Historical and current atmospheric deposition to the epilithic lichen Xanthoparmelia in Maricopa County, Arizona

• Published in: Environmental pollution (1987) Vol. 125; no. 1; pp. 21 - 30
• Main Authors: Zschau, T., Getty, S., Gries, C., Ameron, Y., Zambrano, A., Nash, T.H.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier Ltd 01.01.2003; Elsevier
• Subjects: Air Pollutants - adverse effects; Air Pollutants - analysis; Air Pollution - analysis; Analysis methods; Animal, plant and microbial ecology; Applied ecology; Applied sciences; Arizona; Atmospheric pollution; Biological and medical sciences; Cadmium; Cadmium - analysis; Copper; Copper - analysis; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on plants and fungi; Environmental Monitoring - methods; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Lead; Lead - analysis; Lichens; Lichens - chemistry; Lichens - drug effects; Nickel; Nickel - analysis; Pollution; Praseodymium - analysis; Spectrum Analysis; Trace Elements - adverse effects; Trace Elements - analysis; Zinc; Zinc - analysis; United States; North America; Arizona; America; Cadmium; Lichens; Lead; Nickel; Copper; Arizona; Zinc; Chemical analysis; Atmospheric fallout; Biological indicator; Spatial variation; Time variation; Heavy metal; Trace element; Epilithic species; Trend analysis; Pollution source inventory; Lichenes; Air pollution; Sampling; Thallophyta; Concentration distribution
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/S0269-7491(03)00088-5

Spatial variation of elemental deposition to lichen receptors across Maricopa County, Arizona, USA is documented for 1998 and historical trends relative to 1974 are documented. Spatial patterns of atmospheric deposition of trace elements to an epilithic lichen were assessed using a spatial grid of 28 field sites in 1998 throughout Maricopa County, Arizona, USA. In addition, samples of Xanthoparmelia spp. from Arizona State University lichen herbarium material (1975–1976) was utilized for a limited number of sites in order to explore temporal trends. The lichen material was cleaned, wet digested and analyzed by ICP-MS for a suite of elemental concentrations [antimony (Sb), cadmium (Cd), cerium (Ce), chromium (Cr), cobalt (Co), copper (Cu), dysprosium (Dy), europium (Eu), gadolinium (Gd), gold (Au), holmium (Ho), lead (Pb), lutetium (Lu), neodymium (Nd), nickel (Ni), palladium (Pd), platinum (Pt), praseodymium (Pr), samarium (Sm), scandium (Sc), silver (Ag), terbium (Tb), thulium (Tm), tin (Sn), uranium (U), ytterbium (Yb), yttrium (Y), and zinc (Zn)]. Cluster analysis and principal component analysis suggest three major factors, which, depending on regional aerosol fractionation, explain most of the variation in elemental signatures: (1) a group of widely distributed rare earth elements (2) a highly homogenous Co, Cr, Ni, and Sc component representing the influence of mafic rocks, and (3) anthropogenic emissions. Elemental concentrations in Maricopa County lichens were generally comparable to those reported for relatively unpolluted areas. Only highly urbanized regions, such as the greater Phoenix Metropolitan Area and the NW corner of the county, exhibited elevated concentrations for Zn, Cu, Pb, and Cd. Lead levels in lichens have fallen over the last 30 years by 71%, while Zn concentrations for some regions have increased by as much as 245%. From the spatial pattern of elemental deposition for Cd, Cu, Ni, Pr, Pb, and Cu, we infer that agriculture, mining, industrial activities, and traffic probably are the major air pollutant sources in Maricopa County.