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Within the Ecuadorian native vegetation, weeds have been the plant that at any given time can compete for water, nutrients, light, space and carbon dioxide (CO2) with a crop, affecting productivity in quantity. and quality. Thus, this research aims to analyze the efficiency of two chemical herbicides for weed control in banana crops and thus determine the effect caused by both Ametrine and Ammonium Glufosinate. Based on the analysis of results, through the combined use of the herbicides Ametrine and Glufosinate ammonium, a higher percentage of effectiveness was observed in the control of weeds in the plantain crop (Musa × paradisiaca). Compared to the other treatments applied, this strategy is relevant since it guarantees good growth and essential development of the crop. [ABSTRACT FROM AUTHOR]

O crescimento da demanda global por alimentos juntamente com as exigências do mercado - não só relacionados à qualidade, mas também à diversidade - estão levando ao aumento do uso de agrotóxicos nas lavouras. Nesse contexto, a busca de informações e tecnologias para reduzir riscos ambientais associados ao uso de pesticidas tem papel importante. Estudos de laboratório têm fornecido indicações sobre o comportamento de pesticidas em solos, porém indicações sobre a identidade e a toxidez dos metabólitos formados são raras. O presente estudo avaliou o comportamento da ametrina em solos brasileiros, e a identidade e quantidade de dois metabólitos principais foram determinadas. Maior quantidade de radioatividade foi detectada nos extratos dos solos, indicando que a formação de resíduos ligados ocorreu apenas em pouca extensão, o que pode representar risco ambiental. Valores de DT50 foram menores nos solos com mais matéria orgânica.

Neste trabalho avaliou-se o fungo Fusarium oxysporum como potencial bioindicador de contaminação de herbicida da classe das triazinas, por meio do monitoramento do crescimento fúngico. Para tanto, foi avaliado o crescimento micelial em meio de cultura extrato malte e ágar na presença do herbicida ametrina, em diversas concentrações. O crescimento micelial foi avaliado pela determinação do teor de ergosterol, por CLAE/DAD, em comprimento de onda de 281 nm. A quantificação do ergosterol passa pelas etapas de extração em etanol, saponificação em base forte, fracionamento em hexano:água (4:1) e análise por CLAE. O crescimento do fungo foi retardado pelo aumento da concentração do herbicida, mostrando que o potencial dessa técnica de avaliação de contaminação por ametrina. O ergosterol mostrou ser um bom indicador de biomassa fúngica metabólicamente ativa.In this work the fungi Fusarium oxysporum was evaluated as bioindicator of contamination by a triazine class herbicide, through the screening of the fungal growth. For so, micelial growth measurement was done in culture medium of malt extract and agar in the presence of different concentrations of the herbicide ametrine. The micelial growth measurement was done by the ergosterol content. The ergosterol content was determined by HPLC/DAD, in the wavelength 282 nm, after sample extraction and pre-treatment. The results showed good correlation among fungal biomass and ergosterol content. The fungi growth was reduced by the increase of the ametrine concentration. This shows that using that fungi may be a good alternative for contamination screening.

Solar heterogeneous photocatalysis is an advanced oxidation technology, which allows a successful treatment of many recalcitrant and emergent pollutants, such as: pesticides, industrial dyes and pharmaceutical compounds. Nonetheless, despite its effectiveness, the costs of applying this process are high when it is necessary to achieve a complete mineralization or to obtain an environment-friendly effluent. Photocatalytic-biological coupled systems have become in a feasible alternative able to treat efficiently these pollutants. In this work, a coupled system consistent of two compound parabolic collectors (CPC) solar photoreactors and a subsurface flow constructed wetland (SFCW) at pilot-scale was tested for degrading a mixture of commercial pesticides used in sugar cane crops. For measuring the process performance, regarding to the pollutant removal, the increase of the BOD5/COD ratio and the total organic carbon (TOC) removal were estimated for each separated system and the coupled system. Three different levels of solar UV accumulated energy and feed flow-rates to the SFCW were considered for the experimental design. The pilot-scale coupled system increased the BOD5/COD ratio from 0.15 to 0.90, and the TOC removal (total mineralization) was around 80%. [ABSTRACT FROM AUTHOR]

In this work, the adsorption and reuse capability of TiO2 were studied. The photocatalytic degradation of a commercial pesticide mixture consisting of Karmex®, Profiamina®, Igram®, and the coadjuvants Cosmoaguas® and Inex-A®, was evaluated. As experimental setup, a set of batch reactors and UV artificial light were used. The reduction of total organic carbon (TOC) was measured to evaluate the mineralization capability of the photocatalytic process. The optimal conditions were found by using a response surface experimental design. Three consecutive catalyst reuses were made with no special rinse treatment. The catalyst lost its capability to adsorb and degrade the pollutant mixture after three reuses because of the desorption of the intermediate species produced during the photocatalytic process. [ABSTRACT FROM AUTHOR]

A degradabilidade do herbicida ametrina foi determinada em solo Areia Quartzosa com e sem adição de folhas secas de cana-de-açúcar, cultivada em campo, tratada ou não tratada com herbicida ametrina e em solo esterilizado. Amostras de 10g de solo com umidade ajustada à 70% da capacidade de campo e tratadas com 1ml de 14C-ametrina, na concentração de 8mg/ml e atividade específica de 800Bq/mg, foram distribuídas em frascos com tampa e incubadas em ambiente escuro, a 23oC, por 63 dias. Comparando a mineralização da ametrina em solo sem adição e com adição de folhas de cana-de-açúcar tratada ou não tratadas, observou-se 12 a 13 vezes mais 14CO2 desprendido em solos com a adição de palha. Nestes tratamentos foi observado, após 63 dias de incubação, maior número de microrgarnismos, maior atividade microbiana e formação de maior número de metabólitos, quando comparados com os tratamentos sem adição de palha ou o esterilizado. Os resultados sugerem que a degradação da ametrina é de origem microbiológica e ocorre por cometabolismo.The degradation rate of the herbicide ametryn in a sandy soil was evaluated comparing the amendment of sugar cane straw cultivated with or without ametryn treatment, with non-amended soil, and sterilized soil control. Samples of 10g of soil were placed in flasks, treated with 1ml of 14C-ametryn (8mg/ml and 800Bq/mg), and were tightly closed and incubated in the dark at 23oC for 63 days. Every week the CO2 traps were changed and soil water content ajusted to 70% of soil field capacity. The mineralization rate of ametryn was 12 and 13 times higher with soil amendement of treated leaves and non-treated leaves, respectivily as compared to non amended soil. The leaf amendement led to a greater number of microrganism colonies, higher microbial activity and more ametryn metabolites than non-amended or sterilized soil. The results suggest that ametryn degrades mainy through microbial co-metabolism.