Interspecies calibration of heavy-metal concentrations in nine mosses and lichens:-Applicability to deposition measurements

The study describes a method for including nine alternative moss and lichen species in heavy-metal air-pollution surveys based on concentrations in one of the species. Iron, Cu, Zn, Pb, Ni and Cd concentrations have been measured in Dicranum polysetum, Hylocomium splendens, Hypnum cupressiforme, Pleurozium schreberi, Pohlia nutans, Cladonia rangiferina, Hypogymnia physodes, Pseudevernia furfuracea and Usnea filipendula from 57 sites in coniferous woodland surrounding a brass foundry in Sweden. Concentrations vary decidedly between species. The mosses frequently show higher concentrations than the lichens. The use of different monitor species in a deposition survey without interspecies calibration is not advised. Calibration factors for concentrations in different species can be calculated from the mean concentrations in each species. With the help of the factors, concentrations in a species not found in a certain site can be estimated from concentrations measured in any of the other species sampled. The applicability of the reported calibration factors to surveys in other regions is discussed. Where these factors are not applicable, local calibration factors for indicator species of interest can be set up using the method presented.