After a very interesting student presentation on heavy metal pollution in our BIOL4095 class, I thought I should share my own experience visiting the Giant Mine remediation site in Northwest Territories.
The Giant Mine was a large gold mine located just outside of Yellowknife, NWT. The mine entered production in 1948 and ceased operation in 2004. Over its time of operation, the mine produced 220,000 kg of gold. But the gold smelting process produced 237,000 tons of Arsenic (As) trioxide dust, a highly dangerous inorganic compound and a well known carcinogen. This makes Giant Mine the worst contaminated site in Canada.
Currently the remediation work is composed of: (1) freezing the 237,000 tons of As using the frozen block method; (2) cleaning up tailing ponds and surrounding soil, including Baker Creek and eight open pits; (3) water clean-up and release into Baker Creek which flows into Grate Slave Lake; and (4) revitalizing the surrounding vegetation. This remediation project will cost Canadian tax payers $1-billion.
For more information on the Giant Mine remediation project here.
However, there seemed to be a somewhat flawed approach to remediation work currently undertaken by the Canadian government, as they are dealing with restoring the environment but do not have a single biologist on the remediation team. Although land and water treatment and As removal has proven to be successful. There is, however, an apparent issue with revitalizing the site’s vegetation.
During the tour of the Giant Mine, the remediation manager explained that vegetation restoration consisted of spread of a mixture of seeds of plants, both local and from the South (BC and Alberta). But in my opinion, this raises issues dealing with the introduction of foreign species into the environment which may become invasive, especially in the face of rapid warming climate in the North.
The lab I am working in at Laurier university is looking at different plants from contaminated regions near the Giant Mine including Black Creek, and comparing their growth to soil unaffected by As contamination. Helping a graduate student, I had the first hand chance to see the effects of As on these plants: plants growing in soil with high As concentrations had severely reduced growth rates compared to plants growing in lower As concentrations. Even more interestingly, plants growing in high As concentration produced red leaves, compared to green leaves produced under low As concentrations.