by Duane Craig
|(Image: Bo C. Christiansen/University of Copenhagen)|
There are two ways of handling soil-borne contamination: phytoremediation, and removal, disposal and replacement. The second option is extremely expensive, while the first one will not work on all types of contamination.
But what if you knew there was a possibility of contamination and you had a substance that would neutralize it before it became a problem? That could turn potential polluters into stewards.
Enter green rust. One of the precursors for this type of rust is a certain type of clay called anionic clay. Green rust lacks some electrons so it reacts with other pollutants, including radioactive pollutants. The substance has been reported to capture and encapsulate neptunium, a byproduct of nuclear reaction that is produced by nuclear power plants. This material takes millions of years to break down so for all that time it can potentially contaminate groundwater.
Green rust also has beneficial effects on other kinds of contaminants such as chromium VI. It will turn chromium VI into chromium III, its nontoxic cousin and a necessary trace element for humans.
The drawbacks to the material are that it doesn’t naturally occur in large quantities, and in some situations it becomes the contaminant itself by corroding the reinforcement bars in concrete. However, its near-future use seems to be as a factor designed into nuclear waste storage facilities.