Relationship between fluoride contents and loss of lichens near an aluminium works

The relationship between F contents and damage to previously unpolluted saxicolous lichens (Ramalina sp) was examined in the vicinity of an Al works on the island of Anglesey, North Wales. Damage was greatest <2 km from the works, where 41% of Ramalina thalli showed >50% chlorosis and necrosis. Loss of lichens (measured by changes in percent cover in 58 permanent quadrats) decreased with increasing distance from the works. Lichens well-exposed to emissions had the largest F content and 20 to 30% more losses than those less-exposed. Well-exposed lichens had rates of loss of cover of 4.9% km^?1 yr^?1, whereas more sheltered thalli had losses of 3.7% km^?1 yr^?1. In contrast, relatively uncontaminated lichens increased in % cover. Content of F reflected both distance from the works and exposure to emissions; losses, and F content, were closely related (r²=0.90). Lichens containing 300, 100 and 50 μg F g^?1 dry weight lost 46, 15 and 10% of cover yr^?1, respectively.