info:eu-repo/semantics/article
FILTRAÇÃO DE MEMBRANA E A SALINIZAÇÃO DE ÁGUA SUBTERRÂNEA: APLICAÇÃO A AQUÍFEROS DAS BACIAS DO RECÔNCAVO E TUCANO
FILTRAÇÃO DE MEMBRANA E A SALINIZAÇÃO DE ÁGUA SUBTERRÂNEA: APLICAÇÃO A AQUÍFEROS DAS BACIAS DO RECÔNCAVO E TUCANO
Autor
LIMA, OLIVAR A. L. DE
Institución
Resumen
The Ilhas and São Sebastião aquifers in some regions of the Recôncavo and Tucano sedimentary basins contain water with high quantities of dissolved salts. Theoretical and experimental works have shown that shale layers may act as semi-permeable membranes that allow water to pass through them but restrict the passage of saline ions. This work presents a mathematical analysis of a hydrodinamic model idealized for those aquifer to evaluate the role of membrane filtration mechanisms as a factor influencing chemical changes during groundwater movement. The model consists of a sequence of three homogeneous and isotropic sandstone layers of uniform thicknesses intercalated with shale layers also considered homogeneous, isotropic and of uniform thicknesses. The sequence is bounded laterally on the dow-dip side by a impervious contour represented by a fault. Hydrostatic heads among the aquifers are assumed to increase linearly from the margins of each aquifer to the fault contour. The derived equations permit the analysis of salt concentrations in aquifers as a function of hidraulic and geometric parameters as well as of time. Despite the several restrictions, the theoretical concentrations estimated on the basis of this model show a good correspondence with the concentration estimated from electrical well logs for the São Sebastião aquifer. It is concluded that this mechanism may sactisfactorilly explain the observed water concentration in that aquifer. The Ilhas and São Sebastião aquifers in some regions of the Recôncavo and Tucano sedimentary basins contain water with high quantities of dissolved salts. Theoretical and experimental works have shown that shale layers may act as semi-permeable membranes that allow water to pass through them but restrict the passage of saline ions. This work presents a mathematical analysis of a hydrodinamic model idealized for those aquifer to evaluate the role of membrane filtration mechanisms as a factor influencing chemical changes during groundwater movement. The model consists of a sequence of three homogeneous and isotropic sandstone layers of uniform thicknesses intercalated with shale layers also considered homogeneous, isotropic and of uniform thicknesses. The sequence is bounded laterally on the dow-dip side by a impervious contour represented by a fault. Hydrostatic heads among the aquifers are assumed to increase linearly from the margins of each aquifer to the fault contour. The derived equations permit the analysis of salt concentrations in aquifers as a function of hidraulic and geometric parameters as well as of time. Despite the several restrictions, the theoretical concentrations estimated on the basis of this model show a good correspondence with the concentration estimated from electrical well logs for the São Sebastião aquifer. It is concluded that this mechanism may sactisfactorilly explain the observed water concentration in that aquifer.