Environmental engineer Amy Keith and her team developed a low-cost detector of contaminants in plants and surrounding groundwater. The non-destructive technology scans the surface of a leaf for spectral signatures. NASA currently seeks a development partner for the hyperspectral estimator.

Amy Keith, Environmental Engineer
NASA Tech Briefs: Why is it important to detect trichloroethylene (TCE) in plants?

Amy Keith: Trichloroethylene is the most common groundwater contaminant across the United States. To be able to detect it in a quick, nonintrusive manner would be much simpler and less expensive than the methods we have now to do it: put in wells, take a water sample, take a soil sample, send it to a laboratory, and wait for the results. Sometimes the turnaround can be a month, depending on how busy the labs are.

NTB: How does the device detect TCE?

Keith: With the new method, you would scan a leaf that you thought might potentially be over groundwater. It would be a quantitative indication. It wouldn’t tell you how much TCE; it would tell you if there was a high probability that the site had contaminated groundwater underneath it. Hyperspectral imaging measures the light that is reflected off objects, and that pattern of light is characteristic of that object and can be used later to go back and identify it. If that light pattern changes, it can be an indication that the characteristics of the object have changed. We know the wavelength patterns of a non-exposed leaf, and we know the wavelength patterns of an exposed leaf.

NTB: What does the detector look like?

Keith: It looks like a camera, and it has two big lights that shine down on the object being imaged. The photons bounce off the object, and they are collected in array wells in the hyperspectral imager. [The imager] measures how many photons go into the array, and that’s the strength of each wavelength. Then, we do statistical analysis and say, “Ok, statistically we see this kind of wavelength pattern for this exposure.” We also have signatures that are associated with water and nutrient stress.

NTB: How did this technology come about?

Keith: I was reading an article in the Marshall Star [a NASA publication], and I saw that there was a team coming onsite to image metal bending. The imaging technology could be flown over and tell the difference between normal corn and hybrid corn in the same field. Being an environmental engineer, I wondered if it could tell the difference between a contaminated plant and a clean plant. When the team came here to Marshall to do the imaging, I explained my idea to them, and they thought it would be a good application.

NTB: What are other applications for this device?

Keith: We would love to try it out with other contaminants. We have a project that we’re hoping to develop with the US Environmental Protection Agency (EPA) to use the technology to monitor mining sites. Their sites are huge and contaminated with metals. We could put [the camera] on a drone or aircraft and do flyovers of their mining sites. Because they are hundreds and hundreds of acres, it’s very difficult to monitor that large a site. The idea is to fly over on a periodic basis and see any changes in the vegetation.

We’d also like to look at chemical warfare munitions contamination. We’d like to see if we can use it in a nondestructive way to monitor ecosystems like wetlands, or to possibly to monitor food sources for long-range space travel.

To listen to this interview as a podcast, click here.

NASA Tech Briefs Magazine

This article first appeared in the October, 2015 issue of NASA Tech Briefs Magazine.

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