Can a successional crop system associated with preemergent herbicides be a tool to control weeds?

The objective of this research was to evaluate weed control in a successional soybean-sorghum system by using preemergent herbicides. Two trials were conducted in soybean and two in sorghum, in different soil types (sandy in Rio Verde city and clayey in Montividiu city). All trials were established in a completely randomized block design with five preemergent herbicides in soybean (rates in): diclosulam 35.3 g a.i.·ha­1, chlorimuron 20 g a.i.·ha­1, sulfentrazone 200 g a.i.·ha­1, flumioxazin 50 g a.i.·ha­1, S-metolachlor 1728 g a.i.·ha­1, and two controls (hand weeded and untreated). Treatments in sorghum trials were the same to the soybean plus atrazine 1250 g a.i.·ha­1 and atrazine 1250 g a.i.·ha­1 + S-metolachlor 1728 g a.i.·ha­1. All treatments had four replicates. Weed control was assessed at 7, 14, 21 and 28 days after planting (DAP) in both crops. In addition, yield was measured when grains reached physiological maturity. All preemergent herbicide treatments successfully controlled weeds, specially Commelina benghalensis, Cenchrus echinatus and Eleusine indica, in both soybean trials until 28 DAP. In some weeds of sorghum, sulfentrazone, diclosulam and chlorimuron sprayed at soybean preemergence performed better than atrazine sprayed at sorghum preemergence. All preemergent herbicides sprayed at soybean preemergence did not affect soybean and sorghum yield, showing similarity with the hand weeded treatment. The results of this research provide evidence that the mix of crop succession and preemergent herbicide applications can be a strong strategy for integrated weed management.

Does doses and time of 2, 4-D application interfere in the physiology and wheat grains yield components?

The identification of the application stage and correct dose of 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide is important so that wheat is not harmed. In view of this, the objective of this study was to evaluate the effect of 2,4-D doses applied at different development stages of wheat crop. The experiment was conducted in a randomized block design, arranged in a 4 × 5 factorial scheme, with four replications. In factor A, the application stages (before tillering, tillering, first node and booting) were allocated and the doses of 2,4-D (0, 349, 698, 1047 and 1396 g.ha­1) were allocated in factor B. The variables evaluated were phytotoxicity at 7, 14, 21, 28 and 35 days after application of the treatments (DAT), photosynthetic activity, CO2 internal concentration, stomatal conductance, efficient water use and carboxylation efficiency. The number of spikes·m­2, spike length and number of full and sterile grains were determined in the preharvest. Thousand grain mass, grain yield and hectoliter weight were determined after harvest. The results demonstrate that the herbicide caused phytotoxicity to wheat, being greater in increasing doses and mainly before tillering, causing grain sterility and decreased productivity. The other yield components did not present difference when increasing the dose and application in different stages as well as the physiological variables. The increase of the 2,4-D doses applied before tillering and in the booting stage caused linear decrease in wheat grain yield.

Agronomic characterization of sunflower cultivars for animal feeding in tropical conditions

This study was developed to examine morpho-agronomic traits of 18 sunflower cultivars and identify superior cultivars in terms of grain yield, forage quality, or both, for animal feeding. Twenty-two morpho-agronomic traits related to plant development and architecture; earliness of maturity; grain yield (achenes); dry matter yield; and dry matter content were evaluated. Cultivars Hélio 253, Hélio 358, Embrapa 122, BRS 321, and Hélio 360 showed inflorescence at the final stage. Aguará 4 showed the lowest flowering rate, characterizing it as late-maturing. For grain yield, cultivars Charrua, Olisun 3, BRS 321, Paraíso 103CL, Paraíso 65, Aguará 6, and CF 101 are recommended, as they showed the highest achene yields (average: 1,541.67 to 2,148.81 kg.ha−1, respectively). Cultivars Charrua, Hélio 251, Olisun 3, Hélio 360, Paraíso 55, and Paraíso 103CL exhibited higher dry matter yields (9,550.93 to 11,789.91 kg ha−1) and were thus indicated for forage production. Cultivars Charrua, Olisun 3, BRS 321, Paraíso 103CL, Paraíso 65, Aguará 6, and CF 101 are recommended for grain yield, for the diet of monogastric animals; Charrua, Hélio 251, Olisun 3, Hélio 360, Paraíso 55, and Paraíso 103CL for forage yield, for ruminant feeding; and Charrua, Olisun 3, and Paraíso 103CL for both purposes.

Arsenic exposure in northern Mexican women / Exposición a arsénico en mujeres del norte de México

Abstract: Objective: To describe interindividual metabolism variations and sociodemographic characteristics associated to urinary arsenic, and to estimate the arsenic contamination in water from urinary total arsenic (TAs). Materials and methods: Women (n=1 028) from northern Mexico were interviewed about their sociodemographic characteristics and their urinary concentrations of arsenic species were measured by liquid chromatography. Inorganic arsenic (iAs) in water was estimated from urinary TAs. Results: Women were 20-88 years old. TAs in urine ranged from p10=3.41 to p90=56.93 μg/L; 74% of women had levels >6.4 μg/L. iAs in water varied from p10=3.04 to p90=202.12 μg/L; 65% of women had concentrations >10 μg/L, and 41%, concentrations >25 μg/L. Large variations in iAs metabolism were observed. TAs was significantly negatively associated with age and schooling, and positively with the state of residence. Conclusion: Exposure to iAs is an environmental problem in Mexico. Individual variations in metabolism are a challenge to design prevention and control programs.

Resumen: Objetivo: Describir las variaciones interindividuales del metabolismo y las características sociodemográficas asociadas con el arsénico urinario, así como estimar su contaminación en el agua. Material y métodos. Se entrevistó a 1 028 mujeres del norte de México; por cromatografía de líquidos se midieron los metabolitos urinarios de arsénico y, a partir de ellos, se estimó la concentración en agua. Resultados: Las mujeres tuvieron 20-88 años. El arsénico urinario varió de p10=3.41 a p90=56.93 μg/L; 74% de las mujeres tuvieron niveles >6.4 μg/L. El arsénico en agua varió de p10=3.04 a p90=202.12 μg/L; 65% de las mujeres tenían concentraciones >10 μg/L, y 41%, >25 μg/L. Se observaron amplias variaciones en el metabolismo del arsénico. El arsénico urinario se asoció negativamente con la edad y escolaridad, y positivamente con el estado de residencia. Conclusión: La exposición a arsénico es un problema ambiental en México. Las variaciones individuales en su metabolismo son un desafío para diseñar programas de prevención y control.

To be or not to be a carcinogen; delving into the glyphosate classification controversy

The International Agency for Research on Cancer (IARC) placed the most widely used herbicide glyphosate (GLY) into the category 2A (probably carcinogenic to humans), a classification questioned by experts from academia and industry. This article critically appraised the epidemiological and experimental data that led the IARC working group (WG) to consider GLY a probable human carcinogen and the ensuing controversy. An association of GLY with non-Hodgkin lymphoma was suggested by some observational studies. A non-causal explanation for this weak association, however, cannot be excluded. Contrary to WG's view, long-term rodent assays yielded no convincing evidence that GLY is carcinogenic. The mechanistic evidence remains elusive as well. Bacterial reverse mutation tests (including tester strains sensitive to oxidative mutagens) were clearly negative, and so were rodent genotoxicity assays by oral route. Tests with mammalian cells in vitro yielded conflicting results at high (cytotoxic) concentrations of GLY-based formulations. Conflicting results were also obtained when high doses of GLY-based herbicides were administered to rodents by the intraperitoneal route. Such high doses are unlikely to be attained in realistic scenarios of exposure. Finally, the IARC classification is based on a conjectural hazard, and rational public health interventions must be based on estimated risks.

Efeito protetor da melatonina sobre intoxicações por herbicidas / Protective effect of melatonin on poisoning by herbicides

O uso inadequado de herbicidas pode resultar em intoxicações agudas e, às vezes, crônicas por exposição em longo prazo a baixos níveis desses agentes tóxicos, podendo o herbicida atuar também como agentes teratogênicos, mutagênicos, cancerígenos e desreguladores endócrinos, com o aparecimento de doenças neurodegenerativas e distúrbios reprodutivos. Estudos têm revelado que a melatonina tem propriedades antioxidantes, anti-inflamatórias e imunomoduladoras e atua na reprodução. Essa indolamina está entre os agentes que têm se mostrado benéfico em intoxicações por herbicidas, porém não há relatos do uso de melatonina contra intoxicações por Glifosato-Roundup®, muito menos em associação com o Paraquat. Dessa forma, o maior interesse no tratamento das intoxicações por herbicidas, tem-se concentrado em medidas que impeçam ou minimizem as lesões celulares provocadas nos diversos sistemas biológicos. Assim, a melatonina, como antioxidante conhecido, pode ser mais uma alternativa contra as intoxicações por herbicidas associados e/ou individuais.

The inadequate use of herbicides may cause serious and sometimes chronic poisoning due to long exposure to low levels of toxic agents. Herbicides may also be teratogenic, mutagenic, cancerigenous agents and endocrine disruptors, with the occurrence of neurodegenerative diseases and reproduction disorders. Several studies have shown that melatonin has antioxidant, anti-inflammatory and immune-modulating qualities, besides affecting the reproduction system. It is among the agents which are beneficent in poisoning by herbicides even though no reports are extant on the use of melatonin against poisoning by Glyphosate-Roundup® alone or associated with Paraquat. Solutions that prevent or minimize cell lesions caused by several biological systems have been focused upon in the treatment for poisoning with herbicides. Thus, melatonin, a known antioxidant, may be an alternative against the poisoning by single or associated herbicides.

Efeito do herbicida glifosato sobre o crescimento e produção de metabólitos secundários em Microcystis aeruginosa e Cylindrospermopsis raciborskii / The effect of herbicide glyphosate on the growth and of secondary metabolites production in Microcystis aeruginosa and Cylindrospermopsis raciborskii

ianobactérias, conhecidas por sua habilidade de sintetizar metabólitos com ação tóxica, podem se tornar dominantes em águas com altas concentrações de nitrogênio e fósforo. Embora a toxicidade do glifosato, o herbicida mais usado no mundo, em alguns organismos aquáticos seja conhecida, poucos estudos abordam o efeito desse composto sobre a produção de metabólitos secundários por cianobactérias. O objetivo deste trabalho foi avaliar a influência de diferentes concentrações de glifosato (produto técnico) sobre o crescimento e produção de cianotoxinas e microgininas pelas cepas brasileiras Microcystis aeruginosa LTPNA 08 e Cylindrospermopsis raciborskii CENA 302. Na presença de 15 mg/L de glifosato, o crescimento e a produção de toxinas pela M. aeruginosa foram reduzidos e de microgininas significativamente aumentada. Já a C. raciborskii, quando exposta à 20 mg/L de glifosato teve seu crescimento e síntese de clorofila-a, carotenoides e saxitoxinas aumentados. Concentrações superiores a 20 e 30 mg/L impediram o crescimento celular das cepas LTPNA 08 e CENA 302, respectivamente. A análise de ácidos graxos mostrou perfis bastante distintos entre as cepas. Na cepa LTPNA 08, enquanto que na presença de 10 mg/L de glifosato ocorreu diminuição do teor do ácido linoleico, o ácido estearidônico foi aumentado. Nenhuma das concentrações testadas promoveu alteração sobre o perfil de ácidos graxos da cepa CENA 302. A toxicidade de 5 produtos formulados a base de glifosato foi comparada ao produto técnico em ambas as linhagens-teste. Observou-se uma resistência distinta entre as cepas e toxicidade também variável entre as formulações comerciais. Sendo assim, diante da elevada resistência das cianobactérias M. aeruginosa e C. raciborskii ao glifosato, e considerando-se a elevada interferência antrópica através das práticas agrícolas, pode-se inferir que o uso excessivo e frequente desse herbicida é capaz de estimular o crescimento e dominância desses organismos, podendo modificar a estrutura e funcionalidade de ecossistemas aquáticos

Cyanobacteria, known for their ability to synthesize toxic metabolites, can become dominant in water bodies with high concentrations of nitrogen and phosphorus. Although the toxicity of glyphosate, the most widely used herbicide in the world, in some aquatic organisms is well known, few studies address the effect of this compound on the production of secondary metabolites by cyanobacteria. The aim of this study was to evaluate the influence of different concentrations the herbicide glyphosate (technical grade) on growth and production of cyanotoxins and microginins by Brazilian strains of Microcystis aeruginosa LTPNA 08 and Cylindrospermopsis raciborskii CENA 302. In the presence of 15 mg/L of glyphosate, growth and toxin production by M. aeruginosa were reduced and microginins cell quota significantly increased. The C. raciborskii strain, when exposed to 20 mg/L of glyphosate, had the growth, and chlorophyll-a, carotenoids and saxitoxins production increased. Concentrations above 20 and 30 mg/L prevented cell growth of LTPNA 08 and CENA 302 strains, respectively. Fatty acid analysis showed distinct profiles among the strains. When exposed to 10 mg/L of glyphosate, a decrease in the linoleic acid and increase in stearidonic acid content were observed in M. aeruginosa LTPNA 08 strain. None of the tested concentrations of glyphosate promoted change on the fatty acid profile of CENA 302 strain. The toxicity of 5 glyphosate formulated products was compared to technical product to both strains. There was a distinct resistance among strains and also a variable toxicity among formulated products. Thus, given the high glyphosate resistance of M. aeruginosa and C. raciborskii cyanobacteria, and considering the high anthropogenic interference through agri cultural practices, it can be inferred that excessive and frequent use of this herbicide is able to stimulate growth and dominance of these organisms, which may modify the structure and function of aquatic ecosystems

Eficácia do glyphosate e 2, 4-d no controle de Commelina villosa / Efficacy of glyphosate and 2, 4-D in control of Commelina villosa

O objetivo do presente trabalho foi avaliar a eficácia de glyphosate e 2,4-D, isolados e em mistura, no controle de Commelina villosa. Foram estudadas duas metodologias de avaliação de absorção de herbicidas em oito intervalos de tempo para a lavagem (simulando chuva após a aplicação) e corte (simulando abortamento, como estratégia de defesa) das folhas: 2, 4, 6, 8, 12, 24 e 48 horas após a aplicação dos herbicidas, além de um tratamento sem lavagem ou corte das folhas, em delineamento experimental inteiramente casualizado com quatro repetições, dispostos em um esquema fatorial 3 x 7 + 1 (três herbicidas x sete períodos – horas após a aplicação). Os herbicidas e doses testados foram: glyphosate (1.440 g ha-1), 2,4-D (720 g ha-1) e a mistura glyphosate + 2,4-D (1.080 + 720 g ha-1). A simulação de chuva interferiu de forma negativa no controle das plantas com o herbicida glyphosate. O controle com o herbicida 2,4-D foi influenciado apenas no período de 2 horas. Os períodos de simulação de chuva não influenciaram no controle das plantas com a mistura de glyphosate + 2,4-D. Para o estudo com corte das folhas tratadas, todos os tratamentos independente do período para corte das folhas foram influenciados de forma negativa no controle, sendo que as plantas apresentaram rebrotas quando tratadas com o herbicida 2,4-D isolado.

Efficacy of glyphosate and 2,4-d in the control of Commelina Villosa. The aim of this study was to evaluate the efficacy of glyphosate and 2,4-D alone and in combination, in the control of Commelina villosa. We studied two methodologies for evaluating herbicide absorption in eight time intervals for washing (simulating rainfall after application) and cutting of leaves (simulating abortion as a defense strategy): 2, 4, 6, 8, 12, 24 and 48 hours after herbicide application, and a treatment without washing or cutting the leaves in a completely randomized design with four replications in a 3 x 7 + 1 factorial design (three herbicides x seven periods – hours after application). Herbicides and doses tested were: glyphosate (1,440 g ha-1), 2,4-D (720 g ha-1) and a mixture of glyphosate + 2,4-D (1,080 + 720 g ha-1). The simulation of rain interfered negatively in the plant control with glyphosate. The control with the herbicide 2,4-D was affected only for the period of 2 hours. Periods of rain simulation did not influence the control of plants with a mixture of glyphosate + 2,4-D. For the study with the cutting of treated leaves, all treatments regardless of the period of cutting the leaves were influenced negatively in terms of plant control, the plants showing regrowth when treated with 2,4-D alone.

Toxicidad en peces de herbicidas formulados con glifosato / Toxicity in fishes of herbicides formulated with glyphosate

En nuestro país existe una gran extensión de hectáreas cultivadas con soja transgénica, la misma ha sido modificada genéticamente para soportar la acción de un herbicida denominado glifosato. Debido a la gran cantidad de formulaciones comerciales que incluyen glifosato es de importancia analizar el impacto ambiental producido por éstas. La evaluacion de la toxicidad aguda de dos herbicidas comerciales formulados con glifosato y de una solución del mismo; frente a peces de la especie Poecilia reticulata "lebistes" acusa que una de las soluciones produce mortalidad del 100 % de los especimenes a 100 μl/l (equivalente a 48 mg/l de principio activo); la otra a 50 μl/l (equivalente a 24 mg/l de principio activo) y la solución formulada con glifosato puro no produce mortalidad aún a concentraciones de 400 mg/l. Utilizando dosis sub letales en función de los datos obtenidos en el ensayo de toxicidad aguda se determinó que a largo plazo especimenes de Cyprinus carpio haematopterus "carpa koi", manifestaron severas alteraciones hematológicas principalmente frente a una de las formulaciones evaluadas.

Nowadays, transgenic soya, modified in order to withstand the impact of the herbicide glyphosate, in one of the main crops grown in Argentina. Due to the large number of commercial formulations that include this drug, is important to analyze both, the acute and chronic environmental impact that they cause. Here the acute toxicity of two commercial herbicides glyphosatebased toward the fish Poecilia reticulate "guppy" was evaluated and compared with pure glyphosate solutions. Interestingly, while commercial herbicides formulations induce a 100% of mortality at concentration ranged between 50 and 100 μl/l, the pure glyphosathe does not present mortality even at doses higher than 400 mg/l. When some long term effects toward Cyprinus carpio haematopterus "koi" were determined by using the sub-lethal doses already calculated it was demonstrated that one of the commercial herbicides induces severe haematological alterations.

Efeito de diferentes herbicidas, doses e volume de calda na dessecação de milheto [Pennisetum Glaucum (L. Leek)] / Effect of different herbicides, doses and spray volume in the chemical management of pearl millet [Pennisetum Glaucum (L. Leek)]

Objetivou-se nesse trabalho avaliar a eficácia de diferentes herbicidas aplicados em pósemergência na de secação do milheto com diferentes doses e volumes de calda de aplicação. Para a dessecação do milheto foram utilizadas doses de 0, 25, 50 e 100% dos herbicidas glyphosate (1.440 g ha-1), em três formulações comerciais (Round up Original, Round up Transorb e Round up WG), paraquat + diuron (500 + 250 g ha-1) e amônio-glufosinato (800 g ha-1). Em todos os tratamentos foram utilizados dois volumes de aplicação (200 e 400 L ha-1). Manteve-se uma testemunha sem aplicação de herbicidas. Os efeitos dos tratamentos foram avaliados visualmente aos 3, 7, 14, 21 e 28 dias após aplicação. Ao final das avaliações foi determinada a massa seca das plantas. O estudo de campo foi instalado no delineamento em blocos casualizados. No final do estudo, aos 28 DAA, todos os tratamentos apresentaram controle total das plantas de milheto, independente da dose e do volume de aplicação, exceto para os tratamentos com paraquat + diuron e amônio-glufosinate na menor dose (25% da dose), nos dois volumes de aplicação, que apresentaram ainda controles considerados bons a muito bom, sendo que para esses dois herbicidas houve efeito do volume de calda, na qual o controle foi superior com o uso de volume menor.

The objective of this work was to evaluate the efficacy of different herbicides applied in post-emergence in the desiccation of pearl millet with different doses and spray volumes. For the desiccation, doses at 0, 25, 50 and 100% of the herbicide glyphosate (1,440 g ha-1) were used in 3 formulations (Original Round up, Round up Transorb and Round up WG), paraquat + diuron (500 + 250 g ha-1) and glufosinateammonium (800 g ha-1). In all treatments, 2 spray volumes (200 and 400 l ha-1) were used, and there was 1 treatment (control) without the application of herbicides. The treatment effects were evaluated visually at 3, 7, 14, 21 and 28 days after application (DAA). At the end of the evaluations, the dry mass of the plants was determined. The field trial was carried out in randomized block design. At the end of the study, at 28 DAA, all treatments presented total control of plant pearl millet, regardless of the dose and spray volume, except the treatments with paraquat + diuron and glufosinate-ammonium at the lower dose (25%), in 2 spray volumes, which nevertheless showed good and very good control, these two herbicides presenting an effect of volume, in which the control was higher with the use of smaller volume.

Microbial degradation of sulfentrazone in a Brazilian rhodic hapludox soil

Sulfentrazone is amongst the most widely used herbicides for treating the main crops in the State of São Paulo, Brazil, but few studies are available on the biotransformation of this compound in Brazilian soils. Soil samples of Rhodic Hapludox soil were supplemented with sulfentrazone (0.7 µg active ingredient (a.i.) g-1 soil) and maintained at 27ºC. The soil moisture content was corrected to 30, 70 or 100 percent water holding capacity (WHC) and maintained constant until the end of the experimental period. Herbicide-free soil samples were used as controls. Another experiment was carried out using soil samples maintained at a constant moisture content of 70 percent WHC, supplemented or otherwise with the herbicide, and submitted to different temperatures of 15, 30 and 40º C. In both experiments, aliquots were removed after various incubation periods for the quantitative analysis of sulfentrazone residues by gas chromatography. Herbicide-degrading microorganisms were isolated and identified. After 120 days a significant effect on herbicide degradation was observed for the factor of temperature, degradation being higher at 30 and 40º C. A half-life of 91.6 days was estimated at 27º C and 70 percent WHC. The soil moisture content did not significantly affect sulfentrazone degradation and the microorganisms identified as potential sulfentrazone degraders were Nocardia brasiliensis and Penicillium sp. The present study enhanced the prospects for future studies on the bio-prospecting for microbial populations related to the degradation of sulfentrazone, and may also contribute to the development of strategies for the bioremediation of sulfentrazone-polluted soils.

Desenvolvimento de método simples para a determinação de resíduos de Diuron por cromatografia a líquido em amostras de laranja / Development of simple method for determination of Diuron residues by liquid chromatography in orange samples

Este artigo apresenta método simples para a extração e determinação de diuron em amostras de laranja (compreendendo casca e polpa). O método consistiu na extração do pesticida com acetona em agitador mecânico. O extrato foi filtrado em Celite e particionado com n-hexano. Evaporou-se a fase hexânica sob N2, sendo o resíduo solubilizado em metanol. A análise foi realizada por Cromatografia a Líquido de Alta Eficiência (CLAE) com detecção por Ultra-Violeta (UV) em 230nm. Obtiveram-se recuperações médias entre 109 e 110 por cento para amostras fortificadas nos níveis 0,1 e 0,5 mg Kg-1. Os Limites DE qUANTIFICAÇÃO (lq) e de Detecção (ld) foram 0,1 mg Kg-1 e 0,004mg Kg-1, respectivamente. As amostras analisadas não apresentaram resíduos de diuron nas condições experimentais estudadas

Effects of herbicide on the kidneys of two Venezuelan cultured fish: Caquetaia kraussii and Colossoma macropomum (Pisces:Ciclidae and Characeae)

The use of chemical pesticides and herbicides has increased environmental pollution and affected ichthyofauna in the watersheds where they are used.We studied the effect of an herbicide, triazine, on the kidneys of two species (Caquetaia kraussii and Colossoma macropomum )widely found in Caribbean and South American rivers.In Venezuela,these species are abundant and have a high aquaculture potential because they may be cultured and reproduced in captivity.Four kidney samples from juveniles of each species exposed to the herbicide were examined by Transmission Electron Microscopy.Kidney tubule alterations included loss of plasmalemma and cell interdigitations, misshaped mitochondria,decrease in rough endoplasmic reticulum and free polysomes,and the presence of autophagic vacuoles and primary lysosomes.These alterations at the cellular level may explain fish behaviour in terms of kidney tubule pathology,and relative amounts and conditions of organelles within affected cells

Determinaçäo de resíduos de 2,4D em amostras vegetais / Residues determination of 2,4D in vegetables sample

Adaptou-se metodologia existente para determinaçao de resíduos do herbicida 2,4D (ácido 2,4 diclorofenoxiacético) em matrizes vegetais. A metodologia proposta foi testada em amostras de cana-de-açúcar, arroz, milho, soja e trigo. O 2,4D foi extraído com diclorometano em meio ácido e derivatizado com pentafluorbenzil brometo. Os derivados foram submetidos ao cleanup em mini colunas de florisil, para entao serem quantificados por cromatografia gasosa com detetor de captura de elétrons. A recuperaçao apresentou-se na faixa de 76-94 por cento.

Metodologia para análise de herbicidas clorofenoxiacéticos e clorofenóis em amostras de água de rio

Como consequência do desenvolvimento da mecanização na agricultura, tem sido observado um aumento acentuado no uso de herbicida em relação aos outros pesticidas (Jordan & Cudney, 1987). Na região norte do Estado do Rio de Janeiro, em virtude das extensas culturas de cana-de-açúcar, existe uma aplicação significativa de herbicidas, sendo que as formulações contendo herbicidas clorofenoxiacéticos ou derivados das triazinas, são as mais utilizadas. Os herbicidas clorofenoxiacéticos são também de amplo uso em pastagens e no plantio de grãos, sob a forma de sais ou de ésteres. No meio ambiente, estes ésteres são rapidamente hidrolisados e em seguida, degradados, podendo formar compostos intermediários, como clorofenóis, causadores de alterações na qualidade da água, mesmo que em baixas concentrações. Apesar de existirem inúmeros métodos para análise destes herbicidas no meio aquoso, pouco tem sido relatado sobre a análise concomitante de herbicidas clorofenoxiacéticos e correspondentes clorofenóis resultantes da degradação. O presente trabalho tem por objetivo desenvolver uma metodologia alternativa para a análise de herbicidas clorofenoxiacéticos e clorofenóis em amostras de água de rios, empregando extração e preconcentração através de uma resina, de forma a reduzir custos e tempo de análise

An increasing growth on the use of herbicides more than other pesticides has been observed, due to the development of mechanized agriculture (Jordan & Cudney, 1987). In the northern region of Rio de Janeiro, due to the wide spread sugar-cane culture, a significant use of herbicides can be observed, though the more utilized are the ones containing chlorophenoxiacetic acids and triazines derivatives. Chlorophenoxiacetic herbicides are algo extensively used in pastures j and in the grains plantation, as salt or esters. Once in the environment, these esters are quickly hydrolysed and then degraded, which may form interrnediate .. compounds, such as chlorophenols, causing alterations in the quality of water, even when present in low concentrations. Although there are several methods for the analysis of these herbicides in aqueous media, just a few reparts have been found on the simultaneous analysis of chloraphenoxy hebicides and degradation products such as chlorophenols. " The aim of this work is the development of an altemative methodology to the simultaneous analysis af chloraphenaxy herbicides and chlorophenols in fresh water samples, using a resin for extraction and precancentratian, in arder to reduce costs and save time for the analysis

Gas chromatographic peak enhancement problem and solution

The peak enhancement of Bentazon [3-isopropyl-1 H-2,1,3-benzothiazin-4 [3H]-one-2,2-dioxide]; the active ingredient of Basagam herbicide; and its metabolites in fortified samples have been studied using capillary gas chromatography [GC] with a thermionic specific detector [TSD], flame photometric detector [FPD] and mass selective detector. [MSD]. The enhancement problem which was connected with the infection of samples and standards in methanol was eliminated by using non-polar solvent for GC infection