USGS claims that mercury and selenium are accumulating in the Colorado River

A study conducted by the U.S. Geological Survey (USGS) claims to have found “relatively high -compared with other large rivers” concentrations of mercury (Hg) and selenium (Se) in the food web along the Colorado River between Glen Canyon Dam and the Grand Canyon, The study was done in the summer of 2008, but curiously, results were just published in the journal Environmental Toxicology and Chemistry in August 2015. Perhaps they were taking advantage of publicity associated with the toxic spill from the Gold King mine in Colorado earlier this month.

USGS Hg Se study map

Some excerpts from the press release:

“The study, led by the U.S. Geological Survey, found that concentrations of mercury and selenium in Colorado River food webs of the Grand Canyon National Park, regularly exceeded risk thresholds for fish and wildlife. These risk thresholds indicate the concentrations of toxins in food that could be harmful if eaten by fish, wildlife and humans. These findings add to a growing body of research demonstrating that remote ecosystems are vulnerable to long-range transport and bioaccumulation of contaminants.”

“The study examined food webs at six sites along 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. The researchers found that mercury and selenium concentrations in minnows and invertebrates exceeded dietary fish and wildlife toxicity thresholds.”

“Although the number of samples was relatively low, mercury levels in rainbow trout, the most common species harvested by anglers in the study area, were below the EPA threshold that would trigger advisories for human consumption.”

See full paper: http://onlinelibrary.wiley.com/doi/10.1002/etc.3077/epdf

From the paper:

“Sampling occurred from 12 to 28 June 2008. At each site, we collected representative basal resources (organic matter and primary producers), macroinvertebrates, and fishes. Basal resources included fine benthic organic matter, seston (suspended organic matter), epilithon (benthic biofilm), attached algae (Cladophora sp.), and epiphyton (diatoms attached to Cladophora). We collected fine benthic organic matter from sandy depositional habitats using a Ponar dredge (0.052 m2 ) deployed from a boat.”

As far as I can determine, the study analyzed fewer than 25 samples of each group along 250 miles of river. That is indeed a very low number upon which to form conclusions.

“In the present study we found no significant differences in Hg and Se accumulation among sites throughout the Grand Canyon.”

“There is a well-documented antagonistic interaction between Se and Hg, whereby Se protects animals from Hg toxicity when Hg:Se molar ratios are approximately 1 or less. The Hg:Se molar ratios were typically much lower than 1 in the present study, ranging from 0.04 (rainbow trout) to 0.38 (fathead minnow) among fish species. Assuming that Se and Hg in prey are equally transferred to consumers, this large excess of Se in this system suggests that the risks of Hg toxicity could be considerably lower than the Hg wildlife risk values alone would indicate.”

From the press release:

“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 one of the study authors.

“We also found some surprising patterns of mercury in rainbow trout in the Grand Canyon. Biomagnification usually leads to large fish having higher concentrations of mercury than small fish. But we found the opposite pattern, where small, 3-inch rainbow trout in the Grand Canyon had higher concentrations than the larger rainbow trout that anglers target.”

Regarding mercury: “Airborne transport and deposition — with much of it coming from outside the country — is most commonly identified as the mechanism for contaminant introduction to remote ecosystems, and this is a potential pathway for mercury entering the Grand Canyon food web.” Selenium is derived from “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.”

The paper abstract notes that “consistent longitudinal patterns in Hg or Se concentrations relative to the dam were lacking.” That would seem to cast in doubt the proposed source of selenium from upstream irrigation of agricultural land. The “relatively high” concentrations they were talking about in fish are 0.17–1.59 ppm Hg and 1.35–2.65 ppm Se.


Wind turbines versus wildlife

In our quest to find greener sources of energy, what at first seems like a good idea leads to some not-so-green unintended consequences. Such is the case with wind turbines and wind farms.

In an article in The Spectator (a British publication, not the American Spectator), zoologist Clive Hambler notes:

“Wind turbines only last for ‘half as long as previously thought’, according to a new study. But even in their short life spans, those turbines can do a lot of damage. Wind farms are devastating populations of rare birds and bats across the world, driving some to the point of extinction. Most environmentalists just don’t want to know. Because they’re so desperate to believe in renewable energy, they’re in a state of denial. But the evidence suggests that, this century at least, renewables pose a far greater threat to wildlife than climate change.”

“Every year in Spain alone — according to research by the conservation group SEO/Birdlife — between 6 and 18 million birds and bats are killed by wind farms. They kill roughly twice as many bats as birds. This breaks down as approximately 110–330 birds per turbine per year and 200–670 bats per year. And these figures may be conservative if you compare them to statistics published in December 2002 by the California Energy Commission: ‘In a summary of avian impacts at wind turbines by Benner et al (1993) bird deaths per turbine per year were as high as 309 in Germany and 895 in Sweden.’”

This danger to birds and bats is not confined to Europe. An article in the Washington Times by Paul Driessen notes:

“The U.S. Fish and Wildlife Service (FWS) and American Bird Conservancy say wind turbines kill 440,000 bald and golden eagles, hawks, falcons, owls, cranes, egrets, geese and other birds every year in the United States, along with countless insect-eating bats.

“New studies reveal that these appalling estimates are frightfully low and based on misleading or even fraudulent data. The horrific reality is that in the United States alone, “eco-friendly” wind turbines kill an estimated 13 million to 39 million birds and bats every year.”

In the recent “fiscal cliff” negotiations, it seems crony capitalism triumphed over good sense. Lobbying by the wind industry saved its subsidy, the Production Tax Credit, which was set to expire at the end of 2012. The “cliff” deal now extends that subsidy through 2013 thus costing American taxpayers $12 billion, and encouraging use of a very expensive, very unreliable, and to wildlife, a very lethal form of “green” energy production.

See also:

(human) Health Hazards of Wind Turbines

Electricity generated by wind power may raise temperatures and costs

Wind farms raise local and regional temperatures

Thorium, another alternative energy choice