Methodological investigations into low technology monitoring of atmospheric metal pollution: Part 3—The degree of replicability of the metal concentrations

Methodological investigations were undertaken to determine the replicability of the concentrations of metals in a number of low technology samplers. Most of these samplers were subsequently used for the main monitoring survey of atmospheric metal pollution in Armadale, an industrial town in central Scotland. The indigenous samplers included Hypnum (moss), Lecanora (lichen), Agropyron (grass) and surface soils. The transplanted samplers included spherical moss bags (acid washed), Hypogymnia (lichen) and tak (synthetic fabric). Other samplers were added for purposes of comparison: translated flat moss bags (acid washed), another two types of spherical moss bag (fresh moss and water washed), dead Hypogymnia and a fruticose lichen. Of the low technology samplers selected for use in the main monitoring survey, all except the surface soils gave concentrations of most metals that were well within an acceptable range of variability. However, metals such as Cr and Ni, which were present in low concentrations, showed values which were significantly less replicable than those of the other metals. Of the comparison samplers, the flat moss bags, water-washed spherical moss bags and the dead Hypogymnia gave very replicable concentrations of metals; the fresh moss bags and the fruticose lichens gave the least consistent metal values.