Comparative study of mineral and surface waters of Araxa spa, Minas Gerais State, Brazil

摘要

The natural mineral waters of the springs Dona Beja (DBS) and Andrade Junior (AJS) from Araxa city, in the Brazilian State of Minas Gerais (MG), are well known since the nineteenth century when started the studies of their healing properties for the tuberculosis treatment. In Brazil, the period 1930-1950 corresponded to the construction peak of thermal and non-thermal spas for therapeutic and leisure purposes. In 1944, the President Getulio Vargas inaugurated a large spa at Barreiro area in Araxa city. The DBS waters have low salinity, high radioactivity, discharge sustained by the recharging rainwater, and expected low residence time in the aquifer due to the maximum recharge-discharge distance of 2-3 km. The AJS waters are hypothermal/thermal, alkaline, sulfured, highly saline, exhibiting deep circulation and discharging in a site dominated by slightly weathered rocks. Barreiro area is also characterized by the exploration of phosphate fertilizer (begun in 1947-1948) and niobium (identified in pyrochlore in 1953). Since the 60s and 70s, the demand for these resources increased, favoring the release of contaminants into the environment. As a consequence, several professionals and institutions belonging to different sectors of the society have pointed out potential environmental problems due to possible contamination of the DBS and AJS waters, with implications for reducing the tourism activities in the region that take an important role on the municipality economy. This study compared the major hydrochemical characteristics of the DBS and AJS waters with those of other surface waters and rainwater occurring in that area for identifying possible degradation of their quality due to the anthropogenic inputs taking place there.