Investigation of Sterile Mining Dumps Resulting from Ore Exploitation and Processing in Maramures County, Romania

Abandoned sterile dumps can be a significant source of environmental pollution, therefore the distribution of trace elements throughout mining is vital. Monitoring environmental factors in closed mining perimeters aims to track the quality of discharged waters in the emissary and assess acid mine drainage, the quality of the soil and vegetation, stability, and the condition of the land surfaces within the perimeter of the sterile deposits. One of the primary sources of land, water and air pollution is sterile mining dumps. Knowing the source of pollution is the first step in adequately managing the affected areas. This paper investigates the physical–chemical properties and the concentrations of heavy metals in sterile dumps resulting from mining. We studied one sterile dump that was the result of ore processing and whose surface was covered with abandoned mixed ore concentrate (Pb, Zn), located in the Băiuț mining area (Romania), and a second sterile mining dump that was the result of exploration and exploitation work in the Ilba mining area (Romania). In order to determine the physicochemical characteristics of the studied sterile dumps and to determine the concentration of heavy metals, 27 sterile samples and one soil sample were taken from the Băiuț dump. Additionally, 10 sterile samples and one soil sample were collected from the Ilba dump. Aqua regia extractable concentrations of heavy metals were determined by inductively coupled plasma optical emission spectrometry. At the same time, using a portable XRF, we analyzed selected samples from each site for total metal concentrations. Furthermore, from each site, one sample was analyzed by FT–IR spectrometry. The pH values in both sterile dumps were highly acidic (≤3.5) and the content of heavy metals was generally increased.