IMPACTS OF MINING ON THE ENVIRONMENT IN FINLAND

Acid mine drainage (AMD) is remaining one of the most serious, unresolved environmental problems deteriorating the quality of surface and ground waters. The acid is generated by the oxidation of iron-rich sulfides with a consequent lowering of pH and further dissolution of toxic metals from water-permeable tailings, waste rock piles and open pits. The problem is widespread in Finland, where during the past centuries nearly one hundred sulfide ores have been in active use. Most of the mines have been closed without remediation activities, and only little is known about their potential or present impact on environment.

We have studied and collected observations from seven closed and three active sulfide ore mines in order to analyze their impact to environment. On the basis of the observations it can be concluded that all sulfide mining affects the environment. Some of the studied closed mine sites are still causing severe deteriorating of the environment in form of metal load prohibiting fish and algae growth. It was also noted that mines impact on the environment in unpredicted and largely unknown ways. For example a former zinc-copper mine is polluting the environment due to cadmium leachates, and a former gold-copper ore causes arsenic pollution of surface waters.

The recent proposal for a directive of the EU parliament on the management of mining waste (com 2003 319) seeks to minimize the environmental risks arising from the extracting and treatment of sulfide ores. According to proposal there is an urgent need to inventor closed sulfide mines and their waste facilities. This is a major challenge for environmental geoscientists in our country. On the basis of our observations, a combination of hydrogeochemical and paleolimnological studies often gives the necessary information to understand the rehabilitation needs.