Se determinó el comportamiento de carbarilo, carbofuran, metsulfuron metilo y bensufuron metilo en el sistema agua/sedimento. En el caso de carbarilo se determinó solamente la degradación de este insecticida en el agua, en equilibrio con el sedimento, mientras que se siguió la cinética de degradación de carbofuran tanto en agua como en la fase sólida del sistema. Se realizaron también experimentos de laboratorio y de campo para determinar la adsorción de carbofuran y las sulfonil ureas en el sedimento de los canales de drenaje. Fue notable la disipación de carbarilo en el agua, que no se detectó al cabo de 17 días. Tampoco se detectó el naftol, producto de la degradación de carbarilo. Debido a su solubilidad alta en el agua, el carbofuran se adsorbió en el sedimento, pero siempre mantuvo una concentración de equilibrio elevada en fase acuosa. La degradación fue muy rápida y similar en ambas fases. A los 21 días de iniciado el experimento no se detectaba en ellas el carbofuran. A escala de laboratorio la adsorción dinámica de carbofuran en el sistema agua/sedimento dependió fuertemente del flujo de la fase móvil, y fue máxima para el flujo menor investigado. En el caso de las sulfonil ureas investigadas, el flujo de agua no tuvo influencia tan marcada en la adsorción como en el carbofuran. Los experimentos similares a escala de campo en el CAI arrocero Los Palacios corroboraron los resultados de laboratorio. En ninguno se detectó la presencia de carbofuran en el punto de muestreo, situado a 1 000 m del origen del experimento. Los residuos de carbarilo fueron determinados por cromatografía de capa delgada. En el caso del carbofuran los residuos presentes en agua se determinaron por cromatografía gaseosa, mientras que los presentes en sedimentos se determinaron por HPLC, así como los análisis de sulfonilureas. | Behavior of carbaryl, carbofuran, metsulfuron methyl and bensufuron methyl was determined in the water/sediment system. In the case of carbaryl the degradation was determined only in water, in equilibrium with the sediment. The kinetics of carbofuran degradation was carrying out in both water and sediment. Laboratory and field experiments to determine the carbofuran and the sulfonyl ureas adsorption in the sediment of the drainage canal were carried out also. Carbaryl dissipation in water was notable. This pesticide was not detected after 17 days. Neither naphtol, product of the carbaryl degradation, was detected. Carbofuran was adsorbed in the sediment due to it high solubility in water. The carbofuran degradation was very rapid and similar in both phases, it was not detected after 21 days. Dynamic adsorption of carbofuran in water/sediment system in laboratory scale depended strongly on the mobile phase flow. The maximum dynamic adsorption was obtained with the smaller flow tested. Water flow in sulfonyl ureas had not notable influence in the adsorption as carbofuran but field scale realized in CAI Los Palacios, corroborated laboratory results. Carbofuran presence was not detected in a sampling point located 1000 m from the origin of the experiment. Carbaryl residues were determined by TLC. Carbofuran residues in water were determined by GC, while sediment residues were determined by HPLC just like sulfonyl ureas.

Se utilizó la extracción en fase sólida utilizando la resina XAD-2 para concentrar los plaguicidas presentes en muestras de agua. Se trabajó con plaguicidas que pueden constituir un riesgo de contaminación de las aguas, los niveles de residuos se determinaron usando un Cromatógrafo Gaseoso provisto de un detecctor NPD y por cromatografía de capa delgada, obteniéndose buenas recuperaciones y reproducibilidades. Demostrándose que es un método alternativo con el cual se logra un ahorro considerable de solventes. | Solid phase extraction usingSolid-phase extraction using XAD-2 resin to concentrate pesticides present in water samples was used. The work was done with pesticides, which can constitute a contamination risk for water. Residues level were determinate using gas chromatography with a NPD detector and for thin layer chromatography, to obtain good recovery and reproducibility. Was demonstrating to be an alternative method and permit considerable economy of solvent.

Mestrado em Engenharia Agronómica - Instituto Superior de Agronomia | This study aims to assess groundwater exposure to pesticides in agricultural ecosystems of potato and carrot of a hidrogeologycal vulnerable area of the aquifer system of the Tagus left margin, belong to the Palmela, Alcochete e Montijo councils. Besides a region characterisation under several aspects, a priori environmental exposure assessment of the registered pesticides to potato and carrot was assessed, on the basis of a selection of the physical-chemical properties and partition coefficients, and through multicompartimental models and leaching indexes. It was shown that several of these molecules have affinity to the water compartment and leaching potential. Pesticide residue analysis was performed by solid phase microextraction (SPME) followed of gas chromatography coupled to mass spectrometer (GC-MS) in 15 samples collected from five irrigation wells and in three dates. It was detected at least one pesticide in 53% of the analysed samples, namely pesticides metribuzin, α-endosulfan and β-endosulfan, with maximum concentration levels of 0,17; 3,92 and 1,53 µg/L, respectively. In this study it was shown the need for a careful selection of the pesticides to apply, taking into account their intrinsic characteristics and environmental conditions, towards a pesticide sustainable use.