Lichens are organisms with two live components: a tiny fungus
and a unicellular alga (or cyanobacteria). Such a symbiosis
is responsible for certain peculiarities used for monitoring
the air quality.
Effectively, lichens do not underact with the bearing substratum,
especially because they do not have roots and they are totally
dependent on the air for their nutrition. They have a continuous
growth, lack resistance in the hydric stress and cannot react
to the modifications of the Air Quality.
Therefore, all substances and particles contacting their surface
penetrate inside and are trapped by a network of fungi filaments.
According to these peculiarities,
two categories of techniques are used to perform environmental
Both techniques are based on field work
with natural biocaptors called lichens (mainly those lichens which
grow on tree bark :
1 - Flora studies (bioindication)
2 - Analysis (bioaccumulation or
The Aair Lichens Company accompanies his institutional
and industrial customers during the presentation of the results
to the representatives of the state and to the local elected members.
We participate in the reports of the studies during the Local Committees.
In optimal ecological conditions,
lichens live and reproduce with a state of balance and numerous
sorts constitute a lichenic community.
The variations of the composition
of the lichenic flora under the influence of the Air Quality
at the human level represent the base of the lichenic flora
studies. Indeed, the atmospheric pollutions lead a selection
of species, the most sensitive disappear while the resistant
stabilize or proliferate according to the nature of the concerned
pollutant. These peculiarities authorize the use of the inventory
of lichens species with the aim to represent the surfaces
where the Air Quality is modified or, on the contrary, excellent.
The geographic references allow
drawing up maps of modeling by connecting the results and
the geographic coordinates. It is then possible to spatialise
the Air Quality on maps. Sensitive or protected zones are
shown and the Air Quality can be follow by the lichenic flora
From initial studies, a selection
of representative plots allows to realize a biomonitoring.
(BIOACCUMULATION OR BIOKEEPING BACK)
The lichens physiology and constitution,
their absence of protection towards trace elements pollutants
make them able to accumulate or temporarily retain more than
50 trace-elements, heavy metals or organic molecules such
as Polycyclic Aromatic Hydrocarbons, pesticides, and dioxins
The use of lichens allows to spatialise
the fall-out of pollutants and their intensity. The taking
of populations of lichens, collected according to a rigorous
protocol on vertical supports is subjected after preparation
to dosages confided to guaranteed and approved laboratories.
We use these techniques
regularly for the industry, Local governments and the General
From initial studies, a
selection of representative sectors is used to realize an
annual or biennial biosurveillance.