Metals in Calluna vulgaris, Empetrum nigrum, Festuca vivipara and Thymus praecox ssp. arcticus in the geothermal areas of Iceland

This investigation was conducted to identify the content of metals inCalluna vulgaris(familyEricaceae),Empetrum nigrum(familyEricaceae),Festuca vivipara(familyPoaceae) andThymus praecoxsubsp.arcticus(familyLamiaceae), as well as in the soils where they were growing in eight geothermal heathlands in Iceland. Investigation into the vegetation of geothermal areas is crucial and may contribute to their proper protection in the future and bring more understanding under what conditions the plants respond to an ecologically more extreme situation. Plants from geothermally active sites were enriched with metals as compared to the same species from non-geothermal control sites (at an average from about 150 m from geothermal activity). The enriched metals consisted of Cd, Co, Cu, Fe and Ni inC. vulgaris; Cd, Mn and Ti inE. nigrum; Hg and Pb inF. vivipara; and Cd, Fe and Hg inT. praecox. Notably,C. vulgaris,E. nigrum,F. viviparaandT. praecoxhad remarkably high concentrations of Ti at levels typical of toxicity thresholds. Cd and Pb (except forC. vulgarisandF. vivipara) were not accumulated in the shoots of geothermal plants.C. vulgarisfrom geothermal and control sites was characterised by the highest bioaccumulation factor (BF) of Ti and Mn;E. nigrumandF. viviparaby the highest BF of Ti and Cr; andT. praecoxby the highest BF of Ti and Zn compared to the other elements. In comparison with the other examined species,F. viviparafrom geothermal sites had the highest concentration of Ti in above-ground parts at any concentration of plant-available Ti in soil.