Dendrochemical Investigation of Arsenic Exposure from Giant Mine on Spruce and Jack Pine Forests, Yellowknife, NWT.

Regions: North Slave Region

Tags: contaminants, mining impacts, forestry, chemistry

Principal Investigator: St-Onge, Sonia M (1)
Licence Number: 13985
Organization: Carleton University
Licenced Year(s): 2006
Issued: May 30, 2006
Project Team: Cindy St-Onge, Sir Sanford Fleming College Graduate (Research Assistant, N/A), TBD, Yellowknife High School Student (Research Assistant, Yellowknife High School), TBD, Yellowknife High School Student (Research Assistant, Yellowknife High School)

Project Description: The spruce and jack pine forest stands in certain areas surrounding the site of Giant Mine, north of Yellowknife, show signs of poor health; stunted growth, early leaf drops, and yellowed foliage. These symptoms may be attributed to the emissions of sulphur dioxide (SO2) and arsenic trioxide (As2O3) that were released into the atmosphere from 1949 to 1999 as by-products to the roasting process used to extract gold. The proposed research project, a Master of Science thesis, will investigate whether the health of forest ecosystems near Yellowknife has changed over the last century and, if so, whether or not these changes are related to arsenic and sulphur dioxide deposition from Giant Mine emissions. This will be accomplished by using tree-ring analysis and chemical analysis of forest soils and tree biomass.

Tree coring will be carried out at sixteen sites. These sites will be situated along four transect lines of 20-30 km in length in the vicinity of Vee Lake Road, Highway 4, Highway 3 and the eastern islands of Yellowknife Bay. Sites for tree coring will be accessed on foot or by canoe. Sites within the islands of Yellowknife Bay will be accessed by boat. Two cores (diameter of ~4.3 mm) will be removed from each tree using an increment tree borer. Approximately thirty trees (white spruce, black spruce or jack pine) will be sampled at each site. Measurements of tree height and diameter will be taken on site. The ring widths of each core will be compared with climate records and with arsenic and sulphur dioxide emissions from Giant Mine. A core from each site will be analyzed for arsenic content. The soil type will be determined at each site, and soil samples will be collected from the base of cored trees. A vegetation inventory will be conducted at each site in order to characterize the site. The leaf area index (LAI) will be determined. Clippings from groundcover and foliage from the sampled trees may be collected for alternate measurement of LAI and for analysis of arsenic content in the above ground biomass.

Copies of reports or papers arising from this research will be shared with interested parties. Copies of the thesis will be delivered to the Aurora Research Institute and Department of Indian and Northern Affairs office in Yellowknife.
The study will be conducted from July 11 to August 31, 2006 at the following locations: Vee Lake Road transect [from Giant Mine (62°30’30” 114°20’40”) to Greyling Lake (62°41’10” 114°20’40”)]; Yellowknife Bay transect [Giant Mine to Ruth Island (62°18’20” 114°15’30”); Highway 3 transect [62°30’30” 114°20’40”to 62°30’30” 114°43’50"]; Highway 4 transect [62° 30’30” 113° 57’40” to 62° 30’30” 113°25’00”].