When Plants Get Metal: Part 2

©Maki Naro

A little while ago, I introduced the concepts of phytoremediation and phytomining, two of the ways that special hyperaccumulator plants can be used to clean the environment, and maybe make a little money. The above are just a few of these robust plants that not only thrive in toxic soil, but actually help make it more suitable for less hardy organisms. Organizations such as the USDA and the EPA are studying ways to not only use hyperaccumulator plants in soil clean-up, but how to help make it easier for plants to absorb the pollutants. For example, it was found that ammonium ion was effective in dissolving cesium-137 in order for it to be better taken in by plants.

So some of you asked, what happens to the plants now that they're full of toxic metals? Well, I hope you're ready for some more phyto-words. Most of the time, the plants are harvested, incinerated, and replanted. Much easier than trying to sift through the soil for the pollutants. But sometimes, in cases of phytodegradation (AKA phytotransformation) the pollutants are broken down the by plant and used as nutrients, and require no further action by people. In phytovolatilization, the pollutant is absorbed by the plant, and a modified version of the contaminant transpires into the air in low concentrations.

Hyperaccumulators can also be used to prevent pollutants from getting into water supplies through phytostabilization. This is where certain plant species are used to immobilize contaminants in the soil through absorption and accumulation in their roots. These plants can be used to create a vegetative cover over a contaminated area which prevents the spread of pollutants by wind erosion or leaching. Thanks, plants!

Next time, we'll take a look at the elite ranks of hyperaccumulators: Plants that absorb radioactive elements.