In the future we might not need humans, or even robots, to go down into the Earth and hack out chunks of metal. With a little work, plants might be able to do the mining for us.
Which is good news, because mining for metals is tiring and dangerous for a human body. It requires moving huge amounts of soil and rock to slowly extract materials from the Earth. The process is, relatively speaking, inefficient, but the materials are often so precious that a large amount of waste is worth it.
One such material is nickel. We use it in coins, of course, but also in rechargeable batteries, electronics equipment, and stainless steel. It's precious to people, but poisonous to plants. Although a little in the soil is necessary for the plants to break down waste products, too much will kill the plant and pollute the soil. Nickel contamination can devastate an ecosystem.
The only thing that grows in these ecosystems is a special kind of plant known as a "hyperaccumulator." While other plants will find ways to rid themselves of toxic metals, hyperaccumulators will take those metals up quickly and without problems. A hyperaccumulator will stuff its excess nickel, or any other type of metal, in special organelles in its cells. It generally routes all the metal to the leaves, where bugs are more likely to eat it and be poisoned. (One theory for the recent collapse in bee populations holds that bees were harvesting pollen from flowers stuffed with nickel and aluminum.)
This gives humans a possible advantage. Mining nickel from polluted soil involves digging up tons of dirt, moving it to a special facility to extract the nickel, and then bringing it back. Because the metal is so valuable, that's how it's done. But it doesn't have to be!
Growing plants on the soil, then harvesting them and extracting the elements from their leaves, is comparably easy work. One plant, Alyssum Bertolonii, can yield about 350 pounds of nickel per acre, and there are other plants out there that can do the same work. One company, Viridian Resources LLC, got what they considered good results in nickel farming — or in making plants do nickel mining, depending on how you look at it — but there has been no development since the late 1990s.
Even if we don't use plants to mine, we can use them to clean. Certain plants naturally take up dangerous materials from the soil. Now, this can have a serious downside; from time to time warnings go out about herbal supplements being made from plants that take up cadmium or other toxic metals. On the other hand, this could also be an easy, natural way to clean a plot of land. The plants can even still be useful, as many plants route toxic metals to the leaves, rather than the fruit. People could potentially clean their land and sell the precious metals they harvest, all because of plant miners.
Top Image: German Federal Archives.