Environmental impact of coal mining on the natural environment in Poland

Saline waters occurring in underground coal mines in Poland often contain natural radioactive isotopes, mainly 226Ra from uranium series and 228Ra from thorium series. Approximately 40% of total amount of radium remains underground in a form of radioactive deposits, but 225 MBq of 226Ra and 400 MBq of 228Ra are released daily to the rivers with mine effluents. Technical measures as spontaneous precipitation of radium in gobs, decreasing of amounts of water inflows into underground working etc. have been undertaken in several coal mines and as the result total amount of radium released to the surface waters diminished of about 60% during last 5-6 years. Mine waters can cause a severe impact on the natural environment, mainly due to its salinity. But also the enhancement of radium concentration in river waters, bottom sediments and vegetation is observed. Sometimes radium concentration in rivers exceeds 0.7 kBq/m3, which is due to Polish law a permissible level for waste waters. The extended investigations were performed in all coal mines and on this basis the radium balance in effluents has been calculated. Measurements done in the vicinity of mine water's settling ponds and in rivers gave us an opportunity to survey radium behaviour in river waters and the range of contamination. Solid waste materials with enhanced natural radioactivity have been produced in huge amounts in power and coal industries in Poland. There are two main sources of these waste products. As a result of combustion of coal in power plants low radioactive waste materials are produced, with 226Ra concentration seldom exceeding few hundreds of Bq/kg. Different situation is observed in coal mines, where as a result of precipitation of radium from radium-bearing waters radioactive deposits are formed. Sometimes natural radioactivity of such materials is very high, in case of scaling from coal mines radium concentration may reach 400 000 Bq/kg - similar activity as for 3% uranium ore. Therefore maintenance of solid waste with technologically enhanced natural radioactivity (TENR) is also a very important subject. (author)