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1L - Exposure Modelling (WEP/88) Pesticide fate in mediterranean ditch. Rubio Muņoz, Ana 1, 2, Nicelli, Marco1, Capri, Ettore1, 1 Istituto di Chimica Agraria ed Ambientale. Universitā Cattolica del Sacro Cuore., Piacenza, PC, Italia2 Department of Agricultural, Geology and Pedology, University of Murcia, Spain., Murcia, MU, Spain ABSTRACT- Pesticides, commonly used in agriculture in order to improve yields, may affect the quality of soil, water and air. Pesticides are often found in surface waters, and as there are many interations between pesticides and sediments, in which pesticides may accumulate, the contamination of surface waters is of concern. In recent years useful computer simulation models, such as TOXSWA 1.2(Adriaanse P.,1999), have been developed for the purpose of estimating exposure concentrations in water courses adjacent to agricultural fields. In southern Europe, field ditches are frequently dry and also used for field irrigation. However, high concentrations of pesticides may accumulate or may be mitigation in ditch, both water and sediment. Is of concern because there aren't many experimental evidence where scenarios are differents. The objetive of this study is to obtain information on the environmental behaviour of three pesticides used as test( e-chlorpyrifos, m-chlorpyrifos, penconazole) and to compare the performance of the TOXSWA model with experimental results. Pesticides were sprayed together into an experimental ditch( depth 0.6 m, surface width 0.9 m)simulating the drift loading up the ditch. In two separate experiments, the pesticides were applied on a 20-metre length of a 40-metre ditch. The experimental ditch was initially dry to allow introduction of pesticides directly into the sediments, but an artificial water flow of 3 l/min was maintained afterwards throughout the experiments. In the first experiment, the pesticide was sprayed on dry sediment, in the second on the ditch water. Regular water samples were taken 10 m, 20 m and 38 m downflow from the injection point. Sampling continued for ten days after the sediment application and for seven days the ditch-water application experiment, and the pesticide concentrations in the water samples were determined with GC-MS. The obtained exposure concentration data was compared with respective TOXSWA simulation output. Key words: ditch, pesticide, mitigation, toxswa |
