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TitleDendrochronological and dendrogeochemical investigations of Smelter emissions impacts in the Rouyn-Noranda region
AuthorBégin, C; Savard, M M; Parent, M; Marion, J; Smirnoff, A
SourceDendrochronological, Environmental Change and Human History: 6th International conference on Dendrochronology, extended abstracts; 2002 p. 11-12
LinksAbstract - Résumé
Alt SeriesEarth Sciences Sector, Contribution Series 20080308
MeetingSaskatoon 2002; International conference on Dendrochronology; Québec; CA; August 22-27, 2002
Mediapaper; on-line; digital
NTS32D/02; 32D/03; 32D/06; 32D/07
Lat/Long WENS-79.5000 -78.5000 48.5000 48.0000
Subjectsenvironmental geology; geochemistry; dendrochronology; vegetation; smelters; pollution; pollutants; environmental studies; environmental analysis; environmental impacts; stable isotope studies; carbon isotopes; carbon ratios; Horne smelter; emissions
AbstractAmong existing environmental monitoring techniques, the dendrogeochemical approach combining tree-ring physical parameters, stable isotope ratios and elemental concentrations is particularly relevant because it can provide high-resolution temporal records of complementary tracers sensitive to environmental changes. The approach is based on the assumption that physical features and geochemical contents of a given tree ring reflect environmental conditions that prevailed during the year it was formed. In this study we have applied this approach to evaluate the impact of the Horne smelter emissions on the coniferous vegetation and the tree growth. The Horne smelter has been emitting airborne metal particulates and toxic gases such as SO2 since it began operating in 1928. Six old-growth black spruce stands distributed along a 120 km southwest-northeast transect downwind from the Horne Smelter were investigated. At each site, a set of 15-20 spruce trees were sampled for standard dendrochronological investigations and, among each set, 3 specimens were selected for geochemical analyses. At the test site, 9 km NE from the smelter, dendrogeochemical data show a first order abrupt 13C shift of +4 permil right after the smelter started its activities. For the same period, nutrients ([Ca]) show concentrations decreasing by 40% (avg). These first order shifts inversely correlate and reflect an important stomatal closure. In contrast to nutrients and stable isotopes, concentrations of heavy metals (Pb, Cd) increased gradually from 1948 to 1970, illustrating a slower rate of change in soil than in air chemistry. Dendrogeochemical profiles from distal sites along our transect show a decreasing effect of smelter emissions at increasing distance from the source. The tree growth response in the region is mainly controlled by spring temperatures (April) and by precipitations of the previous late growing season. Indexed tree-ring chronology produced for each site show synchronized periods of slow growth caused by insect defoliation. This tree-ring response masks the actual impact of a high level of contamination on radial growth. However, the densitometric analysis indicates that latewood density is quite sensitive to contamination as the test site displays a significant correlation between the mean latewood density and carbon isotope profiles. This correlation suggests that trees contaminated by smelter-emissions reduce their growth rate earlier than uncontaminated trees in the growth season.