Lichens experimental studies

Experimental studies of mineral weathering rates in the presence of oxalic acid demonstrate the importance of LPD. For example, in the presence of 1 mM oxalic acid, rates of silica elution from feldspar can increase up to 15-fold at circumneutral pH, while A1 elution rates can increase by two orders of magnitude (Barker et al, 1997). Similar results are reported for quartz and olivine (Grandstaff, 1986 Bennett et al, 1988), and indicate that oxalate leaching of aluminium, calcium, magnesium and other cations from primary silicate minerals can yield a silica-rich residue similar to that found in association with endolithic lichens (Johnston Vestal, 1993 Lee Parsons, 1999). 

Experimental studies quantifying LPD reaction equilibria and kinetics involving major rock-forming minerals and important lichen acids. 

Hill, D. J. (1971). Experimental study of the effect of sulphite on lichens with reference to atmospheric pollution. New Phytol. 70, 831-836. 

The sensibility of lichens to atmospheric pollution was demonstrated in the last two decades in various international and national publications. Recent studies showed that the survey of a large territory with lichens turns identification of atmospheric pollution sources possible (Sloof, 1993). The use of lichens is the only possibility to go through a large scale monitoring, which otherwise would be done with an enormous amount of air samplers and samples. Response of lichens to the environment is being studied through modelling very recently in our Institute (Reis et al., 1999). This is made with lichen transplants whose response to airborne particulate matter, and total deposition is followed experimentally. 

Woodwell and Gannutz (1967) extensively studied the resistance of lichens in the same experimental area as Brodo and under almost iden-... 

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