Fish Remain High in Selenium Long after Mountaintop Coal Mines Close

Area of Science:

• Environmental Science
• Ecotoxicology
• Aquatic Ecology

Background:

• Mountaintop removal coal mining produces waste rock that releases selenium.
• Selenium bioaccumulation in fish can harm or extirpate downstream communities.
• Long-term selenium impacts from closed coal mines are not well understood.

Purpose of the Study:

• To investigate the long-term effects of mountaintop removal coal mining on selenium levels in fish populations.
• To assess if selenium contamination persists decades after mine closure and reclamation.

Main Methods:

• Collected fish tissue samples from Crowsnest Lake, downstream of the closed Tent Mountain Coal Mine.
• Measured selenium concentrations in fish tissues and compared them to established guidelines.
• Compared selenium levels in fish from Crowsnest Lake to those from 29 reference lakes without coal mining in their watersheds.

Main Results:

• Fish in Crowsnest Lake exhibited high selenium concentrations (5-26 μg/g dry weight), exceeding safe guidelines.
• These selenium levels are among the highest documented in scientific literature.
• Reference lakes showed significantly lower selenium concentrations in fish (0.2-2.5 μg/g dry weight).

Conclusions:

• Mountaintop removal coal mines pose a persistent threat to downstream fish populations, even decades after operations cease.
• Selenium contamination from historical coal mining can remain a significant ecological risk long after mine closure and reclamation.
• Continued coal mine development could further jeopardize the sustainability of fisheries like the one in Crowsnest Lake.