Caracterización y modelación del transporte preferencial de plaguicidas organofosforados en suelos productivos bajo riego. Aplicación al Distrito Colonia Centenario, Patagonia Argentina
[EN] In this thesis, transport and fate of organophosphate pesticides - azinphos-methyl and chlorpyrifos- in productive soils from the valley of the Neuquén River in the Patagonia Argentina are analysed. Climate of the region is arid, so traditional fruit production is under flood irrigation. The so...
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| Tipo de documento: | tese |
| Data de publicação: | 2016 |
| País: | España |
| Recursos: | Universitat Politècnica de València (UPV) |
| Repositório: | RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia |
| Idioma: | espanhol |
| OAI Identifier: | oai:riunet.upv.es:10251/62587 |
| Acesso em linha: | https://riunet.upv.es/handle/10251/62587 |
| Access Level: | Acceso aberto |
| Palavra-chave: | Flujo preferencial Plaguicidas, modelación, contaminación, Patagonia Argentina INGENIERIA HIDRAULICA TECNOLOGIA DEL MEDIO AMBIENTE |
| Resumo: | [EN] In this thesis, transport and fate of organophosphate pesticides - azinphos-methyl and chlorpyrifos- in productive soils from the valley of the Neuquén River in the Patagonia Argentina are analysed. Climate of the region is arid, so traditional fruit production is under flood irrigation. The soils in the floodplain are predominant Aridisols with textures from sandy loam to clay loam. Methodologically, the thesis was based on: field experiments and data and information processing conducted over a period of about 7 years. Dominant soil sites were selected in a transect perpendicular to the axis of the valley. In each place, pits were performed in order to describe horizons present in the profile. Samples were collected to determine textural composition and water retention curve in laboratory. Field experiments were done with the dye tracer FD & C Blue N° 1, applying water depth similar to those used in the production irrigation, to describe the mechanisms of preferential flow present in A and B horizons of soil. Through principal component analysis, the selected four sites were grouped in two types with different hydraulic and textural characteristics. Field studies and laboratory tests along with bibliographic information allowed the parametrization of the dual-permeability model MACRO. Calibration was done with groundwater level data and azinphos-methyl concentration data measured in the soil horizons, while validation was performed with chlorpyrifos determined in the same samples as azinphos-methyl. The modelling of the dynamics of azinphos-methyl and chlorpyrifos in the profiles of both types of soil corroborated the existence of preferential flow as a mechanism that occurs in short time intervals and facilitates the entry of pesticides into the soil. The preferential migration occurs mainly through biopores, structures that form soil aggregates and heterogeneities- such as boundaries between horizons- in both types of soil. In the clay loam soil, preferential migration is also produced through desiccation cracks. Boundary conditions, surface irrigation and water table swing at the base of the profile, link the dynamic of preferential transport. Pesticides transport through the soil micropores is performed with a slower flow, in balance, enabling retention and degradation of the solutes in the surface layers. Uncertainty in predicting pesticide leaching into the aquifer was analysed by sensitivity analysis of the 35 model parameters. In addition to the sensitivity of the model to the soil hydraulic and geochemical pesticides parameters, the irrigation depth is the main source of uncertainty in estimating both types of soil and substances. Productive management alternatives were simulated to reduce leaching into the underlying unconfined aquifer. Among these, the incorporation of organic matter was the best alternative. Finally, aware of the complexity of the phenomenon studied and its modelling, the most relevant aspects that would improve the application of MACRO to study the impact of pesticides leaching in the valley production systems are cited. The model parameterization for the types of soil present in the region facilitates the use of this tool both at the profile and basin scale. The implementation of the parameterized model with GIS will be able to classify the productive area in pollution sensitive areas of unconfined aquifer by the application of pesticides. |
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