A recent study by the U.S. Geological survey has found high levels of Mercury and Selenium in fish and other food sources along the Colorado River in Glen Canyon and Grand Canyon National Park. Arizona Public Radio’s Justin Regan reports.
The study found the two chemicals to be at potentially deadly levels in minnows and invertebrates like snails and algae. Mercury and selenium are known to reduce rates of reproduction and survival in affected wildlife. However, toxicity levels in predatory fish, like rainbow trout, were not high enough to trigger a warning for human consumption.
The USGS says the study “adds to a growing body of evidence” that remote ecosystems can still be affected by the long-range transportation of deadly chemicals. Possible sources include naturally occurring selenium-rich soil further upstream and power plant pollution. Additional studies are planned to monitor potential risks to humans.
