Contents
| AIR HYGIENE REPORT no. 10 | |
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Contents |
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Lichens are recognised monitors of heavy metal deposition (Chapter II, Section 2). The same properties have assisted in their use of biomonitors of organic compounds.
The lichen, Usnea barbata was used to assess the chlorinated hydrocarbon burden at two sites on the mountains facing the Mediterranean Sea, near Monaco (Villeneuve et al., 1988). Results were comparable with chlorinated hydrocarbon values observed in industrial areas in Italy and Norway. Concentrations of insecticides and toxaphene were higher at the site of highest altitude and were thought to have been transported from agricultural areas to this exposed site. PCBs were unaffected by altitude which enabled bioconcentrations factors between lichen PCB content and the atmosphere to be calculated.
Muir et al. (1993) analysed samples of the lichen, Cladina rangiferina at a number of locations over a three-year period in Ontario, Canada. Concentration gradients were observed for DDT, chlordane and dieldren, with significantly higher concentrations in lichens in south-central Ontario locations than in northern and north-western locations. Multivariate statistical analyses, such as principal components analysis was applied to the data to examine dominant patterns of all individual organochlorine components, their variation with geographical location and establish relationships between lichen and air precipitation data. Data was insufficient to infer any conclusions regarding temporal trends.References
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