Dynamic Environment & Ecosystem Health Research

Legacy gold mine tailing contaminants
Linda, Emily and Julianne sampling, 2015

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Approaching a century-old legacy of arsenic and mercury contamination.

Note: We are continuing this research in 2020-2021. If you are interested in potential applications of our research, joining our research group or would like to contribute to our data analyses, please email Dr. Linda Campbell.

Waste materials ("tailings") from mining activities which took place in the 1800's can remain contaminated and toxic even over 100 years later. This is a national and international issue.  The DEEHR group is developing biomonitoring and remediation approaches for impacts of those tailings on freshwater ecosystems and organisms which rely on those freshwater resources. Our focus is on Nova Scotia legacy gold mine tailings, and our goals are to develop methodology which can be used to remediate not only those sites but can also be applied to similar impacted sites around the world.

Nova Scotia has a long history of gold mining going back to the mid-1800’s. There are over 360 gold mines in 64 historic gold mining districts in the Cambro-Ordovician Meguma Supergroup, stretching over a 300-km length of NS. Between 1862 and the mid-1940’s, 1.2 million troy ounces of gold were extracted, typically using mercury amalgamation techniques. Due to a lack of environmental regulations in the 1800’s, there is a modern legacy of three million tonnes of finely-ground contaminated waste tailings.


Mercury and arsenic remain elevated and of concern even 100 years later. Mercury-recovery techniques were practiced, but frequently 10 – 25% of mercury was lost to the environment through various means at each ore processing site. It has been conservatively estimated that a total of 3.7 to 9.1 tonnes of mercury may have been released to the NS environment from the 1850’s to the 1940’s. Since the original ore also included arsenopyrite and other arsenic-bearing pyrites, the gold-mine tailings also contain elevated arsenic. After processing, untreated tailings were frequently slurried into nearby freshwater systems without regard for the consequences. The legacy of localized tailing wastes near freshwater sites in 64 gold-mine regions has resulted in multi-generational chronic exposure to mercury, arsenic and other toxic elements for wildlife and humans.  Many sites across Nova Scotia still bear the visible scars of this extensive mining and processing a century later.

Michael & Guari at Montage (Montage photo)

We are doing something about this major environmental issue. There has been many excellent studies of arsenic and mercury exposure and impact in terrestrial ecosystems and geology. However, there is a significant knowledge gap for aquatic ecosystems of Nova Scotia, with only a few publications and reports on this topic.

The DEEHR team is carrying out several investigations looking at this significant environmental and industrial issue for Nova Scotia, in collaboration with Natural Resources Canada, Nova Scotia Energy & Mines Geosciences Branch, and many others. Projects include:
  • Studying the bioaccumulation and distribution of arsenic and mercury in living organisms across the province to assess the potential risk of gold mine tailing wastes to aquatic ecosystems.
  • Assessing dust, air and rain samples for mercury and arsenic from legacy gold mine tailings, including lichen collections.
  • The potential of conifer dendrochronology and dendrochemistry analyses to assess mercury and arsenic fluxes.
  • Paleoecology analyses of sediment cores for impacts of tailing contaminants.
  • Establishing ecotoxicology testing of key species in the laboratory to examine the rate of bioaccumulation, speciation, reduced functionality and lethality of the toxic tailings.
  • Developing a low-cost additive and capping methods to potentially significantly reduce the risk and toxicity of toxic gold mine tailings to terrestrial and aquatic biota as well as to humans.
  • Using remote sensing, LiDAR and other tools to create spatial databases of the extent and distribution of legacy gold mine tailings in Nova Scotia.
  • Rephotography project using historical photographs to assess changes through time since 1860's.

DEEHR members working in the laboratory.

RESOURCES:

DEEHR Resources
  • Brochure about contaminated historical gold mine tailing issues in Nova Scotia created by Peter Opra. Link to PDF file. (Created as a part of Clean Youth Internship outreach project).
  • Dr. Emily Chapman's seminar on low-dose selenium additives for reducing toxicity of gold mine tailing waste to earthworms. Link to You-tube video.
  • Molly LeBlanc's Three Minute Thesis talk "Not All That Glitters: Assessing Environmental Effects of Abandoned Gold Mines". Link to You-tube video. PDF transcript.
DEEHR Publications
  • ME LeBlanc, MB Parsons, EEV Chapman & LM Campbell. 2020. Review of Ecological Mercury and Arsenic Bioaccumulation within Historical Gold Mining Districts of Nova Scotia. Environmental Reviews. https://doi.org/10.1139/er-2019-0042.  Uncorrected proofs (PDF).  CBC article about the review paper. Link.
  • EEV Chapman*, J Robinson*, J Berry & LM Campbell. 2016. Can a low-dose selenium (Se) additive reduce environmental risks of mercury (Hg) and arsenic (As) in old gold mine tailings? Water, Air, & Soil Pollution.https://doi.org/10.1007/s11270-016-2909-9 Read online for free: http://rdcu.be/mFfT.
  • EEV Chapman*, C Moore & LM Campbell. 2019. Native plants for revegetation of mercury and arsenic-contaminated historical mining waste — Can a low-dose selenium additive improve seedling growth and decrease contaminant bioaccumulation?  Water, Air, & Soil Pollution. https://doi.org/10.1007/s11270-019-4267-x. Read online for free: https://rdcu.be/bP9M7.
  • Molly LeBlanc. 2019. MSc Thesis. "Bioaccumulation and transfer of mercury and arsenic in aquatic invertebrates and emergent insects at historical gold mine tailing sites of Nova Scotia" Link to download page.
  • Michael Smith, Linda Campbell & Carrie Rickwood. 2020. Lichens as biomonitors of dust and air quality biomonitors at a contaminated site.  Research Proposal Poster. Saint Mary's University. Figshare. https://doi.org/10.6084/m9.figshare.12086661.v1.
  • Michael Smith et al. 2020. Maps of sampling grids. Lichens as dust and air-quality biomonitors at a gold mine tailings site in Nova Scotia, Canada. Figshare. https://doi.org/10.6084/m9.figshare.12086205.v1.

External resources:
MEDIA MENTIONS
  • Port Wallace development & Montague legacy gold mine tailings. Halifax Examiner article by Joan Baxter. Link.
  • CBC news article about Molly LeBlanc's review paper on As & Hg bioaccumulation in biological organisms in NS.  Link.
  • CBC News article about the Conceptual Closure plans for Goldenville and Montague. Link.
  • 95.7 interview by Katie Hartai with Dr. Chapman about developing an approach for remediation with local plants. Link. Transcript PDF Link.
  • CBC News article about the NS Lands Inc RFP for Montague and Goldenville and Dr. Campbell's input: Link.
  • Halifax Examiner article by Joan Baxter about legacy gold mine tailings in Nova Scotia: Link.
  • CBC News article about the Public Service Announcement re: Barry's Run, Dartmouth and legacy gold mine tailings from Montague. Link.

Panorama of Muddy Pond with tailings at bottom and 3 people working at a distance along the shore
Headings
- Legacy of gold mining impacts in Nova Scotia.
- Mercury and arsenic issues.
 - NS Gold Mine Contaminants
- Useful resources.

Molly with a short sediment core sample.
All images and content copyright (c) Linda Campbell and other members of Dynamic Environment & Ecosystem Health Research Group. Map of gold-bearing deposits is from the Canadian Geographic Magazine (Sept/Oct 1994).