Aa. Takar et al., CHEMICAL-CHANGES IN THE STEM MATRIX OF 3 TREE SPECIES EXPOSED TO FLUORIDE EMISSIONS FROM AN ALUMINUM SMELTER, Forestry Chronicle, 74(1), 1998, pp. 78-82
The principal objective of this study was to investigate the major org
anic and trace elemental composition of the stem tissues of three tree
species of a mixed forest on Cornwall Island in the St. Lawrence Rive
r, Ontario. This forest was exposed to atmospheric hydrogen fluoride (
HF) at levels >71 mu g F/m(3)/24 h from an aluminum smelter (Reynolds
Metals Co. Ltd.) for twenty years, followed by fourteen years of reduc
ed emissions (<40 mu g F/m(3)/24 h), which is still greater than the c
urrent Ontario air quality criterion for HF (0.36 mu g F/m(3)/24 h). I
ncrement cores were collected at breast height from white pine, red oa
k, and American beech from the study woodlot on Cornwall Island and at
a control site in Long Sault Provincial Park. Tree-rings were analyze
d for eight elements (fluorine, aluminum, manganese, magnesium, calciu
m, sodium, chlorine and potassium) and some major organic compounds (t
otal extractives, lignin and holocellulose). All three species from th
e study woodlot showed significant chemical compositional changes duri
ng the peak pollution and post-abatement periods. There was a substant
ial increase of the levels of total extractives (up to 167%), lignin (
up to 38%), fluorine, aluminum and manganese and a significant decreas
e of holocellulose content (up to 17%) in the stem tissues during the
period of HF exposure, compared to the pre-pollution period. In contra
st, trees from the control site showed no significant change in chemic
al composition in any of the three periods. Lower cellulose and higher
lignin and extractives concentrations potentially makes the wood weak
er and less suitable for dimension lumber and pulping.