Arsenic heritage in lake bottom sediments from historic NS mine worries researchers

Halifax — Findings from studies explaining the heritage of arsenic left in lake sediments near the abandoned Halifax gold mine warn senior cancer researchers.

According to a paper published Monday in the journal Science of the Total Environment, core dating samples taken from the bottom of Lake Charles are 4,960 milligrams / kilogram, more than 280 times the “expected biological hazard” level. I found arsenic.

The site is located downstream of the historic Montague mine, where a series of gold rushes produced 121,000 tonnes of arsenic-rich tailing from the 1860s to 1940s.

In addition to high levels of carcinogens, samples suggest that arsenic in the deepest sediments of the lake is actually rising closer to the water itself.

Joshua Kurek, an environmental scientist and co-author of the study at Mount Allison University in Sackville, New Brunswick, said in a recent interview that the approach to arsenic lakes after a very long time has passed. He said it was unexpected.

“We tend to think of lake bottom sediments as sinks for many substances … but pollutants from the mining industry, which ended 80 years ago, slowly move up the core and approach the sediments. There may be-water boundaries, “he said.

“If the environmental conditions at the bottom of Lake Charles change, some of the pollutants trapped in the sediments can be released into the water column.”

According to the Federal Fisheries Department, the popular swimming and boating lakes on the outskirts of Halifax already have high levels of 11 micrograms of arsenic per liter, twice the Canadian water quality guidelines for aquatic conservation. And there are more than 50 other lakes in the area. data.

In a state full of abandoned mines, a journal article expressed concern to Dr. Graham Deler, director of research at the Department of Pathology, Dalhousie University School of Medicine.

Halifax-based researchers lead a national team of experts investigating carcinogens that affect people’s risk of developing cancer.

In an interview last week, he often hears messages about the cancer risk that the general public is exposed to radon, but many are unaware of the risk of long-term exposure to arsenic and its association with various cancers. Hmm.

“As arsenic and mercury levels rise from this deposit, the risk of skin cancer from swimming and playing in the water may increase,” he said after reading a Lake Charles study.

Delea is about to launch an arsenic awareness campaign. He is seeking funding to provide information to areas at high risk of pollution, such as downstream of abandoned gold sites.

He said the program would invite people to test well water and screen for personal arsenic exposure through toenail sampling.

“Our past mining ghosts are back,” he said.

Mr. Kurek said the upward movement of arsenic in Lake Charles may be related to the city’s impact on the body of water.

Freshwater ecosystem experts say that nutrients such as fertilizers that flow in from surrounding properties have biological processes that can deplete oxygen in deeper areas, and this chemical change in the water is associated with an increase in arsenic. Seems to be doing.

Hot water and other climate change effects could also have an impact, which could accelerate the chemical processes that deplete the lake’s oxygen, he added.

Lake Charles’ study suggests that further research is needed to understand the effects of arsenic and mercury on plants, fungi, invertebrates, soft animals, fish and mammals in Nova Scotsia’s historic gold mining area. It will be done about a year after the study.

A 2020 paper published in the journal Environmental Reviews found that only 18 of Nova Scotia’s 64 gold districts were analyzed for mercury and arsenic accumulation in various forms of life.

In July 2019, the state government announced that it was spending $ 48 million on cleaning up the Montague site and Golden Building site in Geisbara County. Overall, they are looking at a list of 69 abandoned mining sites, including 24 gold mines in the royal territory, to identify where containment and other work is needed.

This concludes that the state’s chief auditor has not fully investigated the potential pollution at many abandoned mine sites, which means that future tolls may be unknown to the government’s finances. I came in the same year that I published the report.

In a hearing with the legislative committee last month, Nova Scotia Land’s secretary-general, Donnie Burke, said restoration work at the Montague site is expected to begin by next year.

Alison Clark, the lead author of the latest treatise, completed the work at Mount Allison’s School of Biology, completing the treatise.

“I believe our research is a call for action to tackle tailing site restoration efforts,” she said.

In an interview, Linda Campbell, a professor of environmental science at St. Mary’s University and another co-author, said arsenic has been a “very long-term” component of the ecosystem.

She said the first step in repairing a contaminated area was to “stop the movement of the (gold) tailing material itself” in Montague and elsewhere.

Michael Tutton

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