In an ancient chain reaction, as land-based plants evolved to become larger, it's believed their roots sought to extract more mineral nutrients from the rocks, eroding them and exposing them to the air. That in turn led to a massive reduction in CO₂ in the atmosphere. Could the same effect be repeated?
The concept is to take the volcanic rock basalt, grind it up into a powder and then scatter it on fields. Trials on a research farm in Illinois have found that the basalt acts as a fertiliser, boosting crop yields, which might help persuade farmers to use it instead of high-carbon artificial fertiliser.
And early results from smaller experiments in Prof Beerling's lab in Sheffield show a more profound benefit: that the presence of the rock in the soil also boosts the amount of carbon dioxide that's taken up, maybe by as much as four times.
Where would all this rock come from? If it all had to be freshly dug up, the environmental cost might doom the idea from the start. But the industrial age has cleared billions of tonnes of the right kind of rock from open-cast mines and has also generated massive amounts of "slag" - waste from iron and steel production - which could also be used.
"Globally we produce half a billion tonnes of slag around the world," he said, "and that could capture something on the order of a quarter of a billion tonnes of CO₂. So it's not going to do everything but it might be relevant for us."
https://www.bbc.com/news/science-environment-46345280
Slag is frequently full of other, more toxic things, though. I can recall at least three environmental disasters in the US over the past few decades when holding ponds full of heavy metals burst or leaked, or piles of tailings did unfortunate things when weathered or dumped in lakes. I'm sure there were dozens more.
ReplyDeleteWe could engineer (re-engineer) some coral to resist acidified oceans. Might work except that carbonic acid dissolves CaCO3. So they'd have to fix CaCO3 faster than they get dissolved.
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