Groundwater quality in wells in central rural Finland: a microbiological and radiochemical survey

The microbiological, physicochemical, and radiochemical water quality from samples of 150 rural wells in Finland was analyzed. Organic matter exceeded 12 mg KMnO4 L(-1) in 63% and nitrate 25 mg NO3 L(-1) in 29% of the wells. NO3--concentrations were higher in wells with cattle. Fecal coliforms and fecal streptococci were found in 10-40%. There was no direct positive correlation between heterotrophic and indicator bacteria. Salmonella or Campylobacter were not detected. Human pathogen Listeria monocytogenes was isolated from two and Yersinia enterocolitica serotypes O5 or O6 from four waters not containing fecal coliforms. Thus, the predictive value of fecal coliforms to indicate these pathogens is poor. Coliphages were found in seven wells. Mean concentrations of radon and long-lived alpha-active radionuclides were lower and those of beta-emitting radionuclides higher than the mean concentrations measured from groundwater in Finland. Radionuclides from the Chernobyl fallout were not detected