AQUIFER INTERCONNECTIVITY AND THE EFFECTS OF MINING ACID DRAINAGE ON THE QUALITY OF THE WATERS OF THE SANTA CATARINA CARBONIFEROUS BASIN

Abstract

Carboniferous activity in southern Santa Catarina State has been developed over a century and the lack of environmental management in mining projects caused significant changes in the water resources of the Araranguá Watershed. In addition to changes in water quality, collapses in underground mines caused the fracturing of overlying layers allowing the expansion of aquifer systems and surface waters interaction processes. In order to better understand these processes, samples of 9 wells from Rio Bonito Aquifer System, 4 wells from Alluvial Fan Aquifer System and 6 from surface waters of the same catchments were analyzed. Hydrochemical analysis indicates a predominance of calcium and sodium bicarbonate waters which in contact with acid mine drainage are transformed into sulfated waters. The isotopic composition of the samples shows similarity to the isotopic composition of meteoric waters, contributing to the hypothesis of the strong interaction between groundwater, waters from water table and surface waters, which occurs due to the brittle tectonics affecting gondwanic lithologies, and is intensified by the presence of underground mines.

Keywords: Hydrochemistry, Stable isotopes, Groundwater, Acid mine drainage.