Phytomining: How Plants Could Do Our Digging For Us
By Lenny Pierce on March 15, 2014
What if mining for precious metals no longer meant descending deep down into the earth to go find them? What if acquiring minerals such as nickel, zinc, and cadmium was as simple as planting a few flowers and watching them grow? A concept called “phytomining” could make just such a phenomenon possible.
Certain metals occur in soil that plants will naturally absorb through their root systems. Plenty of metals are actually poisonous to plants, so most species will either die from absorbing them or expel them from their tissue before they can do any harm. Plants classified as “hyperaccumulators”, however, will collect and concentrate these toxic metals in their tissue. Seeing as these plants often store these metals in their tasty leaves, this may be a way of deterring herbivores from feeding on them.
Nickel is an example of one metal that can be sucked up and stored by a hyperaccumulator. For humans, the current the process of obtaining nickel from soil is a highly complicated one. It entails transporting all of the soil in question to a special facility to draw out the high-prized element and then trucking the soil all the way back once the extraction is over with. The inherent value of nickel (which we use in batteries, stainless steel, and, oh yeah, nickels) makes this laborious process somehow worth the effort.
A hyperaccumulator called Alyssum bertolonii could provide an easier option. A. bertolonii absorbs and packages nickel so well that massive fields of it could be planted in nickel-laden soil, and then be harvested for the metal. It is thought that extracting the metal from these leaves would be far easier than manually separating it from the soil itself. A single acre of A. bertolonii could yield 350 pounds of nickel. That’s a lot of Jeffersons.
Alyssum bertolonii (Brunello Pierini)
Even if phytomining doesn’t become the new standby for mineral acquisition, the process could still be used for the cleansing of ecosystems that have been contaminated with toxic metals. Planting hyperaccumulators could be a simpler way of drawing metals out of soil and making an area more suitable for plants that don’t necessarily want to suck up poison every day.