The contamination of water bodies by pesticide residues through direct flow, leaching and other methods has motivated the development of analytical methods for the determination of these compounds in water. A vortex-assisted liquid-liquid microextraction method followed by gas chromatography coupled to mass spectrometry for the determination of anilazine, linuron, prothiofos, and tebuconazole residues in water samples from the culture and processing of potatoes (Solanum tuberosum L.) was optimized. The complete factorial design and the central rotational compound design combined with the desirability function were used to evaluate and optimize the parameters of the method. The optimized conditions for extracting the pesticides were as follows: 316 µL of toluene, no sodium chloride addition, and a stirring time of 187 s. The method presented an enrichment factor of 142.4 times and good linearity, precision and accuracy, with limits of detection (LOD) of 0.005 - 0.007 mg L-1 and limits of quantification (LOQ) of 0.016 - 0.022 mg L-1. The co-extractives of the wastewater samples caused the suppression of the chromatographic response of linuron and prothiofos by 7.82 and 27.63%, respectively. The analyte concentrations in the wastewater samples from the industrial shing process, manual potato washing, and dam water were either lower than the LODs of the method or were absent.

Birnessite type manganese oxide (δ-MnO2) was synthesized for use in degradation of the cationic dye methylene blue in aqueous solution. The material was characterized using infrared spectroscopy, X-ray diffraction, and Brunauer-Emmett-Teller (BET) surface area calculations. The removal of the dye from aqueous solutions was evaluated considering the effects of the following variables: pH, manganese oxide concentration, contact time, and temperature. UV-Vis spectroscopy analyses indicated achievement of 99 and 95% removal of methylene blue (7 mg L-1) at pH 2.0 and 4.0, respectively, after 120 min of contact with the birnessite (100 mg L-1). At higher pH of 6.0 and 8.0, removals of around 99 and 80%, respectively, were obtained after a longer time of 1860 min. Analyses of total organic carbon (TOC) revealed that 80% reduction of organic matter was obtained at pH 4.0. The method of multivariate curve resolution-alternating least squares (MCR-ALS) was used together with UV-Vis spectroscopy to evaluate the removal process, confirming the degradation of methylene blue. Thionine (λmax = 601 nm) was identified as one of the byproducts of N-demethylation of methylene blue. The results indicated that the degradation process started with N-demethylations of the methylene blue molecule.

Clomazone exhibits high water solubility, low sorption in soil colloids, and therefore can leach and contaminate deep layers of soil profile and groundwater. In this work, the effect of the incorporation of sugarcane bagasse biochar in leaching and bioavailability of clomazone in red latosol was evaluated. Soil samples amended with 1% (m/m) biochar were placed in different depths (0-1, 0-2.5 and 0-5 cm) on the top of polyvinyl chloride (PVC) columns filled with soil. Clomazone-based herbicide was applied, and rainfall was simulated on top of the columns. A validated chromatographic method, together with a greenhouse bioassay, were used to quantify and to evaluate the mobility and availability of clomazone along the columns. The incorporation of sugarcane bagasse biochar in the superficial layers at the column tops increased herbicide sorption, reduced its leaching and bioavailability in soil and scaled down the environmental risk of clomazone avoiding contamination of underground aquifer reservoirs.

Two types of manganese oxide were investigated for the removal/degradation of Orange G (OG) dye in aqueous solution. One manganese oxide (pyrolusite) was obtained commercially and the other (birnessite) was prepared according to the polyol method by means of the oxidation of MnII hydroxide by H2O2. Both materials were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM), and nitrogen adsorption/desorption at 77 K. The effects of agitation time, pH, and MnO2 dose on the degradation of OG by the birnessite and pyrolusite were evaluated. Approximately 90 and 99% decoloration of OG (10 mg L-1) was obtained after 30 min of stirring with 0.20 g L-1 of birnessite or pyrolusite, respectively. The decoloration and increased intensity of absorbance bands in the UV-visible spectrum were indicative of a degradation process that followed pseudo-first order kinetics. The findings demonstrated the high efficiency of different types of manganese oxides for removal of this organic pollutant from waters.

RESUMO Objetivou-se neste trabalho avaliar a remediação de água contendo o inseticida clorpirifós, por meio de sistemas alagados construídos (SAC) cultivados com as espécies Polygonum punctatum, Cynodon spp. e Mentha aquatica operados sob diferentes tempos de retenção hidráulica: 24, 48, 96, 144 e 192 h. A eficiência do sistema foi baseada na redução da concentração inicial do clorpirifós e toxicidade da água contaminada. Os resultados mostraram que os sistemas alagados construídos são uma excelente alternativa na biorremediação do inseticida clorpirifós no meio aquoso. Observou-se média geral de eficiência na remoção do inseticida de 98,6%, sendo que no primeiro tempo de retenção hidráulica, 24 h, houve remoção do clorpirifós para valores inferiores ao limite detecção para todos os SAC. Tal resultado é atribuído principalmente aos processos de adsorção e degradação microbiana. Para os ensaios padronizados qualitativos de toxicidade aguda com Daphnia similis, para a maioria das amostras observou-se a redução de toxicidade acima de 80%. Constatou-se que os testes ecotoxicológicos com os efluentes dos sistemas alagados construídos estudados são uma boa opção como indicativo da eficiência dos tratamentos e uma promissora alternativa na complementação de análises físicas e químicas.

ABSTRACT The objective of this study was to evaluate the remediation of water containing the insecticide chlorpyrifos by using constructed wetlands (CW) cultivated with Polygonum punctatum, Cynodon spp. and Mentha aquatica, operated under different hydraulic retention times: 24, 48, 96, 144 and 192 h. The system efficiency was based on reduction of the initial concentration of chlorpyrifos and toxicity of the contaminated water. The results showed that constructed wetlands are an excellent alternative for remediation of the insecticide chlorpyrifos in aqueous medium. It was observed that the average overall removal efficiency of the insecticide was 98.6%, and in the first hydraulic retention time, 24 h, chlorpyrifos was removed to levels below the detection limit in all CW. This result is mainly attributed to adsorption and microbial degradation. For the qualitative standard acute toxicity tests with Daphnia similis, for most samples there was a reduction in toxicity greater than 80%. It was reported that the ecotoxicological tests with the effluents of the constructed wetland are a good option as an indicator of the effectiveness of treatments and a promising alternative to complement the physical and chemical analyses.

A new method has been developed to determine trace levels of organophosphorus pesticide parathion-methyl in water samples by using dispersive liquid-liquid microextraction (DLLME), followed by gas chromatograph coupled with electron capture detector (GC/ECD) analysis. The optimized and validated method showed high extraction recovery (101.1%), high enrichment factor (57.3), low limits of detection and quantification, 0.083 and 0.250 µg L-1, respectively. The established DLLME-GC/ECD method has been successfully applied for the evaluation of the photodegradation of the parathion-methyl by UV254nm radiation in different conditions of pH and temperature. The parathion-methyl photodegradation at pH 3 and 35 °C achieved > 99.5% after 120 min of exposition. For this condition, it was observed the kinetic rate of 0.0515 min-1, the quantum yield of 1.22 × 10-5 mol Einstein-1 and a half-life time of 13.46 min. All experimental conditions tested proved to be strongly influenced by pH and temperature. The application of the optimized process in distilled and drinking water spiked with parathion-methyl provided residues of this pesticide at levels below the maximum permitted by Brazilian legislation, which is 9.0 µg L-1.

Various greener microextraction procedures have been proposed with low limits of detection to control of pesticides present in the environment, including the low-density solvent dispersive liquid‑liquid microextraction (LDS/DLLME) technique. The addition of electrolytes is important in order to induce the salting-out effect. Thus, it is possible to use the Hofmeister series and the Voet lyotropic number to study the effect of different ions on pesticide extraction in LDS/DLLME technique. Different anions were tested and a strong correlation was observed between the lyotropic number of the anion and the recovered volume of extraction solvent. The lyotropic numbers of the anions were successfully compared with the chromatographic peak areas normalized by the recovered solvent volumes, and similar empirical cubic relationships were obtained for all the pyrethroids evaluated. In the extraction of the organophosphorous pesticides, chlorpyrifos presented similarity with the pyrethroids, while correlation was observed between methyl parathion and profenofos.

A new method for the extraction of pesticide residues from soil was developed, optimized, validated and applied to real samples. The technique consisted of combining single-drop microextraction and solid-liquid extraction with low temperature partitioning (SLE/LTP-SDME) followed by analysis using gas chromatography with electron capture detection (GC/ECD). This method was used to determine the presence of alachlor, methyl parathion, trifluralin, endrin, lindane, dieldrin and dichloro-diphenyl-trichloroethane (4,4’-DDT) in soil samples. Recoveries ranging from 67.2 to 122.5% were achieved, coefficients of variation (repeatability) were lower than 22.4% and limits of detection ranged from 0.18 to 0.59 µg kg-1. Recovery from soils fortified with different concentrations of the pesticides ranged from 61.5 to 123.5%. The new method combines the primary advantages of the two techniques: purification of the sample using SLE/LTP and preconcentration using SDME. The new method also enables the determination of low volatility compounds without requiring the sample to be heated.

Due to uncontrolled use of pesticides and disregard for harvest intervals, some pesticide residue is present in various foods. Treatments using ozone as an alternative for food decontamination have been studied in recent years due to ozone’s high oxidation potential even at low concentrations. The present work aimed to evaluate chlorothalonil removal from table grapes by the immersion of fruit in distilled water continuously bubbled with ozone gas. This strategy allowed the removal of 60% of chlorothalonil from table grapes (pulp and skin), regardless of ozone concentration. Ozone treatment of table grapes at a gas concentration of 3 mg L−1 changed most of the quality parameters evaluated. Treatment at 2 mg L−1 maintained the fruit quality for a longer storage period compared to the untreated control table grapes.

O monitoramento de pesticidas em amostras ambientais em baixas concentrações é necessário devido aos riscos que estes compostos representam a saúde humana e ao meio ambiente. Neste trabalho, o método microextração em gota única (SDME) foi otimizado e validado para a determinação das concentrações traço de oito pesticidas em água utilizando cromatografia gasosa com detector por captura de elétrons (GC/ECD). A cinética de transferência de matéria da fase aquosa para a fase orgânica durante o processo de extração também foi avaliada. O método mostrou recuperações entre 89,5 e 122,7%, com coeficientes de variação menores que 22,9%, e os limites de detecção entre 5,9 e 58,9 ng L-1. O método foi aplicado a amostras fortificadas em diferentes níveis de concentração, e recuperações entre 50,5 e 148% foram obtidas. O processo de extração pode ser descrito pelo modelo de difusão de Noyes-Whitney, e a parationa metílica apresentou a maior taxa de transferência entre as duas fases.

The monitoring of pesticides in environmental samples at low concentrations is needed due to the risks that these compounds can pose to human health and the environment. In this work, a single drop microextraction (SDME) method was optimized and validated for the determination of trace concentrations of eight pesticides in water, using gas chromatography with electron capture detector (GC/ECD). The kinetics of the transfer of material from the aqueous phase to the organic phase during the extraction process was also evaluated. The method showed recoveries between 89.5 and 122.7%, with coefficients of variation smaller than 22.9%, and detection limits between 5.9 and 58.9 ng L-1. The method was applied to spiked samples at different concentration levels, and recoveries between 50.5 and 148% were obtained. The extraction process could be described by the Noyes-Whitney diffusion model, and methyl parathion showed the highest rate of transfer between the two phases.

Nove sistemas alagados (SACESHs) foram construídos em escala piloto (1,5 m de comprimento, 0,5 de largura e 0,4 m de profundidade), cultivados com Typha sp. e Alternanthera phyloxeroides, e operados sob diferentes taxas de aplicação orgânica, no tratamento da água residuária do processamento dos frutos do cafeeiro (ARC). Três sistemas receberam ARC sem nenhum pré-tratamento, em três foi aplicada ARC com correção de pH e correção nutricional e nos três últimos os efluentes de filtros anaeróbios utilizados no tratamento da ARC, que teve o pH e o teor de nutrientes corrigidos. Os resultados mostraram que o aumento nas taxas de carga superficial dos constituintes da ARC no sistema proporcionou decréscimo na eficiência de remoção de matéria orgânica e compostos fenólicos, em todos os SACESHs avaliados. Os tempos de detenção hidráulica superiores a 100 h proporcionaram maiores eficiências na remoção de DQO (SAC*1, SAC F1 e SAC F2) e DBO (SAC1, SAC*1, SAC F2 e SAC F3) que os tempos de detenção hidráulica de aproximadamente 60 h aplicados nas fases iniciais do experimento. Entre os SACESHs, o SAC F1, que recebeu a menor taxa de aplicação orgânica (1.500 kg ha-1 d-1 de DQO), apresentou desempenho mais satisfatório no que se refere à remoção de DBO (63%), DQO (85%) e compostos fenólicos (65%).

Nine constructed wetlands (SACESHs) were built on a pilot scale (1.5 m long, 0.5 wide and 0.4 m deep), grown with Typha sp. and Alternanthera phyloxeroides, and operated under different organic loads in the treatment of wastewater of coffee processing (ARC). Three systems received no ARC pre-treatment, three received ARC with correction of pH and nutritional correction, and the last three received the effluent of filters used in the anaerobic treatment of ARC that had the pH and nutrient content corrected. The results showed that the increase in the rate of surface charge of the constituents of the ARC provided the decrease in efficiency of removal of all SACESHs evaluated. The hydraulic detention time of more than 100 h provided higher efficiencies in the removal of COD (SAC*1, SAC F1 and SAC F2) and BOD (SAC1, SAC*1, SAC F2 and SAC F3) than hydraulic detention times of approximately 60 h implemented in the early stages of the experiment. Among SACESHs the SAC F1, which received the lowest organic load (1500 kg ha-1 d-1 of COD), showed a satisfactory performance with regard to the removal of BOD (63%), COD (85%) and phenolic compounds (65%).

A técnica de seca-aeração pode causar problema no controle de insetos devido à alta temperatura do grão durante o processo de pulverização do inseticida. Com este trabalho objetivou-se avaliar o efeito imediato e latente da temperatura do grão durante o processo de pulverização sobre a persistência e eficácia biológica do inseticida pirimifós-metil no controle de Sitophilus zeamais e Tribolium castaneum. Para tal, pulverizou-se o inseticida pirimifós-metil sobre os grãos de milho quando se apresentavam nas temperaturas de 25, 30, 35, 40 e 45 °C. A análise de resíduo foi realizada após a pulverização e a cada 30 dias, até 90 dias. Para avaliação da eficácia biológica 20 insetos adultos de S. zeamais e de T. castaneum foram colocados em uma placa de Petri contendo grãos tratados e, após 48 h de exposição dos insetos aos grãos, logo depois da pulverização e a cada 15 dias, até 90 dias, foram realizadas as avaliações. Observou-se que a eficácia biológica do pirimifós-metil reduziu durante o período de armazenamento e que o aumento da temperatura do grão no momento da pulverização também contribui para a redução da eficácia deste inseticida. Observou-se, também, que S. zeamais apresentou menor sensibilidade ao pirimifós-metil que T. castaneum.

The expansion of dryeration may impose a further problem for insect control with protectants - the high grain temperatures during insecticide spraying. To assess the impact of this procedure on insecticide activity, maize grains at different temperatures (25, 30, 35, 40 and 45 °C) were sprayed with pirimiphos-methyl. Residue analyses were carried out every 30 days and insecticide biological activity towards Sitophilus zeamais and Tribolium castaneum was assessed every 15 days throughout the experimental period of 90 days. Insect mortality was evaluated after 48 h. Pirimiphos-methyl residue decreased with increased storage time and grain temperature during spraying. Similar trends were also observed for mortality of S. zeamais and T. castaneum, which dropped from around 100% for lower grain temperatures, shortly after spraying, to mortality values around 0% for higher temperatures and after 90 days of storage. These results indicate the drastic effect of grain temperatures during spraying, which compromises the efficiency of grain protectants for insect pest control on stored grains.