Legacy pollution in Nova Scotia: Historical artisanal goldmining has elevated Hg and As concentrations in Ponhook Lake sediments
* Ben Gooley¹, Ian Spooner1, Nick Hill2, Nelson O’Driscoll¹
¹Department of Earth and Environmental Science, Acadia University, Wolfville, Nova Scotia
2Southwest Nova Biosphere Reserve Association, Yarmouth, Nova Scotia
Historic artisanal and small-scale gold mining (ASGM) in Nova Scotia has left a legacy of mercury (Hg) and arsenic (As) contamination in lacustrine ecosystems across the province. These contaminants may pose a risk to aquatic organisms due to their ability to bioaccumulate and cause toxic effects. The Malaga Gold District, situated between Ponhook and Molega lakes, is a historic ASGM site. Our research aimed to quantify contamination of Hg and As in shoreline sediments and invertebrate communities of Ponhook Lake. In summer 2025, we collected sediment samples from transects along the northern and southern shores of the lake. These sediments were dried and sorted to a consistent silt-clay texture through a 200-µm stainless steel sieve. Sorted sediments were analyzed for total mercury (THg) and total arsenic (TAs) using a NIC MA-3000 direct mercury analyzer and Epsilon 1 X-Ray Fluorescence for As. Preliminary analyses showed that there are elevated concentrations of Hg (178 – 5788 ng g-1; n = 16) and As (106 - 1060 µg g-1; n = 10) in localized sediments near the mine tailings. We also summarize new data collected for THg, methylmercury, and TAs in aquatic invertebrates collected in summer 2026. Results of our research may inform future remediation efforts and policy decision-making at Ponhook and other legacy gold mines in Nova Scotia.
Keywords: arsenic, bioaccumulation, goldmining, legacy pollution, mercury
* student presentation