Trees Release/Concrete Eats, Part 2

Last week I noted there were two studies that caught my eye, the first being the one in Science suggesting we plant trees and more trees as quickly as we can.  That’s obviously where the first part of these posts’ title comes from, Trees Release Oxygen.  The second part of the title was a reference to Biosphere II’s problems with Concrete Eating Oxygen.  I stumbled on a story about that project that led me to some really interesting reading on the experiment and its problems and successes.

If you don’t recall the news from back then, in the early 90’s, a group attempted to replicate “Biosphere 1,” which of course is our own Earth.  Eight people went to live for two years in a massive sealed complex hosting a wide variety of ecosystems outside of Tucson.  Unsurprisingly, they had plenty of problems, but most significantly, where did all their oxygen go?

This was a sealed system with a TON of trees and other plants—you would have thought that enough oxygen would be the least of their problems.  But they faced a steady decrease in the percentage of O2 in the air and after about a year in a half, it reached 14% (rather than the original and normal 21%) and outside oxygen actually had to be pumped into the environment. 

It wasn’t a leak though, not that leak would have been oxygen specific of course.  But to confirm, this was a really well-sealed complex–Biosphere 2 leaked just 10 percent of its oxygen A YEAR. In contrast, the space shuttle leaks 2 percent A DAY.

There were two primary culprits:  curing concrete eating oxygen (in the form of CO2) and insufficient carbon sinks because the plant material was rotting, not growing.  (I’d suggest that implies the solution on a grander scale is, you guessed it, more trees!)   

How did this happen?  A TED talk with Biosphere 2 resident Jane Poynter explains:

(we need to) see if we could, in fact, find where those seven tons of oxygen had gone. And we did indeed find it. And we found it in the concrete. Essentially it had done something very simple. We had put too much carbon in the soil in the form of compost. It broke down; it took oxygen out of the air; it put CO2 into the air, and it went into the concrete. Pretty straightforward really.

Simplifying the concept, growing plants “eat” CO2, but keep the Carbon and release much of the O2.  On the other hand, concrete’s greedy, it keeps both the carbon and the oxygen.  (Rotting plants will release the carbon they held on to, which is why wood floors are considered such great carbon sinks—keep that wood from rotting and you keep that carbon inert and out of the atmosphere.)

Some called Biosphere 2 a failure and for sure, it could have done so much more.  But on the other hand, scientists often find failures useful.  For example here are two interesting takeaways:

But we learned a lot. Biosphere 2 taught us that concrete takes years to fully cure (which is what was pulling the oxygen out  – but something engineers did not really understand since they hadn’t built concrete in enclosed environments at any large scale before).


The oxygen deficit was seasonal and worst when the biomes were shut down for winter. The crew was able to manipulate the arid (desert and savannah biomes) by adding water at the right time to green up out of season with the rainforest (thereby releasing some oxygen) to help ameliorate the oxygen problems. So these two articles reinforce my belief that we really really really need to plant more trees!  Here are a few hundred thousand ready to go which will grow up helping the earth and eventually become fine floors in someone’s home:

Want to learn more about Biosphere 2?  Some of the more interesting and easy reads I found (and didn’t cite above, see those links too for more tidbits.)

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Elizabeth Baldwin is Environmental Compliance Officer for Metropolitan Hardwood Floors. In her 25 plus year career in the wood industry has visited over 70 countries and hundreds of facilities of all sizes and types. She describes herself as a “jack of all wood trades.” Familiar with jungles of all sorts–having camped out along the Amazon and walked the halls of Congress–she blogs for the NWFA on both environmental and regulatory issues for educational and informational purposes only. Her blog is not intended and should not be construed as legal advice. Persons seeking legal advice on compliance with CARB, TSCA, the U.S. Lacey Act or any other law, regulation, or compliance requirement/claim should consult with the regulatory agency directly and/or a qualified legal professional.

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