Strategies in sampling and sample handling in the context of large-scale plant biomonitoring surveys of trace element air pollution

Aspects of sampling and sample handling in the context of large-scale plant biomonitoring surveys of trace element air pollution are addressed. Topics such as survey goals and planning, choice of elements, biomonitor species (lichens, mosses, bark), interspecies calibration, SO2 effects, local variation, comparability of results, sample homogeneity, the problem of soil-derived elements, and elemental analysis are discussed. The paper stresses the need for stringent accuracy control, indicates the importance of local variation in the concept of the survey, and underlines the relevance of multi-elemental analysis. Furthermore, factor analysis is indicated as a powerful mathematical tool in dealing with the presence of both soil particle contamination and soil-derived absorbed elements.