Physics & Astronomy

Lichens, Bioindicators of Air Pollution: Analysis Using Accelerator Techniques

Nolan F. Mangelson^a, Larry L. St.Clair^b, Lawrence B. Rees^c, Dylan C. Argyle^a, Ryan Kelly^a,  Wesley D. Morin^a, Seth M. Washburn^a, Brett M. Clark^d, Patrick G. Grant^e, and Graham S. Bench^e

^aDepartment of Chemistry and Biochemistry,

^bDepartment of Botany and Range Science,

^cDepartment of Physics and Astronomy,

 Brigham Young University, Provo, Utah, 84602 USA

^dHoneywell Electronic Materials, Spokane, Washington 99216 USA

^eCenter for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, California 94550 USA

The lichen symbiosis has successfully adapted to almost all terrestrial ecosystems on earth, and  lichens have been used for many years as bioindicators of atmospheric pollution.  Minor and trace-element concentrations in lichens have been used as indicators of pollution sources and relative amounts of air pollutants.  Lichen samples have been collected and observations about lichen communities have been recorded at sites in the intermountain western United States as part of a base-line assessment of current air pollution conditions in this region.  Samples from over 600 of these lichens have been analyzed by proton induced x-ray emission (PIXE) for the determination of minor- and trace-element concentrations.  As an example of the use of these data, it has been shown that copper and zinc are good markers for air pollution from copper production industries.  Element concentration data also provide an opportunity to study some aspects of lichen physiology.  The microscopic distributions of minor and trace elements within the structure of a few lichen samples have been studied using the proton microprobe at Lawrence Livermore Laboratory.  These microscopic studies and the frequency distributions of calcium taken from the intermountain study provide strong evidence that lichens develop specific calcium-related adaptations in order to accommodate various habitat conditions.