Spatial dispersal of airborne pollutants and their effects on growth and viability of lichen transplants along a rural highway in Norway

Abstract

AbstractThis study aims to quantify dispersal of airborne traffic-related elemental pollutants and concurring responses – relative growth rate (RGR), maximal quantum yield of PSII (Fv/Fm), and chlorophylls (Chlab) – in four epiphytic lichens (Lobaria pulmonaria,Parmelia sulcata,Ramalina farinacea,Usnea dasopoga). Lichens were transplanted from 25 September to 26 March to 1·5 m tall stands in open farmlands at 10, 15, 30, 50 and 100 m from the E6 highway (SE Norway), along three transects on each side usnea dasopoga of the road. The concentrations of most elements (Ca, Mg,Na,Fe,Al, Zn,Ba,Cu,V,Cr,Ni,Co,Sn, As, Mo) significantly increased with increasing proximity to the road. Elements inboldhad elevated concentrations relative to controls, at least in some species at 100 m. The heavy metal accumulation increased from foliose to fruticose lichens in the order:P. sulcata>L. pulmonaria>R. farinacea≫U. dasopoga.However,L. pulmonariawas the only species with strong pollutant-dependent reductions in growth,Fv/Fm, Chlab, and Chla/b-ratio. The RGR and viability parameters were adversely affected by the roadside environment near the road only (≤15 m), and only after substantial heavy metal accumulation. Measurement of metal accumulation in lichens is thus a far more sensitive way of monitoring road pollutants than recording growth and lichen viability. Despite strong species-specific contrasts in elemental concentrations, most road pollutant elements responded similarly to distance from the road in all species.