Impacts of arsenic and sulphur dioxide contamination from mining activities on forest health near Yellowknife, NWT

Growth patterns of jack pine (Pinus banksiana) near Giant Mine in Yellowknife, NWT were studied in order to assess the impacts of mine activities on tree-growth and forest health during the 20th century. Differences in arsenic (As) and sulphur (S) concentrations in tree-rings and surface soil and differences in groundcover species richness (GCSR) were compared for sites downwind (contaminated) and upwind (reference) of the mine. Concentrations of As and S in soil and tree-rings were significantly higher at contaminated versus reference sites, while soil pH was not significantly different. Soil-As and soil-S concentrations decreased significantly with increasing distance of study sites from the mine. Lower GCSR at contaminated sites compared to reference sites corresponded to higher levels of soil-As concentrations. Tree-ring concentrations did not reflect changes in As emissions from Giant Mine. However, changes in calcium (Ca) concentrations in tree-rings coincided with calcine management activities. The onset of activity at Giant Mine coincided with divergences in growth patterns between mean contaminated and reference chronologies unprecedented in the pre-operational period covered by this study (1900-1948). Due to constraints in data availability, differences in the climate-growth response of jack pine at contaminated and reference sites remain uncertain.