Grand Canyon Stretch of the Colorado River Threatened by Mercury Pollution
Even one of America's most iconic landmarks is not immune from pollution. The Grand Canyon segment of the Colorado River is suffering from exposure to toxic chemicals, including mercury, according to a study from the U.S. Geological Survey (USGS).
— Cary Institute (@caryinstitute) August 19, 2015
"Concentrations of mercury and selenium in Colorado River food webs of the Grand Canyon National Park regularly exceeded risk thresholds for fish and wildlife," the USGS team said in a statement. The concentrations of toxins in some fish were so high that they could be harmful if consumed by wildlife or humans. The researchers noted that their findings build further evidence that even extremely remote ecosystems, such as this stretch of the Colorado River, are "vulnerable to long-range transport and bioaccumulation of contaminants."
“Managing exposure risks in the Grand Canyon will be a challenge because sources and transport mechanisms of mercury and selenium extend far beyond Grand Canyon boundaries,” said Dr. David Walters, lead author of the study.
Researchers took samples from six sites along the nearly 250 miles of the Colorado River downstream from Glen Canyon Dam within Glen Canyon National Recreation Area and Grand Canyon National Park in the summer of 2008. They found that "mercury and selenium concentrations in minnows and invertebrates exceeded dietary fish and wildlife toxicity thresholds."
— Clean Air Plus (@cleanairplus) August 25, 2015
Though researchers point out that the number of samples was relatively low, bigger trout did not seem to be as affected.
“The good news is that concentrations of mercury in rainbow trout were very low in the popular Glen Canyon sport fishery, and all of the large rainbow trout analyzed from the Grand Canyon were also well below the risk thresholds for humans,” said co-author of the study Dr. Ted Kennedy.
This made for some surprising findings because "biomagnification usually leads to large fish having higher concentrations of mercury than small fish," says the researchers. "But we found the opposite pattern, where small, three-inch rainbow trout in the Grand Canyon had higher concentrations than the larger rainbow trout that anglers target." Why this happened has to do with the unique ecology of the Grand Canyon.
"Insect food sources for fish are quite limited in the Colorado River below Glen Canyon Dam, most likely due to temperature and flow regimes of the regulated river," Kennedy told The Arizona Daily Sun. "While smaller fish can satisfy their caloric needs by eating just insects, there aren’t enough of the invertebrates to make up the entire diet of larger fish, forcing them to feed on other less calorie-dense organic matter like algae."
But one of those insects, the black fly—a major food source for trout—is also a prime source of mercury contamination because it consumes a kind of algae that contains large amounts of a bioavailable form of mercury. “We think [the mercury] is getting picked up by that algae in Lake Powell and exported into Grand Canyon,” Kennedy said.
Another interesting finding was that the fish they sampled had none of the deformities often associated with mercury poisoning.
"That finding is evidence of a well-documented relationship between selenium and mercury whereby, in the right concentrations, selenium protects animals from mercury toxicity," Kennedy said. “If both of these things are at high levels together, it can mitigate effects of having just one of them in a high concentration.”
The researchers believe most of the mercury isn't coming from Lake Powell, though. They blame airborne transport and deposition for most of the mercury pollution in the Grand Canyon. This is a common way for remote ecosystems to become contaminated, says the USGS team. As for the selenium, they believe pollution from upstream sources is the culprit. "Irrigation of selenium-rich soils in the upper Colorado River basin contributes much of the selenium that is present in the Colorado River in Grand Canyon," say researchers.
Though environmental groups have honed in on the Navajo Generating Station and other coal-fired power plants around Lake Powell for their mercury pollution, David Gay of the National Atmospheric Deposition Program, points out "Linking mercury contamination in Lake Powell, or in the Colorado River Basin, to specific sources is difficult because it remains in the atmosphere for up to six months after it is initially emitted. That’s long enough for mercury emitted in one place to waft up into the atmosphere and then get carried hundreds or thousands of miles." He points to studies which show that mercury pollution in the area can come from as far away as California and even Asia.
“Mercury is a global pollutant,” Gay said. “Everybody is in it together.”
No human consumption advisories have been put in place yet, but researchers plan to do further studies to assess the potential risks to humans that may consume fish from this area. Selenium and mercury exposure has been linked to lower reproductive success, growth, and survival of fish and wildlife, say the researchers.
Experts warn people of all ages, but in particular pregnant women and children, to monitor their seafood intake due to high levels of mercury in some species. Consumer Reports even found that the U.S. Food and Drug Administration was advising people to consume fish at levels for which its own data indicated elevated risks. And last year, consumer protection and environmental advocates sued the U.S. Food and Drug Administration for failing to give consumers clear, accurate and accessible information about toxic mercury in the seafood they eat.
YOU MIGHT ALSO LIKE
EcoWatch Daily Newsletter
When Europeans first arrived in North America, Atlantic puffins were common on islands in the Gulf of Maine. But hunters killed many of the birds for food or for feathers to adorn ladies' hats. By the 1800s, the population in Maine had plummeted.
- Experts Recommend Halving Global Fishing for Crucial Prey Species ›
- US Court Upholds Ruling on Vast Marine Monument Established by ... ›
A "major" natural gas explosion killed two people and seriously injured at least seven in Baltimore, Maryland Monday morning.
- Fatal Natural Gas Explosion Rocks Durham, NC - EcoWatch ›
- Gas Explosion Rips Through Maryland Office & Shopping Complex ... ›
Nearly 900 people across the U.S. and Canada have been sickened by salmonella linked to onions distributed by Thomson International, the The New York Times reported.
- Meat Producers Issue Massive Recalls after Salmonella, Listeria ... ›
- Salmonella Outbreaks Could Worsen with Decreased Poultry ... ›
- Major Salmonella Outbreak Exacerbated by Government Shutdown ... ›
In the coming days, the U.S. Environmental Protection Agency (EPA) is expected to use its power to roll back yet another Obama-era environmental protection meant to curb air pollution and slow the climate crisis.
- Permian Basin Methane Emissions Found to Be More Than 2x ... ›
- Oil and Gas Operations Release 60 Percent More Methane than ... ›
- 'Extraordinarily Harmful' Trump Rule Would Gut Restrictions on ... ›
- Exxon Now Wants to Write the Rules for Regulating Methane ... ›
By Alex Kirby
The temperature of the Arctic matters to the entire world: it helps to keep the global climate fairly cool. Scientists now say that by 2035 there could be an end to Arctic sea ice.
Melt Ponds Crucial<p>"The prospect of loss of sea ice by 2035 should really be focusing all our minds on achieving a low-carbon world as soon as humanly feasible."</p><p><a href="http://www.reading.ac.uk/search/search-staff-details.aspx?id=10813" target="_blank">Dr. David Schroeder from the University of Reading</a>, UK, who co-led the implementation of the melt pond scheme in the climate model, says, "This shows just how important sea ice processes like melt ponds are in the Arctic, and why it is crucial that they are incorporated into climate models."</p><p>The extent of the areas <a href="https://nsidc.org/cryosphere/seaice/characteristics/formation.html" target="_blank">sea ice</a> covers varies between summer and winter. If more solar energy is absorbed at the surface, and temperatures rise further, a cycle of warming and melting occurs during summer months.</p><p>When the ice forms, the ocean water beneath becomes saltier and denser than the surrounding ocean. Saltier water sinks and moves along the ocean bottom towards the equator, while warm water from mid-depths to the surface travels from the equator towards the poles.</p><p>Scientists refer to this process as the ocean's global "conveyor-belt." Changes to the volume of sea ice can disrupt normal ocean circulation, with consequences for global climate. </p>
- Strongest, Oldest Arctic Sea Ice Breaks Up for First Time on Record ... ›
- Arctic Sea Ice Levels Hit Record Low After Unusually Warm January ... ›
- Why California Droughts Could Increase Due to Arctic Sea Ice Loss ... ›
Russia's Health Ministry has given regulatory approval for the world's first COVID-19 vaccine after less than two months of human testing, President Vladimir Putin said on Tuesday.
Putin's Daughter Among Vaccinated<p>The Russian leader also said that one of his daughters has already been inoculated and is feeling well.</p><p>"One of my daughters got vaccinated, so in this sense, she took part in the testing," Putin said.</p><p>After the first vaccine shot, his daughter experienced a slight fever, 38 degrees Celsius (100.4°F). Her temperature came down to just slightly above normal the next day. </p><p>"After the second shot, she had a slight fever again, and then everything was fine. She is feeling well and has a high antibody count," Putin said. </p><p>He didn't specify which of his two daughters, Maria or Katerina, received the vaccine.</p><p>Russian health authorities have said that medical workers, teachers and other risk groups will be the first to receive shots of the vaccine.</p>
Years of Work Reduced to Weeks<p>Russia is the first country to register a COVID-19 vaccine. As <a href="https://www.dw.com/en/germany-coronavirus-vaccine-may-only-be-available-in-mid-2021/a-54362065" target="_blank">countries worldwide race to produce the first vaccine</a>, health experts warn that speed and national pride could compromise safety.</p><p>Scientists in Russia and abroad have questioned Moscow's decision to register the vaccine before Phase 3 trials that normally last for months and involve thousands of people, but Putin emphasized that the vaccine underwent the necessary trials and that vaccination will be voluntary.</p><p>Russian officials have said that large-scale production of the vaccine will begin in September, and mass vaccination may start as early as October.</p><p>Philippine President Rodrigo Duterte, meanwhile, has <a href="https://www.dw.com/en/philippines-duterte-volunteers-to-be-putins-russian-coronavirus-vaccine-guinea-pig/a-54523030" target="_blank">lauded Russia's efforts in developing the vaccine</a> and said that the Philippines is ready to work with Moscow on vaccine trials, supply and production. Duterte volunteered to "be the first they can experiment on."</p><p>"I will tell President Putin that I have huge trust in your studies in combating COVID and I believe that the vaccine that you have produced is really good for humanity," Duterte said, adding that he thinks Russia's vaccine will be ready for the Philippines by December.</p>
- Pfizer Coronavirus Vaccine Enters Phase 2 and 3 Clinical Trials ... ›
- Trump Administration Buys up Nearly All the World's Supply of ... ›
- First Trial of Moderna's Coronavirus Vaccine Produces Immune ... ›
A powerful series of thunderstorms roared across the Midwest on Monday, downing trees, damaging structures and knocking out power to more than a million people.