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BACK ROADS BILL: Natural geobatteries explained

This week Bill leads us to some circles and rings on the northern Ontario landscape which underlines the importance of science

This story has an aerial perspective.

When you locate a mystery on the back roads you look forward to solving it even though you can’t see it on the ground!

They are not crop circles made by the aliens. In other places in the world, they are called “fairy” circles. Perfectly round, thousands of them, dotting the landscape of the boreal forest. This natural curiosity would lead me to the expression: “biting off more than you can chew.”

But first, you will have to have a look at this week’s story photos and the map link Zoom in slowly until you see the bunch of circles NE of Cochrane and the “X” transect on the other map pin NW of Hearst near Fushimi Provincial Park.

And then we have to embrace our chemistry and physics backgrounds no matter how scant they may be.

Google Earth becomes important. These light-coloured rings are clearly visible from the air but not on the ground, there are thousands of them identified in northern Ontario. They range in diameter from 30 metres to two kilometres, discovered more than a half-century ago through aerial interpretation. Apart from the theory of extra-terrestrial doings, others suggested the rings might be the result of meteor strikes. That got the prospectors interested in diamond-bearing kimberlites.

What about this phenomenon?


As always an expert has to be located and Stewart Hamilton was eventually found.

He is retired as a geochemist from the Ontario Geological Survey in Sudbury. His PhD from the University of Ottawa was on the subject of aqueous geochemistry—in particular, the electrochemical dispersion of elements around ore bodies and other buried features.

Perfect, he will know about these strange features seen only from above. A word of warning stay with the science.

Hamilton said the circles are caused by giant, naturally occurring electrochemical cells. These centres of negative charges are called reduced chimneys, ”vertical zones in overburden or groundwater that have lower redox or transfer of electrons.”

I felt overcome with regret, because of those missed high school classes.

“If you can think of these as natural electrical batteries with a negative charge in carbonate soil and surrounded by oxygen that carries a positive charge."

“Force goes out in a circle," Hamilton says. "For example, throw a stick in the water. At first, it makes a stick shape when it hits the water, then perfect circles go out from that.” Electricity is just the same.

“The current from the batteries — the negative charge — travels outward and where it meets the positive charge, acidic conditions are created that eat away at the carbonate soil, causing it to drop in a circular depression around the natural battery.

“We have done additional research and published a few papers on the subject. It appears that we were right in our speculation that bacteria are key to generation of the forest ring features.

"As we know then, forest rings are analogous to geo-batteries and have associated electrical fields, an oxidant (oxygen), and a reductant of some kind, which is usually buried organic matter or methane.

“But the observed electrical fields cannot be produced without electronic conductors (wires) of some kind, because they are required to create the charge separation that causes the electrical field. We had speculated that the 2006-discovered electrical bacteria Geobacter sulfurreducens was responsible for creating the electrical fields.”


The term geobacter was new, it is a genus of bacteria. These species are anaerobic respiration bacterial species which have capabilities that make them useful in bioremediation.

This is the use of microbes to clean up contaminated soil and groundwater, the boreal forest of northern Ontario is a repository of soils and aquatic sediment where geobacter thrive.

“Our research since has shown that there is a 50-fold increase in the abundance of Geobacter at the ring edge where the redox-gradient is strongest.

"Geobacter have pili, which are thread-like appendages that are capable of extra-cellular transfer of electrons. In other words, they act like nanowires. Our theory is that billions of bacteria all point their pili in the same direction, which is outward from the ring centre, because that is the direction which they can pass on electrons to oxygen outside the ring. Their tiny electrical fields merge into a very large one that is torus (doughnut)-shaped, with return current moving downward, then back into the ring from below.

“The Geobacter do not act alone but work in a consortium, which is a group of different types of organisms working together for mutual benefit. We don’t know the details of this consortium, but we think that it includes methanotrophs (methane-eating bacteria) and perhaps many other types of organisms.”

So that’s how the circles are formed!

They weren’t right about everything.

“We knew that the ground becomes acidified around the ring edge, which results in dissolution of carbonate in soils to the point where it forms a circular topographic depression. We thought the acid comes from inorganic oxidation of dissolved metals such as iron. However, it appears, based on carbon isotopes, that it again results from bacteria – in this case, due to carbon dioxide respiration and carbonic acid production by the hugely increased abundance of organisms at the ring edge.


Since these are mini 'geo batteries,' I wondered if we could we harness this energy. Stewart politely replied, “Not unless you devise a Matrix-like (the 1999 dystopian film starring Keanu Reeves) system for harnessing tiny amounts of bioenergy and nobody has done that yet.”

Microbiologists at the University of Massachusetts Amherst have discovered a new type of natural wire produced by bacteria that could greatly accelerate the goal of developing sustainable "green" conducting materials for the electronics industry.

Geobacter appear to be ubiquitously present in the earth and may be a key species that allows many other types of organisms to survive in environments they couldn’t otherwise tolerate (by sucking away or supplying electrons, allowing them to “breath” or “eat”). So yes, it is beneficial, and we are only just beginning to understand its importance. Its function was only first recognized in 2006.

He explained, “The rings are visible because the bacteria dissolved the carbonate, creating a (barely) visible circular swamp. The same phenomenon likely occurs in areas where there is no carbonate in the soil and would not be visible.

Regarding exploration, “Almost everything geologists are interested in is negatively charged, so this type of research may help locate buried mineral deposits or natural gas.”

Back to the map.

A company called Diatreme Explorations drilled that site in 1999 looking for diamonds and they added the “X” (Hearst pin).

Stewart said you will notice that there are drill roads across many of these rings, where people over the years have thought they might have been diatremes, which are volcanic features that host kimberlites (diamond-bearing rock).

“But they could be right – kimberlites produce some of the most reducing natural waters anywhere on earth. That is to say they are about as electrochemically negative as water can get and would very easily form geobatteries.”

Some final words from Stewart.

“There is plenty left to learn about the forest rings, but I am winding down my research career. I have retired from the Ontario Geological Survey and work in consulting now. I have copied some of my colleagues and coauthors, some of whom may continue researching these very interesting features. I may help out from time to time.”

And then I thought, why do we tend to care more about entertainment and sports figures rather than our scientists?

The alien explanation was understandable and easier to digest. There is more to ruminate on when comes to these geographic anomalies. There is much to learn on the back roads. Stay tuned.

Bill Steer

About the Author: Bill Steer

Back Roads Bill Steer is an avid outdoorsman and is founder of the Canadian Ecology Centre
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