Large scale air monitoring: lichen vs. air particulate matter analysis

Biological indicator organisms have been widely used for monitoring and ban king purposes for many years. Although the complexity of the interactions b etween organisms and their environment is generally not easily comprehensib le, environmental quality assessment using the bioindicator approach offers some convincing advantages compared to direct analysis of soil, water, or air. Measurement of air particulates is restricted to experienced laborator ies with access to expensive sampling equipment. Additionally, the amount o f material collected generally is just enough for one determination per sam pling and no multidimensional characterization might be possible. Further, fluctuations in air masses have a pronounced effect on the results from air filter sampling. Combining the integrating property of bioindicators with the world wide availability and particular matrix characteristics of air pa rticulate matter as a prerequisite for global monitoring of air pollution i s discussed. A new approach for sampling urban dust using large volume filt ering devices installed in air conditioners of large hotel buildings is ass essed. A first experiment was initiated to collect air particulates (300-50 0 g each) from a number of hotels during a period of 3-4 months by successi ve vacuum cleaning of used inlet filters from high volume air conditioning installations reflecting average concentrations per 3 months in different l arge cities. This approach is expected to be upgraded and applied for globa l monitoring. Highly positive correlated elements were found in lichens suc h as K/S, Zn/P, the rare earth elements (REE) and a significant negative co rrelation between Hg and Cu was observed in these samples. The ratio of con centrations of elements in dust and Usnea spp. is highest for Cr, Zn and Fe (400-200) and lowest for elements such as Ca, Rb, and Sr (20-10). (C) 1999 Elsevier Science B.V. All rights reserved.