Caracterização Isotópica Do Aqüífero São Sebastião Na Região Do Pólo Petroquímico De Camaçari – Ba

The groundwater reservoirs from the São Sebastião<br>Formation in the region of Camaçari – Dias D´Ávila<br>are intensively exploited through deep well pumping<br>for industrial and urban uses. The geometry of the<br>reservoirs is defined by sandstones blocks<br>interlayered by shale-siltstone sequences in a geologic<br>context separated by faults. The exit temperature of<br>the water of the production wells allowed to identify<br>the capture zone of water that varied from the<br>superficial part of the aquifer to more than 300 m of<br>depth. The isotopíc composition of the groundwater<br>was found very homogeneous and close to the<br>average composition of precipitation in the nearby<br>region of Salvador, indicating a local recharge of<br>these aquifers without participation of transported<br>water from long distance by a regional flow system in<br>the deep layers. The difference between the isotopic<br>composition of surface water (rivers and dams) and<br>monitoring wells with the groundwater indicated no<br>direct connection between these water bodies.