Bioaccumulation capacity of two chemical varieties of the lichen Pseudevernia furfuracea

The concentrations of 18 trace elements (Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, Sr, V, and Zn) were measured in two varieties of the epiphytic lichen Pseudevernia furfuracea in order to compare their bioaccumulation capacity. Var. ceratea and var. furfuracea have identical morphology, substrate requirements and ecophysiology, but produce different secondary metabolites (lichen substances). Lichen substances may influence the processes of bioaccumulation of trace elements. We tested the hypothesis that the different metabolic chemical composition of the two varieties may influence the elements uptake. Lichen thalli were collected in a remote area of north-west Italy and transplanted, for one month in two seasons, to the urban-industrial area of Genoa (NW Italy). Lichen material was analysed by means of ICP-AES and bioaccumulation data were interpreted in terms of EC ratio (the ratio of each element after the exposure and, in control samples, prior to exposure). There were significant differences between the two varieties, which could be possibly related to their chemistry: var. ceratea has a higher accumulation capacity for all elements, except for Ca and Cu (which were lower in var. ceratea transplanted in Summer). Particularly, 10 out of 18 elements (Al, Cd, Co, Cr, Fe, Mg, Ni, Sr, and V) showed 'severe accumulation' in var. ceratea in both seasons. Thus, in order to enhance data quality in biomonitoring studies, it is suggested to avoid the joint use of the two varieties.