The Great Oxygenation Event

Written by Dr Klaus L.E. Kaiser

There is an epoch in the Earth history termed the “Great Oxygenation Event” (GOE). I described it in my recent post on the rise of molecular oxygen in earth’s atmosphere. goe1

The “Great Alkalinity Event” is really just another “side-effect” of the GOE, namely causing most water on this planet to become alkaline, the opposite of acidic.

As you might have guessed already, there is more chemistry involved – my favored subject. Trust me; I’ll try to keep it simple, short and to the point. If still in doubt, just confer with my dearest about that!

Oxygenation = Reduction

The increase of molecular oxygen in the atmosphere by the GOE was by way of loss of that oxygen from the then highly ubiquitous carbon dioxide (CO2). In chemical parlance, the (fully oxidized) carbon dioxide got ”reduced” to material with less than two oxygen (“O”) atoms per carbon (“C”).  The notation “CO2” simply is the chemists’ short form for carbon-di(meaning two)-oxygen atoms for a compound (also termed molecule) consisting of one carbon and two oxygen atoms.

Just like in physics, where energy or mass cannot be created but only converted from one form to another, the same law of “energy/mass conservation” also demands conservation of atoms. Therefore if one substance gains any atoms, another must lose the same number and kind. In contrast to “money,” that many of the world’s central banks can create with a “mouse click” and “ex nihilo,” both chemistry and physics command adherence to a balanced mass equation.

The Mass Balance

So, if the photosynthesis process were simply converting part of the CO2 to molecular oxygen (O2) what would be left behind? You might (rightfully) think “C,” the chemical notation for the carbon atom. Well, nature’s chemistry is a bit more complex. Specifically, it also involves the water molecule that is made up of two hydrogen (“H”) atoms and one oxygen atom; hence the chemical notation for water is “H2O.”
The chemical notation for the mass balance equation then becomes:

CO2 (carbon dioxide) + H2O (water)  =  O2 (molecular oxygen)  + CH2O (plant matter)

As you can see, apart from molecular oxygen (O2), that’s the stuff we breathe in to keep us going, the photosynthesis process produces plant matter (“CH2O”).  That’s the real driver of the process. If the plants were not getting something beneficial or useful out of it, why would they bother with photosynthesis at all? They do it to create substance for growth and propagation, the driving force for all life on earth.

That “plant matter” (CH2O) is no longer an acid like the CO2 when it first dissolves in water. That formerly acidic CO2 has now been reduced to a neutral material that is neither acidic nor alkaline. If you don`t believe me, just chew on a piece of wood, it`s not acidic – in contrast to the carbon dioxide it`s made from.

Now, just add another small wrinkle to that equation, namely the concurrent reduction (de-oxygenation) of nitrogen (“N”)-oxygen compounds in the water. Let’s call that the “alkalinisation” process, or AP for short.

The Alkalinisation Process (AP)

The incorporation of nitrogen atoms into the plant matter (CH2O) described above then produces something like CH2O-N, or in common (semi-alphabetical) chemical notation “CH2NO.”

In reality, there is not one nitrogen atom per each carbon atom but only about one N atom for 10 plant matter molecules but that’s not critical here. The important fact is that this nitrogen atom imparts an alkaline property onto the product. Some of these nitrogen-containing products are not only alkaline but also smelly, like in the smell of fish. I`m quite certain that you are familiar with that as most likely you`ve handled fish in your life, perhaps whole fish or fillets. Some fish are more smelly than others, some have shiny scales, others don`t. However, they have one thing in common and that is that they all smell like fish. So, what causes that fishy smell?

The Smell of Fish

The smell of fish is caused by (yeah, more chemical stuff) amines. Amines are materials where the CH2NO has been reduced further, in other words lost yet more oxygen. They are, in chemical notation, now just “CH2N.” Such type of compounds are smelly and when dissolved in water cause its “pH” (a measure of its acidic or alkaline property) to rise. You can easily test that with some “litmus” paper or another pH indicator system.

By definition, any water with a pH value above 7.0 is alkaline, the opposite of acidic (pH value below 7.0). Put that fact together with another fact and you’ll begin to get the whole picture. That other fact is that the pH value of most water is well above 7.0.

The important part of this is to recognize that all that AP relies on the presence of CO2.

The pH of Water

Except for some lakes that are directly affected by “acid rain” or for other specific local reasons, freshwater and ocean water is alkaline. By and large, the pH value in these water bodies is well into the alkaline range, with the ocean pH in the order of 8.0 to 8.2. As the pH scale is an inverse logarithmic scale, each unit (for example going from 7.0 to 8.0) represents a one-order-of-magnitude change in hydrogen-ion (“H+”) concentration. A change from pH 7.0 to pH 9.0, therefore, means a 100-fold reduction of the acidity or a 100-fold increase of the “alkalinity” of the water.

By now, you may realize that the “acidic” CO2 and photosynthesis does not cause a decline of the pH in natural water but an increase instead. In fact, that has been documented by the annual pH spikes observed in ocean water like at the ALOHA Station offshore Hawaii and in freshwater at the Experimental Lakes Area in Canada. When the photosynthesis activity is strong, i.e. in spring and summer, the pH of the water rises. You can demonstrate that yourself with a simple experiment that I have previously described. Give it a try, it’s easy to do (next to no work required), the ingredients cost next to nothing and it will amaze you.

However, you can even get by doing absolutely nothing other than checking the pH of a nearby lake or pond a few times. Right now is a perfect time to start with that “experiment” in the mid-latitudes.  Over the next few weeks, nature will re-awaken from its winter slumber. The trees will be budding and the algae in the water will start multiplying and consuming the CO2 accumulated over the winter. The water will get turbid by the increased algal abundance and its pH will increase.

All that because of the “evil” carbon dioxide; welcome to nature’s alkalinisation event!


Dr. Klaus L.E. Kaiser is author of CONVENIENT MYTHS, the green revolution – perceptions, politics, and facts

Dr. Kaiser can be reached

Comments (1)

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    Elaine Supkis


    Yes, when single celled creatures we call ‘algae’ evolved suddenly, when these critters were able to suck in CO2 and capture the C while spitting out the O2, the atmosphere changed radically and the chemistry of our planet was altered beyond all belief!

    Which is very funny since ‘climate change’ has been continuous on this little planet. Trying to literally freeze climate in place is ridiculous. Might as well tell the oceans to not rise and fall.

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