Methodological investigations into low technology monitoring of atmospheric metal pollution: Part 1— The effects of sampler size on metal concentrations

Methodological investigations were undertaken to determine the optimal sizes of three types of transplanted low technology sampler—the spherical moss bag, the lichen Hypogymnia physodes and the tak sampler (a synthetic fabric). The optimal sizes were qualified as those providing, for most metals, a combination of high concentrations, reliable values and dimensions which take into account practical considerations. Various sizes of these samplers were exposed for a period of 2 months near a source of atmospheric metal pollution. An analysis of the results allowed optimal sizes of these samplers to be recommended for future surveys: for the spherical moss bags, a dry weight of 0·1 to 0·2 g; for Hypogymnia, a thallus diameter of 0·8 to 1·2 cm and, for the tak samplers, a surface area of 70 cm2.