J. Phys. IV France 107 (2003) 921
Historical patterns of metal atmospheric deposition to the epilithic lichen Xanthoparmelia in Maricopa County, Arizona, U.S.A.T.H. Nash III1, C. Gries1, T. Zschau1, S. Getty2, Y. Ameron12 and A. Zambrano1
1 Department of Plant Biology, Arizona State University, Box 871601, Tempe, AZ 85287-1601, U.S.A.
2 Department of Geosciences, University of New Mexico, Albuquerque, NM, U.S.A
Temporal patterns (1974 to 1998) of atmospheric deposition of 6 metals to an epilithic lichen were assessed using a spatial grid of 6 (of 28) field sites throughout Maricopa County, Arizona, U.S.A. The lichen material was cleaned, wet digested and analyzed by ICP-MS for a suite of éléments: (cadmium [Cd], copper [Cu], lead [Pb], platinum [Pt], tin [Sn], and zinc [Zn]). Copper, lead and tin have ail exhibited declines at some sites; whereas zinc and platinum have increased at most sites. Causes of the temporal patterns arc inferred to be related to closure of a copper smelter, change in gasoline type (now unleaded), dramatic increases in traffic volume, rapid development of the urban area and expansion of the Phoenix industrial base.
© EDP Sciences 2003