Tellam, John H., Rivett, Michael O., Israfilov, Rauf G., Herringshaw, Liam G., Chambel, Antonio, Duque, Jorge, and Manuel Madeira, M.
This investigation of urban groundwater problems in the city of Évora is one of the first in Portugal, its main objective being to develop a hydrochemical knowledge of the city's groundwater. Thirteen water points, represented by 7 large diameter wells and 6 deep wells, were selected for sampling. The major ions were analysed, as well as temperature, EC, pH and total hardness. The results show that most of the waters are HCO3-Mg-Ca-Na type, but some of the samples are Cl in type and one is clearly Cl-Na in type. The EC varies between 230 and 2500 μS/cm. The nitrate content varies between 0.5 and 310 mg/L, but over 50 % of the samples exceed the 25 mg/L maximum recommended by Portuguese Law. The absolute permitted maximum of 50 mg/L is also exceeded in 30 % of the samples. When compared with water quality elsewhere in Alentejo, the results are clearly high in terms of EC, nitrates and chlorides. The high content of nitrates and chlorides may be an indication of urban contamination. [ABSTRACT FROM AUTHOR]