Updated: May 24, 2022
As a part of the Lichen_ART project, founded by the Arts Council Ireland I had a chance to monitor the air quality in the Vale of Clara Nature reserve for nitrogen dioxide (NO2) and sulphur dioxide (SO2), using diffusion tubes.
The source of NO2 is mostly fuel combustion coming from industry and vehicles. With sunlight and volatile organic compounds it is involved in the ground-level ozone formation, which causes damage to plants and is harmful to human health.
The SO2 pollution can also come from domestic boilers and fires, metal extraction and natural fires. The pollution with SO2 significantly impacts reducing crop yields and is involved in acid rain formation.
The experiment was a month-long (October 2021) monitoring of both gases using diffusion tubes. The results revealed low pollution levels for both gases. The average NO2 pollution for the Nature Reserve was at 2.04 ug/m3 (micrograms per cubic metre of air), and for SO2, 1.1 ug/m3.
The results align with the environmental observation of the nitrogen and sulphur sensitive lichen species. Lichens are symbiotic organisms that consist of the thallus of a fungus and a photosynthetic alga. Because of their specific structure and sensitivity to pollution, some species can be bioindicators of air quality.
The Usnea sp., greenish-grey, beard lichen (called Old Man's Beard), often attached to tree bark or branches, is an example of the species occurring only in the clean air areas.
A similar environmental condition for proper growth has another species, Evernia prunastri - Oakmoss. This interesting lichen, not only is a bioindicator of clean air, but thanks to it's pronounced scent, it is harvested for production of perfumes. In some European countries the lichen is now critically endangered species.
These two species are ubiquitous across the Vale of Clara Nature Reserve, which, thanks to the vast amount of vegetation, can purify any amount of pollution, giving the sensitive lichens space to grow and flourish.
For more information on lichens as bioindicators, please view the video that was prepared for an online workshop with primary and secondary schools for the Lichen_ART project.