SUMMARYThe most efficient of five methods used for the extraction of ATP from lichens was found to be the use of Tris4-EDTA after acetone treatment. Changes in the concentration of ATP in transplanted Ramalina duriaei (De Not.) Bagl. reflected the influence of air pollution on this lichen. The ATP concentration remained constant at a control station in a rural site, whilst at urban stations it decreased to 10% of the control value. Changes in the concentration of ATP were compared with chlorophyll degradation, as expressed by the ratio OD 435 nm/OD 415 nm. The values of this ratio also decreased in the urban sites, but less so than the ATP.

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