| dc.description.abstract | it has been determined that lichens are excellent indicators of regional
air quality, since they are long-lived and totally dependent on atmospheric
sources for nutrients. in the summer of 1987, samples of the epiphytic
lichen, hypogymnia physodes (l.) nyl. were collected from 46 sites in
northwestern ontario, twenty-eight of these sites were sampled around
the city of thunder bay, samples were also collected from 6 sites around
each of the northwestern ontario communities of kenora, ignace and wawa,
morphological observations of the lichens were made before sampling.
chemical analyses were carried out and levels of a1, as, cd, cu, fe, hg,
mg, pb, sand zn were determined for each sample by atomic emission
spectrometry.
overall levels of elements were low in relation to levels reported in
other literature. the ranges of concentrations (ppm) of elements in h.
physodes sampled around thunder bay were as follows: al: 185 - 706;
as: 0,9 -7,1; cd: 0,2 - 1,2; cu: 0,8 - 6,9; fe: 114 - 691; hg: 0,6 - 5,8;
mg: 69 - 393; pb: 3,9 - 48; s: 42 - 434; zn: 7 - 92, the area to the south
and southwest of thunder bay had the highest levels of most elements.
the area to the west had the lowest levels. the kenora, ignace and wawa
areas had low levels of most elements relative to thunder bay results.
levels of contaminants indicated an inverse relationship existed
between levels of pollutants and the distance from the pollution source.
a number of morphological observations correlated significantly with
levels of certain elements, suggesting possible indicator value. | |
