ENVIRONMENTAL IMPACT OF CLOSING MINING ACTIVITIES - A CASE STUDY FROM BALAN, ROMANIA

Mining activities have played an important role in the development of human communities and in the economic growth of societies. However, in many cases, the exploitation of the resources was carried out in an unsustainable manner and contamination of the environment or ecological accidents occurred, which lately led to increased financial efforts for the remediation of contaminated sites. The negative effect on the environment of the entire technological process of exploration, exploitation and preparation of ores is continued with the impact of closing the mines. The aim of this paper is to study the environmental impact of the Balan mining industry, Romania, on the receptors, before and after closing. In the Balan area the mines were closed in 2004, but the restoration of the mining area began only in 2011, so, meanwhile the population and the environmental system were affected. A tailing pond was created in the southern area of the mining perimeter, where all the residues from the flotation of the ore were pumped. During the period in which the plant was running, the material in the tailing pond was humid and had the consistency of mud. Since the mine was closed, though, and no fresh material was added, the water started to evaporate and, especially during summer, the finest particles from the tailing pond are easily carried away by wind, ending up in people's yards and gardens. For this study, soil samples were collected from the area of the tailing pond, both in 2004, when the mine was closed, and in 2011, when the remediation began. Total heavy metals in soil were analyzed by X-ray fluorescence spectrometry and pseudo-total metals were extracted using aqua regia assisted by microwave procedure and the concentrations were determined by atomic absorption spectrometry. The results showed that, because of the large period of time between ending of the mining activities and beginning of the restoration, heavy metals accumulated in the soil around the tailing pond, due to atmospheric deposition of particles containing trace metals from the pond.