Contamination of settling ponds and rivers as a result of discharge of radium-bearing waters from Polish coal mines

Saline waters from underground coal mines in Poland often contain natural r adioactive isotopes, mainly Ra-226 from the uranium decay series and Ra-228 from the thorium series. Approximately 40% of the total amount of radium r emains underground as radioactive deposits, but 225 MBq of Ra-226 and 400 M Bq of Ra-228, are released daily into the rivers along with the other mine effluents from all Polish coal mines. Technical measures such as inducing t he precipitation of radium in gobs, decreasing the amount of meteoric inflo w water into underground workings, etc, have been undertaken in several coa l mines, and as a result of these measures, the total amount of radium rele ased to the surface waters has diminished by about 60% during the last 5-6 years. Mine water can have a severe impact on the natural environment, main ly due to its salinity. However, associated high levels of radium concentra tion in river waters, bottom sediments and vegetation have also been observ ed. Sometimes radium concentrations in rivers exceed 0.7 kBq/m(3), which is the permitted level for waste waters under Polish law. The extensive inves tigations described here were carried out for all coal mines and on this ba sis the total radium balance in the effluents has been calculated. Measurem ents in the vicinity of mine settling ponds and in rivers have given us an opportunity to study radium behaviour in river waters and to assess the deg ree of contamination. Solid waste materials with enhanced natural radioacti vity have been produced in huge amounts in the power and coal industries in Poland. As a result of the combustion of coal in power plants, low-radioac tive waste materials are produced, with Ra-226 concentration seldom exceedi ng a few hundreds of Bq/kg. A different situation is observed in coal mines , where, as a result of precipitation of radium from radium-bearing waters, highly radioactive deposits are formed. Sometimes the radioactivity of suc h materials is extremely high; precipitates from coal mines may have radium concentrations of 400 000 Bq/kg - equivalent to 3% uranium ore. Usually, S uch deposition takes place underground, but sometimes co-precipitation of r adium with barium takes place on the surface, in settling ponds and in rive rs. Therefore management of solid waste with technorogically enhanced natur al radioactivity (TENR) is a very important subject. (C) 2001 Elsevier Scie nce Ltd. Al rights reserved.