities for various porpouses. Once the herbicide finds its way into the environment, a major part of it comes in contact with soil. Humic substances are major organic constituents of soil. These substances may interact with herbicides in different modes and adsorption is probably the most important one. Adsorption will control the quantity of herbicide in the soil solution, and determines its persistence, leaching, mobility and bioavailability. In this work we studied the interaction between the herbicide 2,4D and soil in the presence and absence of organic matter. The methodology utilized for the determination of 2,4D was gas chromatography with eletron capture detector. The behavior of 2,4D was evaluated through Freundlich isotherms. It was verified that the herbicide 2,4D has a large adsorption in the humic acid .

COMPORTAMENTO DOS HERBICIDAS ATRAZINA E ALACLOR APLICADOS EM SOLO PREPARADO PARA O CULTIVO DE CANA-DE-AÇÚCAR

Atrazine and alachlor herbicides are widely and extensively used in agriculture for the control of a variety of weeds. These herbicides are quite mobile in soil and there is a concern that they may contaminate the environment, specially surface and ground water and soils. The results suggest that alachlor and atrazine present similar behavior in the environment, but alaclhor dissipates with greater rate.

Caracterização de ácidos húmicos de vermicomposto de esterco bovino compostado durante 3 e 6 meses

The main objective of this research was the characterization of the humic fractions isolated from vermicomposting, originating from cattle manure and treated with Eisenea foetida or Lumbricus rubellus, during 3 and 6 months. Elemental analysis and Infrared and UV-vis spectroscopy were used for their characterizations. The results obtained shown that both humic acids are very similar, but six-month humic acid shown lower percentage of organic material than three month humic acid. The spectroscopy analysis shown that the humic acid studied can be compared with other humic acids reported in the literature. By comparing both vermicomposts, the one produced in three months presents a great potential as fertilizer and it is more economical than the vermicompost produced during a six month period.

Processo de estabilização de resíduos orgânicos: vermicompostagem versus compostagem

Two processes are used to stabilize organic wastes: composting and vermicomposting.There are no studies in the literature showing which process is most effective over the short term. In this study, 3 organic wastes were composted and vermicomposted for 90 days, and the parameters pH, effective cation exchange capacity, total organic carbon, total Kjeldahl nitrogen, Ptotal, E4/E6 ratio, hydrophobicity and aromaticity indexes were determined. In all experiments, vermicomposted materials showed higher stability, proving a superior tool for stabilization of these organic wastes.

Determination of Pentachlorophenol and Hexachlorobenzene in Natural Waters Affected by Industrial Chemical Residues

Este trabalho teve como principal objetivo o desenvolvimento de uma metodologia para a analise simultânea de pentaclorofenol (PCP) e hexaclorobenzeno (HCB) em agua natural de subsuperficie proveniente de uma regiao afetada por residuos industriais (Sao Vicente-SP), onde a maior parte da populacao se utiliza de pocos pouco profundos para o abastecimento. A extracao liquido-liquido apresentou bons resultados quanto a recuperacao e repetibilidade do metodo. Para o nivel de fortificacao de 10 ng L-1 de PCP e HCB a recuperacao situou-se entre 81.5% e 103.0%, com um desvio padrao relativo de 2.4% a 4.1%. A determinacao dos analitos foi efetuada por GC-ECD e/ou GC-MS. Adicionalmente, o limite de quantificacao do metodo foi de 5 ng L-1 para PCP e 2 ng L-1 para HCB, valores que estao abaixo do nivel maximo permitido pelas diretrizes da Comunidade Europeia para residuos de pesticidas em agua potavel.

Optimization of parameters for the gas chromatographic determination of polycyclic aromatic hydrocarbons

Abstract The optimization of conditions for the gas chromatographic determination of sixteen polycyclic aromatic hydrocarbons (PAHs) using the splitless injection mode is described. Parameters optimized were the type and amount of solvent, the temperature of the injection port and the column and the purge time. A factorial design was used initially to identify the most important parameters. Based on this initial study, xylene was chosen as the solvent and 100°C was chosen as the best value for temperature of the column. The other parameters were optimized by using a simplex method. The optimum conditions found were 3 μl of solvent, 280°C for the injection port and a purge time of 30 s. With these conditions, relative standard deviations for five replicate determinations of 2-ng amounts of PAHs were 3.2–10.8%.

SORPTION AND DESORPTION OF THE HERBICIDE ALACHLOR ON HUMIC ACID FRACTIONS FROM TWO VERMICOMPOSTS

The present study focuses on the analysis of two vermicomposts, that have been used as alternative sources of restitution of soil organic matter, as well as sources of nutrient replacements. For this purpose, two samples of vermicom-posts from different Brazilian regions (São Carlos—SP and Londrina—PR) were characterized according to their humic acid content. Both samples had a pH value near 7.0, and the humic acids present showed high cationic exchange capacities and low values for the C/N ratios. The infrared spectra showed bands that suggested the presence of aliphatic and aromatic components bound to phenolic, carboxylic and amide groups. The effect of vermicompost added to soil on the application of alachlor was evaluated. Alachlor sorption, Freundlich isotherms and alachlor desorption curves in the soil matrix and the vermi-compost/soil mixture matrix were determined.

Acompanhamento químico da vermicompostagem de lodo de esgoto doméstico

the final product (vermicompost) in agricultural soils. The monitored chemical variables during the 90 days of vermicomposting were: humidity rate, organic matter content, nitrogen and phosphorus content, pathogenic organisms concentration, total organic carbon, acidity, CEC, C/N ratio, CEC/TOC ratio, and humic and fulvic acids content. The change in these variables during the vermicomposting process showed that this technique is effective for use in the maturation of the residue.

Chemical Differentiation of Domestic Sewage Sludge and Cattle Manure Stabilized by Microbioreators: Study by Pyrolysis Coupled to Gas Chromatography Coupled to Mass Spectroscopy

The aim of the present study was to evaluate the chemical alterations in substrates of vermicomposts from domestic sewage sludge and from cattle manure, besides its quality as an organic fertilizer. Elemental and infrared analysis and UV-Vis spectroscopy were used for their characterizations. Chemical characteristics determined in the vermicomposts indicate that they can be used as organic fertilizers, mainly with regard to organic matter content, pH, C/N ratio, and nitrogen and phosphorus levels. The main constituents of the humic substances extracted from the vermicomposts were obtained by pyrolysis coupled to gas chromatography-mass spectrometry (GC/MS), showing that these compounds are quite similar, despite being produced by domestic sewage sludges or by cattle manure.

Determination of Organochlorine Pesticides Dissolved in Water: A Comparison Between Solid Phase and Solvent Extraction

Abstract Sixteen organochlorine pesticides (EPA priority) were spiked into water at a concentration range of 20 ng/L to 20,000 ng/L and then extracted by utilizing solid phase techniques and the method 608 of EPA. The solid phases XAD-2 and C-18 were studied. The reverse phase C-18 presented a recovery of about 85%, except for heptachlor and aldrin. The solvent extraction showed better recovery in concentrations higher or equal to 200ng/L for about all pesticides. We concluded that both methods showed good recoveries. Nevertheless, the solvent extraction is time consuming, the apparatus is cumbersome and large volumes of solvents are required while the solid phase extraction (SPE) is quick, low solvent consuming and sometimes achieving higher sensitivity than solvent extraction. Both methods were used and compared to determine organochlorine pesticides in a river from the state of Sao Paulo, Brazil.