Wildfires are leading to increased mercury levels in Pacific Northwest headwaters, according to a new survey from the U.S. Geological Survey.
What's happening?
The Oregon Capital Chronicle reported on the study, which looked at mercury and methylmercury levels in the headwaters of streams in Idaho, Washington, and Oregon. The publication noted that mercury is naturally occurring in rocks and soil but can turn into methylmercury — a highly toxic compound that accumulates in living organisms like fish and humans — under the right conditions.
The USGS survey sampled soil, water, sediment, instream leaf litter, streambed algae, and aquatic invertebrates in 36 headwater streams in watersheds one year after experiencing a wildfire event. They also studied 21 similar but unburned watersheds.
Ultimately, the scientists discovered that the mercury and methylmercury levels in water particles in fire-affected watersheds were 89% and 178% higher than in non-affected areas. They also found that mercury concentrations increased with the severity of a fire.
USGS research ecologist Collin Eagles-Smith told the Chronicle the team was "a little surprised" by the results.
Why is this survey concerning?
This study focused on headwater streams, which are at the top of watersheds. Therefore, scientists are concerned about the downstream implications.
"If that mercury is made more mobile and transports downstream, it could end up in reservoirs or larger rivers where there are predatory fish, top predators that humans would catch and consume," Collin Eagles-Smith told the Chronicle. "In those scenarios, there could be an increase in risk of exposure if that (mercury) is transported downstream to those other types of environments."
Mercury is a neurotoxin, according to the U.S. Environmental Protection Agency. Methylmercury in particular is a powerful neurotoxin, and consuming high levels can lead to poisoning with symptoms that include loss of peripheral vision, "pins and needles" feelings in extremities and the mouth, lack of coordination, and impairment of speech and hearing. Methylmercury can also affect unborn infants if their mother consumes contaminated fish — this can impact their cognitive thinking, memory, attention, language, fine motor skills, and visual-spatial skills.
As our planet continues to overheat, we can expect more severe wildfires, which increase the risk of even more mercury in streams and rivers.
What's being done about wildfires?
USGS Research Hydrologist Austin Baldwin, who led the study, told the Chronicle that prescribed burns might help keep mercury concentrations bound. Many land managers, including the U.S. Forest Service, look to prescribed burns as a way to rejuvenate forests and decrease the likelihood of catastrophic wildfires.
Meanwhile, it's critical that we try to curb the warming of our planet to help decrease wildfire risk. You can help by voting for pro-climate candidates. Reducing your reliance on planet-warming fuels is another way to make a change, as oil, coal, and natural gas account for more than 75% of heating pollution. You can achieve this through simple actions like taking public transit more or enrolling in community solar.
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