LE3 .A278 2021

2021

O'Driscoll, Nelson
Campbell, Linda

Acadia University

Bachelor of Science

Honours

Environmental Science

Earth & Environmental Sciences

Tree cores and surface soil samples were collected from four historical gold mine tailings sites near the Halifax Regional Municipality (HRM) for mercury (Hg) and arsenic (As) analyses. Five spruce trees (either Picea glauca or Picea mariana) were cored from each site, and the year of growth estimated from tree ring counts. We found that average surface soil (silt+ clay fraction) total Hg and As concentrations from all mine tailings sites exceeded Canadian Health guidelines for acceptable soil Hg (500 μg/kg) and As (12 mg/kg) concentrations in residential areas. We found most tree core samples were below the method detection limit (MDL) for Hg in samples from the Montague, Oldham and Muddy Pond tailings sites (MDL ranging 1.3-4.2μg/kg). with the notable exception of the Old Stamp Mill site in Montague Mining District. Mercury in tree ring segments for the Old Stamp Mill site ranged from 0.9to 43.1 μg/kg, with a MDL of 2.0 μg/kg. However, regression analysis for this site did not show a consistent trend between Hg concentration and time between cores. Additionally, using non-parametric Spearman’s correlations, no significant correlation (n=26, p- value=0.08) was found between Hg concentrations in tree bark and Hg in surface soils. Unfortunately, we were not able to measure As in tree cores at the time of this writing due to COVID-19 related delays. The results of this study show that historical gold mine tailings sites in Nova Scotia have soils that are highly contaminated with both Hg and As, and more research is needed to confirm if spruce trees are reliable indicators of mercury bioaccumulation at those sites.This reinforces the need for future studies on the bioaccumulation and effects of both contaminants in living organisms around legacy gold mine tailing sites

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https://scholar.acadiau.ca/islandora/object/theses:3563