TITLE:
Sensitivity of Lichens to Diesel Exhaust under Laboratory Conditions
AUTHORS:
Ulrike Langmann, Pierre Madl, Roman Türk, Werner Hofmann, Georg Brunauer
KEYWORDS:
Lichens, Biomonitors, Diesel Exhaust, Photosynthetic Yield, Gas Exchange
JOURNAL NAME:
Journal of Environmental Protection,
Vol.5 No.13,
October
29,
2014
ABSTRACT: Lichen vegetation reacts very sensitively to a variety of air pollutants
including increased nitrogen concentrations as well as to traffic exhaust in
general, which makes lichens reliable monitoring organisms for atmospheric
pollution. Recent environmental studies have shown that decreasing abundance of
acidophytic lichen species and the increase of nitrophytic lichens can be
explained by elevated levels of atmospheric nitric-compounds adsorbed onto nanoparticles. One major source of these atmospheric compounds amongst a wider pollution
inventory is diesel
exhaust—a mixture of gases and particle matter. This study
aimed to shed light on the impact of diesel exhaust on the viability of six
differently sensitive lichen species. Diesel exhaust particle concentrations
in the laboratory experiments resembled those at a local highway during rush
hour. By incubation in a closed stainless steel chamber we could exclude
influences from other pollutants than diesel exhaust providing explicit data
about the effects of diesel exhaust on lichens. The investigations revealed
effects on the photosynthesis of the lichen photobionts and hence the lichen
vitality. The conclusions of this study are that 1) the photobiont is affected
stronger as the mycobiont and 2) older parts of the lichen are damaged first.
Another remarkable result of this study is that 3) these lichens are
regenerating to some extent during incubation-free periods—unless the organism is not damaged too much to
restore photosynthetic activity. To our knowledge this is the first study
evaluating the impact of diesel exhaust on lichens under laboratory conditions
separate from other interfering pollutants.