ST. CLAIR, SAMUEL B.1*, LARRY L. ST. CLAIR2, NOLAN F. MANGELSON3, DARRELL J. WEBER2, and ALAN WHALON4. 1Department of Plant Physiology, The Pennsylvania State University, State College, PA 16803; 2Department of Botany and Range Science, Brigham Young University, Provo, UT 84602; 3Department of Chemistry, Brigham Young University, Provo, UT 84602; 4Chiricahua National Monument, Willcox, AZ 85643. - Using Cu/Zn ratios in lichens to determine anthropomorphic sources of copper pollution.
Accumulation of airborne pollutants by lichens is, in part, the basis
for their use as bioindicators of air quality. However, direct
correlations between emission sources and pollutant element
accumulation by lichens are often difficult to document. In this study
copper accumulation patterns by lichens, along a copper pollution
gradient, were examined. Data from four locations, along a 1500-km,
north-south transect, with increasing distance from copper smelting
activity (southeastern Arizona, southwestern New Mexico, and adjacent
parts of Mexico), were collected. Lichens, representing two growth
forms (foliose and fruticose), were collected from each study site.
Copper and zinc concentrations were determined for all samples using
PIXE analysis. In addition, ambient air concentrations of copper and
zinc for all sites were obtained from the AQG web site
(http://improved.cnl.ucdavis.edu/). Correlation of copper
concentrations in lichen samples and ambient air along the transect
showed a highly significant positive linear relationship (R2=.97).
Data also showed that foliose lichens accumulated approximately twice
as much copper as fruticose species. Cu/Zn ratios from lichen samples
and ambient air were correlated along the transect and also showed a
highly significant positive linear relationship (R2=.98). Background
Cu/Zn ratios are < 0.5. Values from the two sites nearest the copper
smelting operations ranged between 0.6 and 1.45, while the “clean”
sites had values between 0.1 and 0.35. Substrate Cu/Zn ratios from the
Arizona location were all below 0.5. These patterns support the use of
element ratios in accurately predicting elevated element
concentrations in lichen thalli and making more effective decisions
relative to possible sources of pollutant elements.
Key words: Bioindicators, Copper, Element Ratios, Lichens, Zinc