Idle Speculation
Posted by Ray @ 1:16 pmA friend of mine sat on the bus wondering if the air she was breathing could be the same air the dinosaurs were breathing. Never one to leave it at that, I’ve decided to take a closer look and see if it’s really possible (idle thinking alert!).
By volume, air is:
78.1% Nitrogen
20.9% Oxygen
0.93% Argon
0.04% Carbon Dioxide
Some Neon
Some Helium
Some other gases…
Nitrogen is involved in the nitrogen cycle. Free N2 gets fixated by various means (lightning, bacteria, humans) and is then used by plants, which need it to make chlorophyll, which is used for photosynthesis. Nitrogen is also constantly being replenished by bacteria and fungi, which break down rotting biological matter. So while it’s possible that we’re breathing in the same nitrogen that dinosaurs breathed, it’s also highly probable that we’re eating them in our vegetables, too. Especially the really green ones.
Oxygen is involved in our respiration process, in burning stuff, etc. It’s a very promiscuous molecule, reacting with lots of stuff to form oxides. Most of it is locked in that form with the rocks in the Earth’s crust. Plants release oxygen as part of photosynthesis: some oxygen comes from the soil, some comes from carbon dioxide. And so on. So while it’s possible that we’re breathing in the same oxygen that dinosaurs breathed, it’s much more likely it’s locked in with rocks that were subsequently buried, or it’s locked in with limestone formed from all those shellfish, or it’s locked with some other oxide somewhere.
Similarly, Carbon dioxide gets put through several interesting reactive processes. It dissolves in the ocean, it gets broken down by plants, it gets absorbed into organisms for making shells, etc. Carbon dioxide (and monoxide) also comes from burning organic fuels (like petroleum), because the carbon in them reacts with oxygen. And so on. So again, it’s more likely that we’re not breathing in carbon dioxide that dinosaurs breathed.
That leaves us with the noble gases, the ones that hardly react with anything at all. The largest portion in the atmosphere belongs to Argon, which is also used to fill tungsten light bulbs because it’s just so un-reactive. The atmosphere also has trace amounts of helium and neon. According to Wikipedia, “no conventional compounds of helium or neon have yet been prepared”.
So there you have it. If dinosaurs breathed in argon, neon or helium, then there’s a high chance we’re breathing the very same atoms of argon, neon or helium ourselves, simply because they’ve not reacted with anything or gotten swept away. The ancient atmosphere had more oxygen than the current one, but I don’t know that the proportion of noble gases present has changed.
Corrections are welcome! But don’t take this seriously. It is, after all, just idle speculation.
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[…] In the last second, cesium-133 atoms around the world oscillated through 9,192,631,770 radiation cycles in atomic clocks measuring International Atomic Time (TAI)*. While you read the previous sentence, 400,000 billion neutrinos from the sun passed through you*. By the time you finish reading this paragraph, you will have inhaled nitrogen atoms that were also inhaled by dinosaurs 65 to 230 million years ago*. […]
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