Gold rush, mercury legacy: Small-scale mining for gold has produced long-lasting toxic pollution, from 1860s California to modern Peru — The Conversation


Artisanal small-scale gold mining polluted this stream and deforested sections of the Madre de Dios area of Peru.
Mario Tama/Getty Images

Jacqueline Gerson, Duke University; Austin Wadle, Duke University, and Jasmine Parham, Duke University

Gold is everywhere in modern life, from jewelry to electronics to smartphones. The global electronics industry alone uses 280 tons annually. And that demand keeps growing.

But most people know little about the environmental impacts of gold mining. About 15% of world gold production is from artisanal and small-scale mining in over 70 countries throughout Asia, Africa and South America. These operations employ 10 to 19 million workers. They often are poorly policed and weakly regulated.

Artisanal mining might sound quaint, but it is usually criminal activity and results in widespread environmental damage. It also is the largest source of mercury pollution in the world today, far exceeding other activities such as coal combustion and cement manufacturing. While mercury is an element that occurs naturally in the Earth’s crust, it has many toxic effects on humans and animals, even at very low exposure levels.

We have studied mercury pollution from artisanal gold mining for the past five years. The extraction methods that these operations use today are not drastically different from processes that miners employed in the California gold rush in the mid-1800s. Today we see history repeating itself in places like the Peruvian Amazon, where small-scale gold mining threatens to leave behind long-lasting social, economic and environmental consequences.

Mercury contamination from gold mining

Mercury has been used for centuries as an inexpensive and easy way to collect gold. The process begins when miners pump a mixture of water and sediment from a riverbed into a trough, where the sediment can be suspended into a slurry – a technique known as hydraulic mining.

Next they add mercury, which binds to the gold particles, forming an amalgam. Mercury is heavier than pure gold, so the balls of amalgam sink to the bottom of buckets or holding ponds where they can be collected. Finally, workers burn off the mercury – often with a hand torch or in a crude stove – leaving gold metal behind.

This process releases mercury to the environment in two forms. First, tailings, or waste material, can contaminate nearby land and aquatic ecosystems. Second, mercury vapor enters the atmosphere and can travel long distances before being deposited to land and water via rainfall or small dust particles.

In the environment, microbes can transform mercury into a more potent form known as methylmercury. Methylmercury can be taken up by bacteria, plankton and other microorganisms that are then consumed by fish and build up to dangerous concentrations in animals higher on the food chain.

When artisanal gold miners burn mercury, it is released into the atmosphere and can end up on land or in water. Mining tailings (solid waste) also deposit mercury onto land or into water. Microbes in the environment can convert mercury into methylmercury, which can be taken up by living organisms, including fish and people.
Arianna Agostini, Rand Alotaibi, Arabella Chen, Annie Lee, Fernanda Machicao, Melissa Marchese, CC BY-ND

Methylmercury is a potent neurotoxin that is harmful to humans and wildlife, such as endangered giant otters that feed high on the food web within these contaminated environments. It can cause severe central nervous system damage that results in sensory and motor deficits, as well as behavioral impairments such as difficulty swimming in aquatic animals and flying in birds.

A lasting legacy in California

During the U.S. gold rush, hydraulic mining operations in California completely denuded forested landscapes, altered the course of rivers, increased sedimentation that clogged river beds and lakes and released enormous amounts of mercury onto the landscape. California wildcat miners used an estimated 10 million pounds of mercury from the 1860s through the early 1900s. Most of it was released to the environment as tailings and mercury vapor.

Panning for gold in California, 1850.
Unknown/Wikipedia

A century later, water, soil and sediments in the Sierra Nevada region still have high concentrations of mercury and methylmercury, often exceeding thresholds set by the U.S. Environmental Protection Agency. Studies show that fish, birds and other organisms living near historically mined sites in California have high mercury concentrations in their bodies compared to those inhabiting nearby unmined landscapes. Extreme erosion on mountain slopes can continuously mobilize mercury deposited decades ago.

History repeats itself

Like men who traveled to California in 1849 hoping to strike it rich, today’s artisanal miners around the world are mainly low-skilled workers hoping to support themselves and their families.

In Peru, where we have studied this process, artisanal miners produce an estimated 35,000 to 40,000 pounds of gold per year. The industry offers an opportunity for upward mobility for substantial numbers of Peruvians, who generally migrate to mining sites from coastal and mountain towns.

As a result, gold rush towns have boomed over the past 20 years. The Inter-Oceanic Highway, which was completed in 2012 and runs from Brazil’s Atlantic coast to Peru’s Pacific coast, has connected these towns to larger cities and increased access to the Peruvian Amazon.

Producing a pound of gold requires about 6 pounds of mercury. Given that at least 50% of the mercury used in these operations is lost to the environment, we estimate that artisanal gold mining in Peru alone releases nearly 50,000 pounds of mercury annually.

Mining in this region is producing impacts that are strikingly similar to the hallmarks of the California gold rush. For example, miners in the Peruvian Amazon have cleared more than 250,000 acres of forest since 1984.

The Madre de Dios River, which runs through a zone that has seen substantial mining, will likely continue to erode the landscape, carrying mercury-laden particles downstream. Long-lasting mercury contamination in this region threatens the highest biodiversity on the planet and many indigenous communities.

Comparison of landscape change from gold mining during the California gold rush (left) and modern artisanal mining in Peru (right).
Bancroft Library, UC Berkeley (left); Arabella Chen (right)

Gold mining in 19th-century California sparked a wave of western migration and helped drive settlement of what we now refer to as the western United States at a time when mining and environmental pollution were unregulated. Today, use of mercury in artisanal gold mining is regulated by the 2013 Minamata Convention on Mercury, which has been signed by 128 countries – including Peru. Yet there is little on-the-ground regulation in most countries. Nor have governments addressed legacy pollution and deforestation from gold mining.

Illegal artisanal gold mining is a major source of income for local communities in places like the Madre de Dios region of Peru. As long as people all over the world continue to demand more gold, we believe that they are just as responsible as miners and local policymakers for the environmental degradation gold mining causes.

[You’re smart and curious about the world. So are The Conversation’s authors and editors. You can get our highlights each weekend.]The Conversation

Jacqueline Gerson, Ph.D. Candidate in Ecology, Duke University; Austin Wadle, Ph.D. Student in Civil and Environmental Engineering, Duke University, and Jasmine Parham, Ph.D. Student in Biology, Duke University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Food webs determine the fate of mercury pollution in the #ColoradoRiver, #GrandCanyon: Floods can shift animal populations, altering mercury passed to fish and other wildlife — Cary Institute of Ecosystem Studies #COriver

Glen Canyon Dam

Here’s the release from the Cary Institute of Ecosystem Studies:

In the Grand Canyon reach of the Colorado River, two species play an outsized role in the fate of mercury in the aquatic ecosystem, and their numbers are altered by flood events. So reports new research, published in Science Advances, that is among the first to meld ecotoxicology and ecosystem ecology to trace how mercury flows through aquatic food webs and then spreads to land.

Mercury is an environmental contaminant that occurs in ecosystems globally. In its organic form, it is a potent neurotoxin that can harm people and wildlife. Mercury accumulation in animals and how it magnifies along food chains is well studied. Less well understood are the pathways mercury takes through food webs to reach top predators, such as fish and birds, and how those pathways might change after large ecosystem disturbances, such as floods.

Emma Rosi is an aquatic ecologist at Cary Institute of Ecosystem Studies and co-lead author on the paper. She explains, “By combining data on mercury concentrations in aquatic life with well-studied food webs, we were able to reveal how mercury moves through an ecosystem. We found that flooding and an invasive species both influenced the flow of this contaminant of global concern.”

Blackflies are an important food source for rainbow trout, a popular species among recreational anglers in the Colorado River. Credit: US Geological Survey/Freshwaters Illustrated-Dave Herasimtschuk via Cary Institute of Ecosystem Studies.

The traits of organisms living in an ecosystem – their physiology, what they eat, and what eats them – determine contaminant movement and exposure. These factors have rarely been included in models of contaminant flux and fate. “Pairing contaminant concentrations and highly detailed food webs has the potential to improve the management of contaminants in ecosystems,” Rosi notes.

To study these pathways, the research team developed mercury-based food webs for six sites spanning 225 miles of the Colorado River, extending downstream from the Glen Canyon Dam in Grand Canyon National Park. Food web sampling took place seasonally over two years. At each site, they measured algae, invertebrates, and fish to determine who was eating what – and what that meant for mercury exposure at each level of the food web.

Insects (blackflies and midges) and invasive New Zealand mudsnails were the dominant invertebrates in the river. These animals play a vital role in moving energy and contaminants from the bottom of the food web to fish predators at the top. Fish included native Bluehead Sucker, Flannelmouth Sucker, Speckled Dace, and Humpback Chub, as well as non-native species such as Common Carp, Fathead Minnow, and Rainbow Trout.

The stomach contents of invertebrates and fish were assessed to identify what they ate and in what amounts. Algae, detritus, and animals were analyzed for mercury concentrations and, combined with the diet data, the team estimated the amount of mercury that animals were consuming throughout the year.

Food web complexity varied across the study sites. Just below the Glen Canyon Dam, food webs were simple with few species and food web connections. Further downstream, food webs had higher species diversity and more connections. Across the study sites, regardless of food web complexity, relatively few species were key players in the movement of mercury.

Algae and tiny particles of detritus were the source of 80% of mercury flowing to invertebrates.
In sites closest to the dam, invasive mudsnails dominated the food webs. Trout were the only fish in this part of the river, and they are unable to digest mudsnails. Mercury accumulated by the snails did not move up the food chain. Because the snails are fully aquatic, mercury cycled back into the river’s detrital food web when they died.

Blackfly larvae were the source of 56-80% of the mercury flowing to fish. Blackflies are preferred prey for fish, such as Rainbow Trout, and blackflies had higher mercury contaminations compared to other invertebrates. Blackflies that escape predation and emerge from the river as flying adults move mercury from the river to land. This can expose terrestrial predators, such as birds and bats, to mercury that started out in the river.

Blackflies have the highest mercury concentration among Grand Canyon invertebrates. As larvae (top), they are important fish prey. When blackflies emerge as adults, they transfer mercury to birds, bats, lizards, and spiders on land. New Zealand mudsnails (bottom) contain mercury but are indigestible to trout; when fish eat them, they pass through unscathed. When the snails die and decompose, the mercury they contain is released back into the river. Credit: US Geological Survey/Freshwaters Illustrated-Dave Herasimtschuk via the Cary Institute for Ecosystem Studies.

The amount of mercury that blackflies moved to land was dependent on the number of hungry fish in any part of the river. At some sites, fish ate nearly 100% of the blackfly larvae, leaving few left to emerge. At other sites, there were a lot more blackflies than the fish could eat. When these blackflies emerged as adults, the mercury inside them hitched a ride to terrestrial food webs along the river.

One year into sampling, the study sites were flooded as part of a planned dam release. The team was able to explore the effects of the flood on mercury movement in the food webs. At sites near the dam, the flood washed away large numbers of New Zealand mudsnails and led to a boom in blackfly populations. With the rise in blackflies, more mercury flowed to trout. Because trout gobbled up nearly all the blackflies in their larval form, very little of the mercury accumulated in these abundant insects was transported to land by the flying adults.

Rosi explains, “Changes to the animal populations in an ecosystem will impact how mercury moves through a food web. This was especially apparent at sites where flooding changed the proportion of blackflies relative to fish. Flooding dramatically altered mercury pathways in the simple tailwater food web near the dam, but not in the more complex food webs downstream.”

“Invasive species and dams are common in rivers globally, and both factors were at play in the Grand Canyon reach of the Colorado River.” Rosi says. “We found that flooding changed the species present at our study sites, and mercury flow changed with those shifts.”

“Understanding the factors that control the movement of mercury through food webs can help resource managers protect ecosystems that are susceptible to mercury pollution,” says David Walters, USGS scientist and co-lead author of the study.

Rosi concludes, “This study is exciting because it sheds light on the depth of understanding we can achieve when we merge ecological and ecotoxicological thinking. Species traits, animal populations, predator-prey interactions, and disturbance can all influence the movement of contaminants in the environment. Understanding the complex interplay of these factors can improve risk management of animal exposures in the environment.”

Citation: Read the full study: https://advances.sciencemag.org/content/advances/6/20/eaaz4880.full.pdf

This work was funded by the USGS Cooperative 644 Agreement 05WRAG0055 and the USGS Environmental Health Contaminant Biology Program.

Investigators

D. M. Walters – US Geological Survey, Columbia Environmental Research Center

W.F. Cross – Department of Ecology, Montana State University

T.A. Kennedy – US Geological Survey, Grand Canyon Monitoring and Research Center

C.V. Baxter – Department of Biological Sciences, Idaho State University

R.O. Hall, Jr. – Flathead Lake Biological Station, University of Montana

E.J. Rosi – Cary Institute of Ecosystem Studies

EPA guts rule credited with cleaning up coal-plant toxic air — Associated Press #ShameOnYou

Mercury in Colorado graphic via The Denver Post

From The Associated Press (Ellen Knickmeyer):

The Trump administration on Thursday gutted an Obama-era rule that compelled the country’s coal plants to cut back emissions of mercury and other human health hazards, a move designed to limit future regulation of air pollutants from coal- and oil-fired power plants.

Environmental Protection Agency chief Andrew Wheeler said the rollback was reversing what he depicted as regulatory overreach by the Obama administration. “We have put in place an honest accounting method that balances” the cost to utilities with public safety, he said.

Wheeler is a former coal lobbyist whose previous clients have gotten many of the regulatory rollbacks they sought from the Trump administration.

Environmental and public health groups and Democratic lawmakers faulted the administration for pressing forward with a series of rollbacks easing pollution rules for industry — in the final six months of President Donald Trump’s current term — while the coronavirus pandemic rivets the world’s attention.

With rollbacks on air pollution protections, the “EPA is all but ensuring that higher levels of harmful air pollution will make it harder for people to recover in the long run” from the disease caused by the coronavirus, given the lasting harm the illness does to victims hearts and lungs, said Delaware Sen. Tom Carper, the senior Democrat on the Senate Environment and Public Works Committee.

The EPA move leaves in place standards for emissions of mercury, which damages the developing brains of children and has has been linked to a series of other ailments. But the changes greatly reduce the health benefits that regulators can consider in crafting futures rules for power plant emissions. That undermines the 2011 mercury rule and limits regulators’ ability to tackle the range of soot, heavy metals, toxic gases and other hazards from fossil fuel power plants.

The Trump administration contends the mercury cleanup was not “appropriate and necessary,” a legal benchmark under the country’s landmark Clean Air Act.

The Obama rule led to what electric utilities say was an $18 billion cleanup of mercury and other toxins from the smokestacks of coal-fired power plants. EPA staffers’ own analysis said the rule curbed mercury’s devastating neurological damage to children and prevented thousands of premature deaths annually, among other public health benefits.

From The Deseret News (Amy Joi O’Donoghue):

Controversy over pollutants from coal-fired power plants moved to a higher level Thursday after the U.S. Environmental Protection Agency announced it had revised a cost benefit analysis over the impacts of mercury emissions regulations imposed during the Obama era.

The federal agency said the restrictions on mercury emissions through technology controls were not justified, backing a 2015 U.S. Supreme Court decision that directed the agency to complete another review.

EPA Administrator Andrew Wheeler, in a teleconference, said the 2012 Obama-era rule remains in place and no additional mercury emissions will happen due to the revised analysis.

He added that critics of the Thursday announcement are either purposefully misreading the revisions or don’t understand…

In a major victory for the energy industry, the U.S. Supreme Court ruled against federal regulators’ attempts to curb mercury emissions from power plants in 2015, saying the government wrongly failed to take cost into consideration.

The 5-4 decision overturned the landmark rule, which was the first attempt by the EPA to curb mercury and other pollutants from coal-fired power plants.

Michigan’s lawsuit against the regulation was joined by 21 other GOP-led states, including Utah, in a fight to get it tossed.

The new “supplemental cost finding” announced by the federal agency found compliance costs for mercury emissions at power plants ranging from $7.4 billion to $9.6 billion annually due to the rule and the benefits in terms of reduction in costs such as health care to be around $6 million.

Wheeler added that the Obama administration’s approach was that any new regulation could be justified, regardless of the cost…

Moms Clean Air Force issued a statement expressing its outrage over the move.

“While America suffers devastating public health impacts of the coronavirus outbreak — a lethal respiratory pandemic — Andrew Wheeler and the Trump administration continue their cynical campaign to protect industrial polluters and undermine lifesaving pollution protections,” said co-founder Dominique Browning.

The organization added that the EPA is gambling with the health of children by giving any sort of nod to coal-fired power plants.

Wheeler dismissed any criticism, again reiterating the revision released Thursday was the result of a court-directed action to correct flaws of a previous administration’s conclusions over costs and benefits.

Down ‘The River Of Lost Souls’ With Jonathan Thompson — Colorado Public Radio

From Colorado Public Radio (Nathan Heffel). Click through to listen to the interview:

A new book puts the Gold King Mine spill within the long history of mining and pollution in Southwest Colorado.

Jonathan Thompson will be at the Book Bar tonight. I wonder if Denver is a bit of a shock to his system even though he’s a sixth-generation Coloradan?

I am so happy to finally get to finally meet Jonathan. His new book, River of Lost Souls, is an important read. Understanding the industrialization of our state over the years will help us chart a less destructive course.

I loved the passages where Jonathan reminisces about spending time around the Four Corners and in the San Juans. He transports you to those times in your life spent next to the river or exploring what sights the land has to offer. He connects you to the Four Corners in a way that only a son of the San Juans could.

Cement Creek aerial photo — Jonathan Thompson via Twitter

The Animas River Stakeholders Group is bringing on Boston-based InnoCentive to help solve the acid mine drainage problem around Silverton

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From The Durango Herald (Dale Rodebaugh):

The problem will be turned over to InnoCentive, a Boston firm that has 260,000 individual “solvers” eager to tackle challenges in chemistry, food production, business, engineering, information technology and physical and life sciences.

Members of the stakeholder steering committee Wednesday devised a tentative agenda outlining problems they want to solve. The group will meet again within a month to refine its proposal.

“InnoCentive has all these problem-solvers who think out of the box and check in looking for a challenge,” committee member Bill Simon said. “In the end, the solution is ours to use.”

The problem-solver and InnoCentive get paid, and it isn’t cheap, Simon said. But acidic drainage from mines is a worldwide problem, which could win financial support from mining interests, environmental groups and government agencies…

Today, four mines – Sunnyside, Mogul, Gold King No. 7 and Red & Bonita – send up to 800 gallons a minute of iron, zinc, cadmium, copper, lead, mercury, manganese and aluminum into Cement Creek, a tributary to the Animas River at Silverton.

The stream is so toxic that biologists think the water never sustained aquatic life.

More Animas River Watershed coverage here.

New EPA rules for coal-fired electrical generation plants may reduce mercury in waterways

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From the Colorado News Connection (Kathleen Ryan) via The Durango Herald:

David Ellenberger, Rocky Mountain regional coordinator with the National Wildlife Federation, says the scrubbers will reduce mercury pollution by at least 91 percent. He adds that cleaner air translates into cleaner water for Colorado’s lakes and rivers. “It’s absolutely a huge step forward in protecting public health, our children and our wildlife from these aspects of this hazardous air pollution.”[…]

Elemental mercury finds its way into lakes and reservoirs from prevailing winds, precipitation and runoff. It is converted to toxic methylmercury by microorganisms, the bottom of the food chain. Arsenic and selenium also contaminate fish but to a lesser degree than mercury…

Some utilities criticize the new rules as too onerous, especially as they pertain to older coal plants that may not be suitable for scrubber retrofits. The EPA estimates meeting the standards will cost utilities about $11 million nationwide. Ellenberger claims the savings in health-care costs more than make up for the expense. “The EPA estimates that for every dollar the utilities are about to spend on pollution controls at their coal-fired power plants, public health is going to benefit by about $13, which is pretty impressive,” he said.

More mercury pollution coverage here.

San Juan Mountains: Research into high mercury levels

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From The Durango Herald (Dale Rodebaugh):

“In 2007 we began to study mercury because very little was known about its presence in Southwest Colorado other than that reservoirs had fish-consumption advisories, and that precipitation sometimes deposited heavy concentrations of mercury at Mesa Verde National Park,” former institute director Koren Nydick said last week by telephone.

As result of mercury accumulation in fish, the state of Colorado has posted advisories at McPhee, Totten, Narraguinnep and Vallecito reservoirs and Najavo Lake cautioning about consumption of fish from those waters.

Kelly Palmer, a Bureau of Land Management hydrologist, said as a result of the Mountain Studies Institute pilot study at Molas Pass, the San Juan National Forest in 2009 initiated a long-term mercury-monitoring program there.

“It appears the levels of mercury are notable,” Palmer said last week…

Analysis of mercury and weather data collected from 2002 to 2008 at Mesa Verde points to coal-fired power plants in New Mexico as potential sources of mercury. Analysis of pollution components as well as potential sources and storm pathways support the theory, Nydick said.

But they don’t pinpoint specific sources and don’t definitely rule out the possibility that storms were carrying pollution from elsewhere when they passed over the New Mexico plants…

In June 2009, researchers from MSI and other agencies spent a day in Mancos Canyon trapping and releasing songbirds after testing their blood for mercury. They also collected crayfish, spiders, sow bugs, cicadas and centipedes and planned to return to electro-shock fish for testing.

“Wetland-dependent songbirds were chosen for study, in addition to fish and crayfish, because research shows they can accumulate methyl mercury,” Nydick said at the time. “It appears they accumulate methyl mercury from prey such as spiders that are a link between the aquatic and terrestrial food webs. That is why we collect invertebrates, soil and dead foliage to analyze for mercury, too.”

More mercury pollution coverage here and here.

Energy policy — coal: Mercury emissions from coal-fired power plants rise recently across the U.S.

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From The Denver Post (Renee Schoof):

Many coal- fired power plants lack widely available pollution controls for the highly toxic metal mercury, and mercury emissions recently increased at more than half of the country’s 50 largest mercury-emitting power plants, according to a report released Wednesday. Five of the 10 plants with the highest amount of mercury emitted are in Texas, according to the nonpartisan Environmental Integrity Project. Plants in Georgia, Missouri, Alabama, Pennsylvania and Michigan also are in the top 10. The report, which used the most recent data available from the U.S. Environmental Protection Agency, found that mercury emissions increased at 27 of the top 50 plants from 2007 to 2008. Overall, power- plant emissions of mercury decreased 4.7 percent in that period, but that amount was far less than what would be possible with available emissions controls, the report said. No Colorado plants were among the top 50 cited.

More coal coverage here and here.

Colorado to release 303d list on Tuesday

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From The Grand Junction Daily Sentinel (Emily Anderson):

The Colorado Department of Public Health and Environment on Tuesday will adopt a lengthy list (pdf) of Colorado waters it has deemed impaired.

Despite the city of Grand Junction’s attempts to reverse the decision, the list likely will include Juniata Reservoir on Grand Mesa, which provides a majority of Grand Junction’s drinking water. The city temporarily closed the reservoir to visitors and fishermen before opening it again in late February, when the Health Department told the city the closure would not get the reservoir off the impaired-waters list…

Steve Gunderson, director of the state Health Department’s water-quality division, said most items on the list have water-contamination problems, but some areas get listed just for having active fish-consumption advisories, such as the one Juniata has…

City Attorney John Shaver said the city likely will offer suggestions to the Health Department staff about changing the methodology for listing bodies of water on the impaired list so the list would reflect water, and not fish, contamination.

More mercury pollution coverage here and here.

Juniata Reservoir fish consumption advisory due to mercury

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From the Grand Junction Daily Sentinel (Emily Anderson):

The statement adds that the city “is extremely concerned about public misinterpretations of the potential listing of its pristine terminal drinking water source reservoir as being impaired by mercury,” because the reservoir is at risk for addition to a state list of bodies of water that don’t meet water quality standards. The reservoir was adopted as a “high priority” on the list when it received preliminary approval from the state Water Quality Control Commission on Feb. 8. Although most bodies of water on the list are included because of water contamination, Juniata Reservoir and a few other bodies were included solely for having a fish-consumption advisory, according to Steve Gunderson, director of the Colorado Department of Public Health and Environment’s water quality division. “The levels of mercury in the water, you wouldn’t be able to detect them,” Gunderson said. “You’re talking extremely low mercury, but it accumulates in the fish. Gunderson said state health officials are meeting with city officials about taking Juniata off the list if they can get rid of all contaminated fish or isolate the reservoir. The final list will not be adopted until March 9.

More infrastructure coverage here.

USGS: Mercury in fish widespread

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Here’s the abstract from the study:

Mercury (Hg) was examined in top-predator fish, bed sediment, and water from streams that spanned regional and national gradients of Hg source strength and other factors thought to influence methylmercury (MeHg) bioaccumulation. Sampled settings include stream basins that were agricultural, urbanized, undeveloped (forested, grassland, shrubland, and wetland land cover), and mined (for gold and Hg). Each site was sampled one time during seasonal low flow. Predator fish were targeted for collection, and composited samples of fish (primarily skin-off fillets) were analyzed for total Hg (THg), as most of the Hg found in fish tissue (95–99 percent) is MeHg. Samples of bed sediment and stream water were analyzed for THg, MeHg, and characteristics thought to affect Hg methylation, such as loss-on-ignition (LOI, a measure of organic matter content) and acid-volatile sulfide in bed sediment, and pH, dissolved organic carbon (DOC), and dissolved sulfate in water. Fish-Hg concentrations at 27 percent of sampled sites exceeded the U.S. Environmental Protection Agency human-health criterion of 0.3 micrograms per gram wet weight. Exceedances were geographically widespread, although the study design targeted specific sites and fish species and sizes, so results do not represent a true nationwide percentage of exceedances. The highest THg concentrations in fish were from blackwater coastal-plain streams draining forests or wetlands in the eastern and southeastern United States, as well as from streams draining gold- or Hg-mined basins in the western United States (1.80 and 1.95 micrograms THg per gram wet weight, respectively). For unmined basins, length-normalized Hg concentrations in largemouth bass were significantly higher in fish from predominantly undeveloped or mixed-land-use basins compared to urban basins. Hg concentrations in largemouth bass from unmined basins were correlated positively with basin percentages of evergreen forest and also woody wetland, especially with increasing proximity of these two land-cover types to the sampling site; this underscores the greater likelihood for Hg bioaccumulation to occur in these types of settings. Increasing concentrations of MeHg in unfiltered stream water, and of bed-sediment MeHg normalized by LOI, and decreasing pH and dissolved sulfate were also important in explaining increasing Hg concentrations in largemouth bass. MeHg concentrations in bed sediment correlated positively with THg, LOI, and acid-volatile sulfide. Concentrations of MeHg in water correlated positively with DOC, ultraviolet absorbance, and THg in water, the percentage of MeHg in bed sediment, and the percentage of wetland in the basin.

More mecury pollution coverage here and here.

Silverton: New mercury monitoring gear

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From The Durango Herald (Dale Rodebaugh):

The monitor – atop an 8-foot-high platform – consists of a glass jar enclosed in a metal box, the roof of which retracts when a sensor detects precipitation. The sensor notes when it stops raining or snowing and the roof slides back to protect the jar from contaminants. Hydrochloric acid in the jar binds with the mercury to prevent it from evaporating. The jars are collected weekly and sent to Frontier GeoSciences in Seattle for analysis.

“After the mercury study by the Mountain Studies Institute in 2007 and 2008, we felt we should take a closer look,” [Bureau of Land Management hydrologist Kelly Palmer] said. “After all, we’re charged with protecting the pristine quality of Class 1 airsheds such as Mesa Verde and the Weminuche Wilderness.” Scientists suspect the main source of mercury is power plants in the Four Corners.

Over time, data on weekly and total mercury accumulation will give scientists a good picture of the situation in the San Juan Mountains and allow them to compare results with 120 similar sites in the country, including two in Alaska, Palmer said…

Later this summer, the Environmental Protection Agency will install an apparatus next to the mercury monitor to measure gaseous mercury, an airborne form of mercury that reacts rapidly with precipitation or particulate matter and can be deposited in wet or dry form. Roger Claybrooke, a meteorologist with the NADP, and a half-dozen BLM and Forest Service seasonal employees did the hands-on work June 30. In addition to installing the mercury monitor, they replaced an old rain gauge on a separate platform a few yards away. A third platform holds a monitor that measures sulfur, nitrogen and organic content in precipitation. The Claybrooke team also wired the instruments on the three stations to talk to one another. The rain gauge data should correlate with that of the mercury monitor on the amount of precipitation and when it fell.

More Coyote Gulch coverage here and here.

Mercury pollution: Many questions some answers

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Here’s a look at mercury pollution in Colorado, from Mark Jaffe writing for the Denver Post. From the article:

The heavy metal, however, isn’t found in fish in all lakes or all species in tainted lakes — a phenomenon in Colorado and in other parts of the country. So scientists are now trying to unravel the mystery of why it pops up in Carter Lake walleye, but not those in Chatfield Reservoir. “We’ve got some very hot fish in some, but not in all our reservoirs,” said Nicole Vieira, a state Division of Wildlife aquatic toxicologist. “If we can figure out what is at work, we might be able to manage the fish stocks to reduce mercury,” she said. At the same time, Colorado has issued regulations requiring mercury air emissions from power plants — a prime source of the pollutant — be cut 90 percent by 2018…

A dusting of mercury is falling into lakes and rivers all across the country — the Environmental Protection Agency estimates more than 112 tons of mercury emissions was generated in 2005. Among the largest sources are power plants, cement kilns, refineries and commercial boilers, according to the EPA. But the inorganic mercury coming out of those smokestacks would just sit on a lake bottom if not for bacteria that turn it into methylmercury — which animals along the food chain can absorb. Every state has issued mercury health advisories on eating fish, according to the EPA. Methylmercury poisoning can impair vision, walking, speech and hearing. Children suffer neurological damage with just a tenth of the exposure it takes to harm adults. A pregnant woman eating tainted fish can also can hurt her baby’s growing brain and nervous system. Women of child-rearing age are also advised to limit consumption of mercury-tainted fish because it takes eight to nine months for the body to purge the toxic. Colorado advisories to limit consumption are triggered when 0.5 parts per million of mercury or more is found in fish tissue. “The more we learn, the more damaging mercury turns out to be to a child’s brain,” said Gina Solomon, a senior scientist with the Natural Resources Defense Council…

“It is a complicated process, and we are trying to break it down,” said Steven Gunderson, director of water quality for the Colorado Department of Public Health and Environment. Lake Pueblo, for example, is not far from a steel mill but has no fish advisories, Gunderson said. Brush Hollow Reservoir, 30 miles away in Penrose, has a mercury problem.

In 2004, the state health department and the Division of Wildlife drew up a list of the 120 most-fished bodies of water and began testing their fish. About 112 have now been tested, and 23 have fish with elevated mercury levels — from Totten Reservoir west of Durango to Horsetooth Reservoir near Fort Collins. The “hot” fish species have varied from lake to lake and include walleye, lake trout, northern pike, largemouth and smallmouth bass, yellow perch, saugeye and wiper. “These are all predators, top-of-the-food-chain fish, where the mercury gets concentrated,” said Alisa Mast, a hydrologist with the U.S. Geological Survey.

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