Efeitos de misturas de napropamide e simazine no controle de mono e dicotiledoneas em cafeeiros novos

Com a finalidade de se conhecer a a����o de misturas de napropamide e simazine no controle de plantas daninhas mono e dicotiled��neas em cafee iros com dois anos de idade, foi conduzido um experimento de campo em Araras, SP, em 1979/80. 0 delineamento foi o de blocos ao acaso com nove tratamentos e quatro repeti����es. Os tratamentos foram os seguintes: napropamide a 2,00 kg e 3,00 kg/ha; simazine a 0,50 kg e 0,75 kg/ha; e, misturas de 2,00 kg/ha de napropamide com 0,50 kg e 0,75 kg/ha de simazine, e de 3,00 kg/ha de napropamide tamb��m com 0,50 kg e 0,75 kg/ha de simaz ine . Constou do experimento ainda, uma testemunha sem herbicida. Aos 45 dias ap��s a aplica����o dos herbicidas foi feita uma contagem das plantas daninhas, e a cada 15 dias, at�� aos 90 dias da aplica����o, foram realizadas observa����es visuais de porcentagem de infesta����o do mato. Nestas mesmas ��pocas tamb��m foram realizadas observa����es sobre sintomas de fi totoxicidade causados pelos herbicidas aos cafeeiros. As plantas daninhas presentes em maior n��mero no ensaio foram as monocotiled��neas capim - de-colch��o - Digitaria horizontalis Willd e capimp�� -de-galinha Eleusine indica (L.1 Gaertn, e as dicotiled��neas carur��-de-mancha - Amaranthus viridis L. e pic��o-preto - Bidens pilosa L. Como era esperado, as misturas foram superiores aos tratamentos com herbicidas isolados. sendo bastante eficientes no controle das mono e dicotiled��neas que incidiram no experimento. Todos os tratamentos com 0.75 k ' ha de simazine apresentaram leves sintomas de fitotoxicidade, limitados a algumas folhas dos cafeeiros. at�� a ��ltima observa����o realizada.

PERSISTENCE OF ATRAZINE, METRIBUZIN AND SIMAZINE HERBICIDES IN TWO SOILS

An oat bioassay was conducted in pots under greenhouse conditions to determine the persistence of atrazine, metribuzin and simazine herbicides in soils of the southeast of Buenos Aires Province, Argentina. Atrazine rates of 0, 0.58, 1.16 and 2.32 mug g-1 of active ingredient (a.i.), metribuzin rates of 0, 0.14, 0.28 and 0.56 mug g-1 of a.i., and simazine rates of 0, 0.72, 1.45 and 2.9 mug g-1 of a.i. dry soil weight were applied to pots containing soils from Balcarce and San Cayetano sites. Organic matter (OM) content and pH of Balcarce soil were 5.5% and 5.8%, while for San Cayetano soil were 2.9% and 6.7%, respectively. Relative dry weight (RDW) of oat shoots was calculated as percentage of control. Considering a 20% RDW reduction of oat shoots, persistences of recommended rates for the region were: atrazine (1.16 mug g-1 of a.i.), 78 and 130 days after treatment (DAT) for Balcarce and San Cayetano soil, respectively; metribuzin (0.28 mug-1 of a.i.), 63 and 77 DAT for Balcarce and San Cayetano soil, respectively; simazine (1.45 mug g-1 of a.i.), 81 and 156 DAT for Balcarce and San Cayetano soil, respectively. Results show that persistence of atrazine, metribuzin and simazine in soil increased with high rates, low OM content and high pH.

Rainfall effect on dissipation and movement of diuron and simazine in a vineyard soil

From 2003 to 2007, a field study was performed in a vineyard in Chile to investigate diuron and simazine soil behavior and the effect of additional rainfall. Both herbicides were applied once a year at a rate of 2.0 kg ha-1 a.i. Herbicide concentrations in soil were measured at 0, 10, 20, 40, 90 and 340 days after application, under two pluviometric conditions, natural rainfall and natural rainfall plus irrigation with 180 mm of simulated rainfall during the first 90 days after application. Soil partition coefficient (Kd) varied in the soil profile (0 to 90 cm deep) from 6.75 to 2.04 mL g-1 and from 1.4 to 0.66 mL g-1 and the maximum soil adsorption capacity was approximately 18.3 mg g-1 and 8.3 mg g-1 for diuron and simazine, respectively. Diuron and simazine reached up to 90 and 120 cm of soil depth, with an average of 8.3% and 62.4% of herbicide moved below 15 cm in the soil, respectively. Simazine soil half-life (DT50) was 38.1 days and 7.5 days, whereas the half life for diuron varied from 68.0 and 24.6 for natural rainfall and irrigated, respectively. The average of residual simazine remaining in the whole soil profile after 90 DAA was 25.4% and 39.9% for diuron, with no effect of additional rainfall amount. At 340 DAA the amount of simazine in the whole soil profile corresponded to 13.2% of the initial amount applied, being diuron more persistent with 21.5% of the initial herbicide applied. The high movement in soil of both herbicides could be due to a non-equilibrium sorption process explained by preferential flow, low Kd and high desorption.

Transport and distribution of lindane and simazine in a riverine environment: measurements in bed sediments and modelling

Aquatic sediments often remove hydrophobic contaminants from fresh waters. The subsequent distribution and concentration of contaminants in bed sediments determines their effect on benthic organisms and the risk of re-entry into the water and/or leaching to groundwater. This study examines the transport of simazine and lindane in aquatic bed sediments with the aim of understanding the processes that determine their depth distribution. Experiments in flume channels (water flow of 10 cm s(-1)) determined the persistence of the compounds in the absence of sediment with (a) de-ionised water and (b) a solution that had been in contact with river sediment. In further experiments with river bed sediments in light and dark conditions, measurements were made of the concentration of the compounds in the overlying water and the development of bacterial/algal biofilms and bioturbation activity. At the end of the experiments, concentrations in sediments and associated pore waters were determined in sections of the sediment at 1 mm resolution down to 5 mm and then at 10 mm resolution to 50 mm depth and these distributions analysed using a sorption-diffusion-degradation model. The fine resolution in the depth profile permitted the detection of a maximum in the concentration of the compounds in the pore water near the surface, whereas concentrations in the sediment increased to a maximum at the surface itself. Experimental distribution coefficients determined from the pore water and sediment concentrations indicated a gradient with depth that was partly explained by an increase in organic matter content and specific surface area of the solids near the interface. The modelling showed that degradation of lindane within the sediment was necessary to explain the concentration profiles, with the optimum agreement between the measured and theoretical profiles obtained with differential degradation in the oxic and anoxic zones. The compounds penetrated to a depth of 40-50 rum over a period of 42 days. (C) 2004 Society of Chemical Industry.

Development of a sequential injection chromatography (SIC) method for determination of simazine, atrazine, and propazine

This paper describes the development of a sequential injection chromatography (SIC) procedure for separation and quantification of the herbicides simazine, atrazine, and propazine exploring the low backpressure of a 2.5 cm long monolithic C(18) column. The separation of the three compounds was achieved in less than 90 s with resolution > 1.5 using a mobile phase composed by ACN/1.25 mmol/L acetate buffer (pH 4.5) at the volumetric ratio of 35:65 and flow rate of 40 mu L/s. Detection was made at 223 nm using a flow cell with 40 mm of optical path length. The LOD was 10 mu g/L for the three triazines and the quantification limits were of 30 mu g/L for simazine and propazine and 40 mu g/L for atrazine. The sampling frequency is 27 samples per hour, consuming 1.1 mL of ACN per analysis. The proposed methodology was applied to spiked water samples and no statistically significant differences were observed in comparison to a conventional HPLC-UV method. The major metabolites of atrazine and other herbicides did not interfere in the analysis, being eluted from the column either together with the unretained peak, or at retention times well-resolved from the studied compounds.

Understanding the Effect of Adsorption Geometry over Substrate Selectivity in the Surface-Enhanced Raman Scattering Spectra of Simazine and Atrazine

This paper studies the selectivity of Well-defined Au and Ag nanostructures as substrates for the SERS, (surface-enhanced Raman scattering) detection of simazine (6-chloro-N,N`-diethyl-1,3,5-triazine-2,4-diamine) and atrazine (6-chloro-N-ethyl-N`-isopropyl-1,3,5-triazine-2,4-diamine). Our data showed that simazine and atrazine displayed similar SERS spectra when the Au was employed as substrate. Conversely, distinct SERS signatures were obtained upon the utilization of Ag substrates. Density functional theory (DFT) calculations and vibrational assignments suggested that, while simazine and atrazine adsorbed on Au via the N3 position of the triazine ring, simazine adsorbed on Ag via N3 and atrazine via N5. The results presented herein demonstrated that the adsorption geometry of analyte molecules can play a central role over substrate selectivity in SERS, which is particularly important in applications involving ultrasensitive analysis of mixtures containing structurally similar molecules.

Solid Lipid Nanoparticles Co-loaded with Simazine and Atrazine: Preparation, Characterization, and Evaluation of Herbicidal Activity

Funda����o de Amparo �� Pesquisa do Estado de S��o Paulo (FAPESP)

Monitoriza����o de pesticidas em ��guas de Esposende

De forma a proteger o ambiente e a sa��de humana, �� imperativo evitar, prevenir ou reduzir as concentra����es prejudiciais de poluentes nocivos na ��gua subterr��nea. A necessidade da obten����o de n��veis de protec����o da ��gua subterr��nea, encontra-se estabelecida em normas de qualidade e devem ser desenvolvidas metodologias que permitam a avalia����o do estado qu��mico da ��gua subterr��nea. Este trabalho experimental centrou-se no desenvolvimento de uma metodologia anal��tica de detec����o e quantifica����o por cromatografia gasosa com detector de captura de electr��es dos pesticidas atrazina e respectivos metabolitos (desetilatrazina e deisopropilatrazina), simazina, terbutilazina e o metabolito desetiterbutilazina, folpete, dimetoato, diazin��o, malati��o, cloropirifos e o azinfos-metilo em ��guas de po��os. O estudo progressivo baseou-se na colheita de ��gua a 20 po��os agr��colas na zona de Esposende, ��rea considerada pelo Minist��rio da Agricultura do Desenvolvimento Rural e Pescas como sendo uma zona vulner��vel. O m��todo utilizado para a valida����o da t��cnica cromatogr��fica baseou-se na norma ISO 8466-1:1990. Os par��metros de valida����o considerados foram: especificidade/selectividade, capacidade de identifica����o, limites de detec����o e quantifica����o, rela����o sinal/ru��do, linearidade e curva de calibra����o, precis��o (repetibilidade, precis��o interm��dia e reprodutibilidade), efici��ncia de extrac����o e arrastamento. O m��todo demonstrou ser capaz de identificar e quantificar os analitos, sem interfer��ncia de outros compostos. Obteve-se um valor para os par��metros da precis��o inferior a 10%, enquanto os mais baixos limites de detec����o e de quantifica����o foram, respectivamente, 0,014 e 0,047 ��g L-1. Na prepara����o de amostras optou-se pelo m��todo de extrac����o em fase s��lida, tendo sido testadas cinco diferentes tipos de colunas extractivas; Lichrolut�� EN/RP-18; Strata SDB-L e C18-E; Chromabond HR-P e HR-X, sendo que as colunas Lichrolut�� EN/RP- 18 apresentaram melhores resultados para a globalidade dos pesticidas. Da an��lise efectuada aos 20 po��os agr��colas verificou-se que apenas 3 n��o apresentavam qualquer vest��gio dos pesticidas monitorizados, sendo que as restantes apresentavam valores entre 0,05 e 53,2 ��g L-1, valores superiores aos impostos pela legisla����o em vigor (Decreto-Lei n.�� 208/2008 de 28 de Outubro para ��gua subterr��nea e Decreto-Lei n��306/2007 referente a ��gua para consumo). Verificou-se que os propriet��rios dos po��os agr��colas, dos quais se procedeu �� amostragem de ��gua para an��lise n��o t��m a consci��ncia da falta de qualidade dessa ��gua, nem dos malef��cios que possam advir do seu consumo.

Monitoriza����o de desreguladores end��crinos em ��guas

Da crescente necessidade de alimentos e da necessidade de travar a destrui����o de culturas por animais e insectos foram sintetizados os pesticidas. Por entre uma vasta gama de pesticidas alguns s��o desreguladores end��crinos o que se traduz num perigo para a sa��de humana pois pode despoletar altera����es nos seres vivos mesmo em concentra����es muito baixas. Devido a diversos factores nomeadamente a lixivia����o, ventos e outros agentes ambientais assim como a presen��a de terrenos agr��colas junto a diversos rios, estes encontram-se contaminados com pesticidas desreguladores end��crinos. O objectivo deste trabalho foi avaliar quais os pesticidas desreguladores end��crinos presentes nas ��guas de rios da regi��o Norte. Neste trabalho utilizou-se a t��cnica de microextrac����o em fase s��lida recorrendo a uma fibra de PDMS (100 ��m). Para tal as condi����es de optimiza����o foram testadas nomeadamente a quantidade de NaCl, quantidade de metanol, temperatura do injector e tempo de exposi����o. Os par��metros obtidos ��ptimos foram 0 % de NaCl, tempo de exposi����o de 45 min, temperatura do injector de 260 ��C e 2,5 % de metanol. Conseguiu-se a separa����o de todos os pesticidas desreguladores end��crinos com a seguinte programa����o temperaturas: inicio a 60��C por um minuto seguido de um aumento de 20 ��C/min at�� aos 200 ��C onde permanece por um minuto e de seguida um aumento de 5 ��C/min at�� aos 245 ��C onde permanece por 40 min. Fizeram-se curvas de calibra����o entre 0,01 ��g/L e 10 ��g/L. Constatou-se no entanto uma falta de reprodutibilidade entre as injec����es utilizando esta t��cnica. Os rios analisados foram o Rio Douro, Rio T��mega, Ria de Aveiro, Rio Lima, Rio Minho, Rio Sousa, Rio ��gueda, Rio C��vado e Rio Le��a. No Rio T��mega foram encontrados os seguintes pesticidas: diazin��o, ��-HCH, ��-HCH, ��-HCH, lindano, HCB, simazina/ atrazina, vinclozolina, alacloro, 2,4-D, malati��o, aldrina, bifentrina, metoxicloro e fenvalerato. No rio Douro est��o presentes HCB, simazina/ atrazina, vinclozolina, 2,4-D, malati��o, aldrina, fenvalerato e deltametrina. No rio Lima encontra-se diazin��o, ��-HCH, ��-HCH, 2,4-D, HCB, vinclozolina, lindano, simazina/atrazina, alacloro, malati��o, aldrina, fenvalerato e deltametrina. No rio Sousa os pesticidas encontrados foram: diazin��o, HCB, aldrina, ��-HCH, ��-HCH, ��-HCH, lindano, simazina/ atrazina, 2,4-D, cipermetrina, alacloro, fenvalerato e malati��o. No rio C��vado est��o presentes o diazin��o, ��-HCH, ��-HCH, ��-HCH, lindano, HCB, 2,4-D, malati��o, metoxicloro, cipermetrina e o fenvalerato. Na ria de Aveiro encontrou-se o diazin��o, ��-HCH, ��-HCH, ��-HCH, lindano, HCB, simazina/atrazina, 2,4-D, Malati��o e aldrina. No rio ��gueda est��o presentes o diazin��o, HCB, 2,4-D, aldrina e malati��o. E por ��ltimo no rio Le��a esta presente o diazin��o, 2,4-D, alacloro, malati��o, aldrina, cipermetrina e fenvalerato. A import��ncia deste trabalho reside na demonstra����o da presen��a destes pesticidas, desreguladores end��crinos nas ��guas superficiais da regi��o Norte.

Diagn��stico espa��o-temporal da ocorr��ncia de herbicidas nas ��guas superficiais e sedimentos do Rio Corumbata�� e principais afluentes

Residues of herbicides from sugarcane were monitored in waters and sediments of Corumbata�� River and tributaries. Ametryne, atrazine, simazine, hexazinone, glyphosate, and clomazone were detected in water samples, with negligible levels of ametryne and glyphosate in sediment samples. The area of recharge of the Guarani aquifer presented the highest triazine and clomazone levels. The triazines were detected at higher levels, with atrazine above Brazil's potability and quality standards. Total herbicide levels at some sampling points were 13 times higher than the European Community potability limit. There is no Brazilian standard for ametryne, although the risk is larger due to ametryne's higher toxicity for the aquatic biota.

Investigation of the occurrence of pesticide residues in rural wells and surface water following application to tobacco

In this work the exposure of wells and surface water to pesticides, commonly used for tobacco cropping, was assessed. Water consumption wells and surface water flows were sampled at different times. After a preconcentration step with solid phase extraction (SPE), the selected pesticides were determined by gas chromatography with electron capture detection (GC-ECD) or high performance liquid chromatography with diode array detection (HPLC-DAD). No pesticides were detected in the well water samples and surface water flow in the winter season. However, in the spring and summer higher concentrations of chlorpyrifos and imidacloprid were found in the water source samples. Atrazine, simazine and clomazone were also found. The occurrence of pesticides in collected water samples was related with the application to tobacco.

Metodologias eletroanal��ticas para a determina����o de herbicidas triaz��nicos por voltametria de onda quadrada e t��cnicas de deconvolu����o

This work describes the development of electroanalytical methodologies for the determination of atrazine, ametrine and simazine by square wave voltammetry on a mercury electrode. For pure atrazine and pure ametrine, the detection limits (DL) were 3.7 and 4.3 ��g L-1, respectively, while they increased to 4.8 and 6.5 ��g L-1 in the presence of 3.0 x 10-6 mol L-1 of the other component (a mathematical deconvolution program was used in the mixture cases). The voltammetric response for simazine could not be separated from that of atrazine and measurements were carried out only in pure simazine solutions (DL: 7.5 ��g L-1).

Estudo de sor����o de herbicidas pelos argilominerais vermiculita e montmorilonita

The clay minerals montmorillonite (MT) and vermiculite (VT), previously treated with Ca2+, K+ and Na+, were employed in a sorption study with herbicides. The herbicides 2,4-D, diuron, alachlor and metolachlor showed no interaction with MT and VT. On the other hand, the triazines presented a good sorption process, close to 100% for ametrine removal and near to 56 and 69% for atrazine and simazine, respectively, by MT. These results suggest that the MT specie may be a good material for triazines removal from aqueous medium and an alternative phase to preconcentration process, besides to exhibit a good selectivity.

Occurrence of agrochemicals in surface waters of shallow soils and steep slopes cropped to tobacco

Tobacco cultivation in shallow soils and steep landscape under intense use of agrochemicals contributes to environment degradation. In this study, we assessed the concentration of agrochemicals in draw wells used for human consumption and a creek in a small catchment predominantly cropped to tobacco. Chlorpyrifos, flumetralin, and iprodione were determined by gas chromatography with electron capture detection, while imidalcloprid, atrazine, simazine, and clomazone were quantified by high-performance liquid chromatography with UV detection. Considering all sampling sites, all agrochemicals were detected at least once, except for flumetralin. The occurrence of agrochemicals in tobacco crops is a consequence of their fast transfer to surface water.