Impact of ambient trophospheric O-3, CO2, and particulates on the epicuticular waxes of Aspen clones differing in O-3 tolerance

Epicuticular waxes of trembling aspen (Populus tremuloides M i c h x.) clon es differing in O-3 tolerance were examined for three growing seasons (1995 -1997) at three localities (Rhinelander, Wisconsin -clean and control site; Kalamazoo, Michigan -moderate pollution loading and Kenosha, Wisconsin hig h pollution loading) in the Lake States region of the USA. Statistical diff erence was found in the concentration of Al, As, Ca, Cd Cu, Fe, Mn, N,Ni, P , Pb, S, and Zn in the aspen foliage. Particulates on the leaves surfaces a nd in the stomata at the three sites include Al, Ga, Fe, Si, Mg, Ma, S, Th, Ti and Y. These elements are typical for particles from industrial sources . Fungi effect was observed on leaves from all localities. Differences in e picuticular wax structure, as determined by scanning electron microscopy we re found between these sites with the most severe impact being found at the Kenosha site. These include severe erosion of waxes, and occlusion of stom ata. The results; suggest that O-3 pollution of the Kenosha and Kalamazoo s ite show significant negative impact on epicuticular waxes of aspen and tha t these impacts are the most severe on the O-3 sensitive clones.