Lichens and mosses as monitors of industrial activity associated with uranium mining in northern Ontario, Canada—Part 1: Field procedures, chemical analysis and interspecies comparisons

A modified X-ray flourescence spectrometry technique allowed the detection of uranium in cryptogams with a detection limit of 0·5 to 1 μg U g−1 of plant material. The levels of five elements (Ti, Fe, Ni, Pb and U) in 109 lichen and 98 moss samples collected around two uranium mining communities in northeastern Ontario, Canada, are reported. Similar metal accumulation tendencies were observed for the pair of lichens, Cladonia rangiferina and C. mitis, and for the moss pair, Pleurozium schreberi and Dicranum spp. This interchangeabiligy combined with favourable availability, made the above species the most useful biological monitors. Interelemental content comparisons employing Pearson's linear correlation statistic indicated a strong positive association among the pairs iron/titanium, and uranium/ lead. Somewhat weaker positive correlations were observed in the individual comparisons of uranium levels with iron, or titanium, or nickel content. The associations between elements in mosses and lichens were in excellent agreement with the grouping based on the composition of the local uranium ores and tailings.