Assessment of acid-base buffering properties of Flavoparmelia caperata: influence of age and pollution exposure

Abstract

This paper focuses on binding sites of lichens. The aim was to investigate the extracellular ionisable functional groups or binding sites that can play a (binding) ligand's role in young (peripheral) and older (central) thallus parts of the epiphytic lichens Flavoparmelia caperata collected under different pollution load environments. Potentiometric acid-base titration was used to obtain the capacity of lichens to retain extracellularly bound H+ and pKa distributions describing the acid-base properties of the lichen. Titration data were used to constrain the proton-exchange properties of surface functional groups. The results indicate that for F. caperata, neither ambient conditions nor specific lichen thallus parts affect capacity and pK values of ionisable groups.