Poluição das águas por herbicidas utilizados no cultivo do arroz irrigado na região central do estado do Rio Grande do Sul, Brasil: predição teórica e monitoramento Pollution of water by herbicides used in the irrigated rice cultivation in the central area of Rio Grande do Sul state, Brazil: theoretical prediction and monitoring

This article presents an evaluation of the pollution of river water by herbicides used in the culture of irrigated rice in Rio Grande do Sul State, Brazil. Firstly, a theoretical evaluation was made using the approaches suggested by EPA-USA, the "Groundwater Ubiquity Score" index and the Goss method to estimate the pollution possibilities. Afterwards, a monitoring program was established for the rivers of the area from 2001 to 2003 to investigate the presence of herbicide residues. The results indicate that the herbicides clomazone and propanil are the ones with larger presence and frequency in the analyzed samples. The theoretical forecast was confirmed by the results of the monitoring program

Pollution of water by herbicides used in the irrigated rice cultivation in the central area of Rio Grande do Sul state, Brazil: theoretical prediction and monitoring

Submitted by Paula Gautério ([email protected]) on 2014-02-26T23:29:35Z No. of bitstreams: 1 Poluição das águas por herbicidas utilizados no cultivo do arroz irrigado na região central do Estado do Rio Grande do Sul.pdf: 90417 bytes, checksum: 4ebf473ca52ef771d4c452458f602493 (MD5)Approved for entry into archive by cristiane soares ([email protected]) on 2014-07-22T17:12:20Z (GMT) No. of bitstreams: 1 Poluição das águas por herbicidas utilizados no cultivo do arroz irrigado na região central do Estado do Rio Grande do Sul.pdf: 90417 bytes, checksum: 4ebf473ca52ef771d4c452458f602493 (MD5)Made available in DSpace on 2014-07-22T17:12:20Z (GMT). No. of bitstreams: 1 Poluição das águas por herbicidas utilizados no cultivo do arroz irrigado na região central do Estado do Rio Grande do Sul.pdf: 90417 bytes, checksum: 4ebf473ca52ef771d4c452458f602493 (MD5) Previous issue date: 2005This article presents an evaluation of the pollution of river water by herbicides used in the culture of irrigated rice in Rio Grande do Sul State, Brazil. Firstly, a theoretical evaluation was made using the approaches suggested by EPA-USA, the “Groundwater Ubiquity Score” index and the Goss method to estimate the pollution possibilities. Afterwards, a monitoring program was established for the rivers of the area from 2001 to 2003 to investigate the presence of herbicide residues. The results indicate that the herbicides clomazone and propanil are the ones with larger presence and frequency in the analyzed samples. The theoretical forecast was confirmed by the results of the monitoring program

Poluição das águas por herbicidas utilizados no cultivo do arroz irrigado na região central do Estado do Rio Grande do Sul, Brasil: Predição teórica e monitoramento

This article presents an evaluation of the pollution of river water by herbicides used in the culture of irrigated rice in Rio Grande do Sul State, Brazil. Firstly, a theoretical evaluation was made using the approaches suggested by EPA-USA, the “Groundwater Ubiquity Score” index and the Goss method to estimate the pollution possibilities. Afterwards, a monitoring program was established for the rivers of the area from 2001 to 2003 to investigate the presence of herbicide residues. The results indicate that the herbicides clomazone and propanil are the ones with larger presence and frequency in the analyzed samples. The theoretical forecast was confirmed by the results of the monitoring program

A Gas Chromatographic Method for the Determination of the Fungicide Chlorothalonil in Tomatoes and Cucumbers and its Application to Dissipation Studies in Experimental reenhouses

Desenvolveu-se e validou-se um novo método para avaliar os níveis de resíduo e a dissipação do fungicida clorotalonil em tomates e pepinos cultivados em estufas experimentais. Os vegetais foram submetidos a uma única pulverização com clorotalonil em meia dose, dose recomendada e dobro da dose. Os resíduos de clorotalonil foram extraídos em sistema Ultra-Turrax empregando acetato de etila na presença de sulfato de sódio anidro e determinados por cromatografia gasosa com detecção por captura de elétrons. As curvas analíticas foram lineares de 0,005 a 5,0 mg L-1, com coeficiente de determinação maior que 0,995. Os ensaios de precisão fornecem resultados aceitáveis com valores de RSD abaixo de 10,5% e recuperações entre 92,2 e 114,5% para tomate, e entre 86,2 e 103,3% para pepino, ambos obtidos para níveis de fortificação 0,028, 0,28, 2,8 e 5,0 mg kg-1. A interpretação estatística dos níveis de resíduo indicou um modelo de primeira ordem para o comportamento da dissipação do clorotalonil. O tempo médio de meia-vida para o tratamento na dose recomendada, nos dois anos experimentais, foram 8,8 dias para tomate e 1,6 dia para pepino. A taxa mais elevada da diminuição de resíduos de clorotalonil em pepino é devida, principalmente, à taxa de crescimento mais elevada deste vegetal com relação ao tomate. O método desenvolvido provou ser eficiente para a determinação de resíduos de clorotalonil em tomate e pepino até o nível de 0,02 mg kg-1, permitindo avaliar o risco da exposição do consumidor.A new method to evaluate the levels of residue and the dissipation of chlorothalonil fungicide in tomatoes and cucumbers grown in experimental greenhouses was developed and validated. The vegetables were submitted to a single spraying with chlorothalonil at half, equal to and double of the recommended dose. Chlorothalonil residues were extracted in Ultra-Turrax system using ethyl acetate in the presence of anhydrous sodium sulphate and determined by gas chromatography with electron capture detection. The analytical curves were linear from 0.005 to 5.0 mg L-1, with coefficient of determination higher then 0.995. The assays provide acceptable results with RSD values below 10.5% and recoveries were between 92.2 and 114.5% for tomatoes, and between 86.2 and 103.3% for cucumbers, both obtained from spiked samples at 0.028, 0.28, 2.8 and 5.0 mg kg-1 levels. Statistical interpretation of residue levels fitted to a first-order model for the dissipation behavior of chlorothalonil. The mean half-life after treatments at the recommended dose, in the two experimental years, was 8.8 days for tomatoes and 1.6 days for cucumbers. The higher decrease rate of chlorothalonil residues in cucumbers is mainly due to the higher growth rate of this vegetable relative to tomato. The developed method has proven to be efficient for the determination of chlorothalonil residues in tomatoes and cucumbers with a limit of quantification of 0.02 mg kg-1 level, permitting to evaluate the risk of consumer exposure to these residues

Risk Assessment of Surface Water Contamination by Herbicide Residues: Monitoring of Propanil Degradation in Irrigated Rice Field Waters using HPLC-UV and Confirmation by GC-MS

O estudo avalia a degradação do herbicida propanil e de seu principal produto de degradação, a 3,4-dicloroanilina (3,4-DCA), em água de irrigação de lavouras de arroz irrigado no Estado do Rio Grande do Sul, Brasil. Além disso, estima, também, o risco de contaminação das águas de superfície das proximidades. Após uma etapa de extração em fase sólida, a concentração de ambos os compostos foi determinada por cromatografia líquida de alta eficiência com detecção na região do ultravioleta. A confirmação foi realizada por cromatografia gasosa-espectrometria de massas. A concentração de propanil nas amostras de água variou de 0,1 a 3600 μg L-1. O propanil degradouse rapidamente em 3,4-DCA, sendo que altas concentrações deste produto foram encontradas, variando entre 1,0 e 567,5 μg L-1. Os tempos de meia-vida para o propanil em água sob condições reais nas safras de 2001, 2002 e 2003 foram 18,2, 12,5 e 12,2 h, respectivamente.This study evaluates the degradation of the herbicide propanil and of its major degradation product, 3,4-dichloroaniline (3,4-DCA) in water from irrigated rice farming in the State of Rio Grande do Sul, Brazil. It also assesses the contamination risk of surrounding surface waters. After a solid phase extraction step, the concentration of both compounds was determined by high performance liquid chromatography with ultraviolet detection. Confirmation was conducted by gas chromatography-mass spectrometry. Concentrations of propanil in water samples varied from 0.1 to 3600 μg L-1. Propanil was degraded very rapidly to 3,4-DCA and high concentrations of this product were found, varying from 1.0 to 567.5 μg L-1 in water. The obtained half-life times for propanil in water under real conditions for the 2001, 2002 and 2003 harvests were 18.2, 12.5 and 12.2 h, respectively

Rapid and accurate HPLC-DAD method for the determination of the herbicide bispyribac-sodium in surface water, and its validation

A new method is described for the determination of the herbicide bispyribac-sodium in surface water, especially from river and irrigated rice water samples. The method involves extraction in solid phase and quantification by high performance liquid chromatography with diode array detection (HPLC-DAD). After optimization of the extraction and separation parameters, the method was validated. The method presented average recoveries of 101.3 and 97.7%, under repeatability and intermediate precision conditions, respectively, with adequate precision (RSD from 0.9 to 7.5%). The method was applied for the determination of bispyribac-sodium in surface water samples with a limit of detection of 0.1 μg L-1

Evaluation of ASTM D6584 Method for Biodiesel Ethyl Esters from Sunflower Oil and Soybean/Tallow Mixture and for Biodiesel Methyl Esters from Tung Oil and Soybean/Tung Mixture

This study describes for the first time the determination of glycerol and glycerides in samples of biodiesel ethyl esters from sunflower oil and soybean/tallow mixture and biodiesel methyl esters from soybean/tung mixture and tung oil by employing ASTM D6584 method. The results showed that ASTM D6584 can be used for other sources of biodiesel which represent an alternative to biodiesel production, mainly in Brazil

Base/acid-catalyzed FAEE production from hydroxylated vegetable oils

In this study was developed a new methodology to produce fatty acid ethyl esters from castor oil. The base-catalyzed transesterification step was followed by on pot addition of sulfuric acid. That addition implicated the successful separation of FAEEs/glycerin phases due to soap breaking. The study was carried out through an experimental design where the variables studied in the first step were the molar ratio alcohol:oil and the catalyst amount in the transesterification process. As expected, the on pot addition of concentrated sulfuric acid yields FFAs that increase the acid value in the FAEEs phase. A second step esterification of these free fatty acids from FAEE raw mixture was investigated. The esterification of FFA was carried out in 60:1 and 80:1 M ratios (alcohol:free fatty acids) and concentrated sulfuric acid 5% and 10% w/w (based on free fatty acids). Consequently, these two steps yielded more fatty ethyl esters and assure that the following important requirements in the FAEEs production process from castor oil are satisfied: complete reaction, best separation of FAEEs/glycerin phases, removal of catalyst, limpid glycerin, and absence of free fatty acid

Síntese de novas amidas graxas a partir da aminólise de ésteres metílicos

Recent biochemical and pharmacological studies have led to the characterization of different fatty acid amides as a new family of biologically active lipids. Here, we describe the synthesis of new amides from C16:0, 18:0, 18:1 and 18:1, OH fatty acids (FFA) families with cyclic and acyclic amines and demonstrate for the first time that these compounds produce citotoxic effects. Application of this method to the synthesis of fatty acid amides was performed using the esters aminolysis as a key step and various carboxylic amides were prepared in good yield from fatty acid methyl esters (FAMEs)