Establishment of geochemical background values of parameters related to coal contamination

The city of Criciúma was impacted by decades of coal mining exploration and tailings disposal. These activities directly interfere with natural resource systems, causing the contamination of ground and surface water resources through acid mine drainage (DAM).The definition of geochemical background values is a strategy to quantify and qualify the impact of mining activities on natural resources. The present paper aimed to establish geochemical background values in groundwater from springs distributed in the city of Criciúma/SC. The water quality data were evaluated using the Exploratory Data Analysis (EDA) and cumulative frequency representation methods. Thus, the work allowed to determine the background values for the analytical parameters pH, Iron, Manganese and Sulphate, when it was confirmed that values for pH found within the range of 5.5 to 7.9 can be considered normal for the groundwater. Iron and manganese had background concentrations of 2.58 and 0.30 mg / L respectively, while sulfate had concentrations between 2.0 and 20.0 mg / L. The background in many cases can of course supplant legally regulated limits, a fact observed in this study for manganese, which has a background concentration three times higher than that recommended by MS Ordinance n. 5/2017 which deals with water potability.