Iron is not a panacea for wild rice or for our children

Who is speaking for the children?

Carla  Arneson

There has recently been a series of pro-PolyMet articles written, concerning the impacts of iron, sulfate, mercury, and methyl mercury in the St. Louis River Watershed and the Lake Superior Basin; all of which contain misinformation, omissions, and faulty interpretation of cited scientific studies.

The articles, by Harlan Christensen, have continued to be represented as fact by the Mesabi Daily News, the Hometown Focus, and Conservationists with Common Sense, spreading inaccurate and misleading information without presenting the rest of the story or doing any additional fact checking.

Why are promoters of PolyMet’s proposed NorthMet Project so afraid of checking for accuracy? The purpose of PolyMet’s Environmental Impact Statement is to get the science right, not just get a mine permitted, or so mining proponents have declared. When he was a State Representative, Tom Rukavina stated: “The truth is I am simply seeking a solution grounded in scientific research that allows for the safest environmental mining in the world.”

The editor of Hometown Focus agreed to print a “counterpoint” to Christensen’s first article, “Iron Range sulfide mining can be done without harming wild rice or raising mercury levels,” since the paper had “opened the door” by reprinting Christensen’s piece. So I sent the editor my article on iron-reducing bacteria and methyl mercury, as well as an addendum detailing the results of the Berkeley iron amendment research that proved it – simply put – did not work. Hometown Focus did not print any of the information as a counterpoint, with no explanation as to why the editor reneged.

The following is a merging of two articles (with a few additions) from MinnPost and the Twin Cities Daily Planet, both articles written in response to Christensen’s. Written in response to the misinformation that sulfide-mining supporters in northeastern Minnesota have apparently accepted without question. Upton Sinclair once said, “It is difficult to get a man to understand something, when his salary depends on his not understanding it.”

All of the people living in the Arrowhead of Minnesota deserve the right to make up their minds about its future, their future, and the right to have equal access to accurate reporting of scientific information in order to make those decisions.

In spite of claims to the contrary, PolyMet’s proposed NorthMet project would add more mercury to the environment, increasing contamination of high-value Minnesota aquatic resources. Daniel Pauly, with a Harvard degree in chemistry, pointed out in his NorthMet Supplemental Draft Environmental Impact Statement (SDEIS) Comments, a fatal flaw: “the preparer’s of the SDEIS failed to appreciate that some of their data was in the units “ng/L,” and some of it was in the units “ug/L” (a ug/L is 1,000 times greater than a ng/L). This failure resulted in large errors in a key SDEIS summary of mercury contamination, which incorrectly states that the majority of water seepage sites were below the Great Lakes initiative mercury level, when in fact most of these sites were actually above the Great Lakes Initiative level.”    

Our high-value water resources already have severe “legacy contamination” problems. Taconite mining pellet production, foremost, and coal-fired power plants are the main sources of mercury releases in the Lake Superior Basin, adding to the mercury mix from legacy deposits accumulated in soils and river sediments from paper-mill discharges and atmospheric deposition. Almost four decades ago Minnesota’s Regional Copper-Nickel Study prophetically warned, concerning sulfide mining: “production near existing iron facilities might exceed established environmental guidelines” (Legislative Law Reference Library).

A year ago the Minnesota Pollution Control Agency (PCA) pulled out of a million-dollar study, a Mercury Total Maximum Daily Load (TMDL) of the St. Louis River — a study that would have identified and set limits on the sources of mercury released to its waters.

The reason given for the pullout: “Officials from the Minnesota Pollution Control Agency (PCA) said they are committed to reducing mercury pollution in the river and in the 10 percent of the state’s waters that have unusually high levels. But, they said, the agency’s lead scientists believe the state first needs more research on how mercury behaves in nature and why mercury levels in fish from the St. Louis River are significantly higher than in those elsewhere.” (StarTribune)

Iron and iron-reducing bacteria
The “why” could be iron and iron-reducing bacteria. Mercury methylation by iron-reducing bacteria in the sediments of the St. Louis River – in addition to methylation by sulfate-reducing bacteria – may well be responsible for the “significantly higher” levels of methyl mercury in fish from its waters; double doses of methyl mercury.

And that certainly ought to make agency scientists hesitant to throw more bacterial-stimulating sulfates into waters whose sediments have high iron content, the site-specific argument being used to rationalize changing Minnesota’s current sulfate standard, set to protect wild rice.

Minnesota has a critical problem with damage to wild rice, despite the limited effect that iron has on toxic hydrogen sulfide (iron precipitates out as iron sulfide). What about the critical damage to our children from the neurotoxin methyl mercury? What about the 10 percent of newborns tested in the Lake Superior Basin of Minnesota found to have “unsafe” levels of mercury in their blood, likely because their mothers ate mercury-laden fish from area waters? Where is the standard to protect our children?

Scientists at the University of California, Davis, discovered that iron-reducing bacteria likely play a significant role in methylation of mercury, comparable to that played by sulfate-reducing bacteria.

The abstract of the 2006 UC Davis study, “Mercury Methylation from Unexpected Sources: Molybdate-Inhibited Freshwater Sediments and an Iron-Reducing Bacterium,” states: “Methylmercury has been thought to be produced predominantly by sulfate-reducing bacteria in anoxic sediments. Here we show that in circumneutral pH sediments (Clear Lake, CA) application of a specific inhibitor of sulfate-reducing bacteria at appropriate concentrations typically inhibited less than one-half of all anaerobic methylation of added divalent mercury. This suggests that one or more additional groups of microbes are active methylators in these sediments impacted by a nearby abandoned mercury mine. From Clear Lake sediments, we isolated the iron-reducing bacterium Geobacter sp. strain CLFeRB, which can methylate mercury at a rate comparable to Desulfobulbus propionicus strain 1pr3, a sulfate-reducing bacterium known to be an active methylator. This is the first time that an iron-reducing bacterium has been shown to methylate mercury at environmentally significant rates. We suggest that mercury methylation by iron-reducing bacteria represents a previously unidentified and potentially significant source of this environmental toxin in iron-rich freshwater sediments.”

Mercury research needed for both sulfate and iron reducing bacteria
Given the politics polluting the science in Minnesota, new research is vital before any standards are changed or new mining permits issued. Minnesota needs to do a Mercury TMDL of the St. Louis River Watershed that includes not only accurate mass loadings of mercury from present-day and legacy sources of mercury, but also loadings of reactants controlling toxic methyl mercury production and bioaccumulation in fish, including sulfate and iron.

In 2010 and 2011, UC Davis participated in the PCA’s “Sulfate Water Quality Standard Study Protocol Development.” In 2011, The Minnesota Chamber of Commerce (Chamber) insisted methyl mercury could never be discussed during the Wild Rice Study. In 2012, the “Wild Rice Sulfate Standard Study” began its research projects. Even as the Minnesota Department of Natural Resources, Land and Minerals Division, research report file, “Sulfur and carbon controls on methyl mercury in St. Louis River Estuary sediment,” 2012, referenced not only the UC Davis study, but also, “Mercury Methylation by Dissimilatory Iron-Reducing Bacteria,” and, “Methylmercury production in a Chesapeake Bay Salt Marsh;” all three studies highlighted mercury methylation by iron-reducing bacteria. In 2013, the PCA suddenly, without warning, pulled out of the St. Louis River Mercury TMDL. In 2014, Minnesotans have yet to hear any serious public discussion or concerns raised by our agencies in regard to iron-reducing bacteria methylating mercury in our waters. Why not?

Who is speaking for the children?
Evidently there was an attempt during Protocol Development to bring up the issue of methyl mercury, but the Chamber squelched it. In 2011, Mike Robertson, attorney and consultant representing the Chamber, sent a letter to the PCA. (Robertson spent nine years with the PCA as its assistant and deputy Commissioner, another example of the “revolving door” in Minnesota between our agencies and industry).

In his letter Robertson stated, regarding the Wild Rice Research Protocol, ‘There should be no methyl mercury research conducted as part of the research on wild rice. There is no evidence that mercury or methyl mercury impacts wild rice. The draft protocol itself states that the Priority C hypotheses (methylation of mercury) “ not address the wild rice issue.”’ No methyl mercury research; even though there is plenty of evidence that mercury or methyl mercury impacts our children. Even though sulfate-reducing bacteria play a roll, not only in damage to wild rice, but also in the production of methyl mercury and damage to our children.

Iron-reducing bacteria also play a roll in mercury methylation, likely a significant one. The PCA decided, without any objections from the Chamber, to research iron in regard to wild rice. That decision surely clears the way to initiating a complete iron study, including iron-reducing bacteria and mercury methylation with all its complexities. To research the impact of iron on wild rice and not research iron’s impact on our children would be science without integrity.

Set the politics aside and let science do its job. Protect Minnesota’s children from toxic mercury poisoning. Are they not as important as wild rice?

Diversionary tactics
“Fear-mongering” is the latest buzzword being used by the sulfide mining industry and its supporters, used to divert attention away from the toxic metal poisoning of our children, primarily the result of a taconite industry that does not meet standards. If the grossly underestimated calculations for water flowage, water seepage, and mercury levels discovered in PolyMet’s SDEIS are any indication, the sulfide mining industry is planning to do the same; while PolyMet supporters are busy spreading misinformation.

Having failed to mention emerging and compelling research that iron-reducing bacteria is capable of methylating mercury at rates comparable to sulfate reducing bacteria, PolyMet shareholder Harlan Christensen claimed – wildly exaggerating – that there is “widely accepted scientific evidence that iron reduces mercury methylation.”

Christensen should have done more reading. The research he referred to, from an early, single, 2003 University of California, Berkeley study, has been ongoing and was revised in 2010: “Impact of iron amendment on net methyl mercury export from tidal wetland microcosms” (included referenced supporting material). The Berkeley research is still unfinished and flawed. It has not been tested in the field. Christensen has misrepresented the research, and used it inappropriately. It must be studied in its totality and in detail, recognizing that there is a distinct difference between saltwater and freshwater environments.

Iron amendment did not work as planned
The Berkeley research is not comparable or relevant to northeastern Minnesota. Its focus was on ocean tidal salt marshes and pools, about as far from the physical, chemical, and biological interactions of Minnesota’s freshwater aquatic ecosystems as it is possible to get.

Christensen stated: “Iron makes the difference, and we are talking about the Iron Range, right?” He was implying that there would be no problem with mercury methylation because there is iron on the Iron Range. Not only is it illogical because we already have a problem, it is also incorrect because the California researchers used ferrous chloride to treat their marine microcosms, a soluble, reduced form of iron. This treatment contrasts drastically with “Iron Range iron” which is not soluble as oxidized mineral forms; iron oxides such as magnetite and hematite.

As for mercury and sulfur minerals in vegetated microcosms the researchers stated: “The formation of these minerals [FeS and FeS2] could also be important to Hg bioavailability since they can be important scavengers of Hg (II), and mercury can coprecipitate with authigenic pyrite in marine sediments. In both cases, it is possible that mercury could be rendered less bioavailable. If this occurred following an iron amendment, it could provide a long-term means of reducing MeHg production, provided that the minerals are prevented from reoxidizing and releasing the associated mercury. However, it appears that iron-sulfur minerals did not affect the microcosms in this way, since the inorganic mercury concentrations were similar for all groups. It is possible that the high concentrations of porewater DOC [dissolved organic carbon] inhibited sorption to the minerals by forming complexes with Hg.”

Apparently unrecognized by researchers at Berkeley, their iron treatment acted directly on the mercury to change its form to elemental mercury, which then left the microcosm as a gaseous vapor. In the real world, this elemental mercury would cycle back through dry or wet deposition. See S6 or S8 In the study’s supporting material, which shows the total mercury being much less in the iron(II) additions than in the controls. (When contacted later, a Berkeley researcher responded, “We are aware of this reaction but did not study it in our wetland system.”)

Yet the lowest iron added to the system [devegetated microcosm] is higher in methyl mercury than the methyl mercury in the controls, making the conditions ‘worse’ and stimulating the formation of methyl mercury. As was stated, “This phenomenon warrants further attention if an iron amendment is used at the field scale because it would be problematic if elevated MeHg production occurs in areas that receive lower-than planned iron doses.”

As the Berkeley research cautioned in 2010: “Research at the field scale is needed to determine the efficacy of an iron amendment under field conditions, and if an amendment is effective for longer than 12 weeks or if repetitive dosing would be needed. Additionally, unintended consequences of adding iron to the ecosystem, including toxicity to wetland vegetation, must be taken into account to ensure that changes that alter habitat quality do not occur.”

A dangerous and foolish game
In Minnesota, to say that waters with high iron content can handle more sulfates or that iron can control methyl mercury is a dangerous and foolish game to play; particularly when the stakes are the health and intellect of our children. The Berkeley study does nothing to change the odds. The Berkeley study does nothing to change the present high levels of toxic mercury exposure in our children. Responsible mining officials must act to reduce toxic metal and mineral exposures in every way possible. That includes discarding the “not economically feasible” excuse, and putting an end to the accepted stratagem of passing the costs – the health consequences – to their workers and to our children.

I would suggest everyone read, “Some Ecosystems will Respond to Reductions in Mercury Emissions,” noting: “Forest canopies were found to be very active interfaces that accumulate atmospheric mercury. Year-round studies showed that with the onset of the annual autumn leaf fall, a substantial influx of mercury (heretofore greatly underestimated as a terrestrial mercury source) is introduced to the land surface, soils, and the watershed in general. Mercury researchers across the globe are now reevaluating whether deposition monitoring in the form of precipitation in open settings is a reliable estimate of mercury loadings to watersheds.” This important issue was not thoroughly evaluated by PolyMet or by Minnesota’s cooperating agencies in the NorthMet SDEIS.


“Methylmercury is produced from inorganic mercury by methylation, a microbial process that is controlled by certain bacteria and enhanced by chemical and environmental variables, such as the presence of organic matter and oxygen.” (USGS) In freshwater systems such as ours, sulfate and iron reducing bacteria (and others) function in anoxic sediments, meaning without oxygen.