Use of a single epiphyte lichen species Hypogymnia physodes as an indicator of air quality in northern Ontario / by Helmut N. Pfeiffer

It has been determined that lichens are excellent indicators of regional
\nair quality, since they are long-lived and totally dependent on atmospheric
\nsources for nutrients. In the summer of 1987, samples of the epiphytic
\nlichen, Hypogymnia physodes (L.) Nyl. were collected from 46 sites in
\nnorthwestern Ontario, Twenty-eight of these sites were sampled around
\nthe city of Thunder Bay, Samples were also collected from 6 sites around
\neach of the northwestern Ontario communities of Kenora, Ignace and Wawa,
\nMorphological observations of the lichens were made before sampling.
\nChemical analyses were carried out and levels of A1, As, Cd, Cu, Fe, Hg,
\nMg, Pb, Sand Zn were determined for each sample by atomic emission
\nspectrometry.
\nOverall levels of elements were low in relation to levels reported in
\nother literature. The ranges of concentrations (ppm) of elements in H.
\nphysodes sampled around Thunder Bay were as follows: Al: 185 - 706;
\nAs: 0,9 -7,1; Cd: 0,2 - 1,2; Cu: 0,8 - 6,9; Fe: 114 - 691; Hg: 0,6 - 5,8;
\nMg: 69 - 393; Pb: 3,9 - 48; S: 42 - 434; Zn: 7 - 92, The area to the south
\nand southwest of Thunder Bay had the highest levels of most elements.
\nThe area to the west had the lowest levels. The Kenora, Ignace and Wawa
\nareas had low levels of most elements relative to Thunder Bay results.
\nLevels of contaminants indicated an inverse relationship existed
\nbetween levels of pollutants and the distance from the pollution source.
\nA number of morphological observations correlated significantly with
\nlevels of certain elements, suggesting possible indicator value.

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