Non-Intrusive Mercury Detection and Measurement

Contamination from mercury and other heavy metals in the environment can present a health risk to both humans and wildlife. Sources of these contaminants can be difficult to locate, especially if lost beneath the surface of old building materials and legacy equipment. This work will develop a portable imaging spectrometer for non-intrusive detection and localization of mercury hotspots. Depending on the material type, a penetrating neutron or photon source of radiation will be used to stimulate nuclear and atomic transitions within the contaminant, causing it to emit identifiable photon signatures that are detected by the sensor. With enough collected data, the direction of the contaminant can also be resolved. Phase I of this project will investigate the sensitivity of these pixelated, cadmium-zinc-telluride-based sensors to mercury contamination. A series of simulations and experiments will be conducted to quantify the time needed to detect a significant quantity of mercury. The results will determine whether the sensitivity of these instruments is useful for mercury remediation, and furthermore, if the device has commercial potential. Following a successful first project phase, the instruments will be optimized to enhance sensitivity. There are hundreds of superfund sites around the country with lead or mercury listed as primary contaminants, presenting a vast opportunity for cleanup guided by this sensor. Due to its penetrating signal and potential for sampling wider areas, this device is capable of reaching locations that are, so far, uncharacterized. This could lead to the discovery of hidden contaminants to initiate their removal, to the benefit of local wildlife and surrounding communities. Characterization of other contaminants and materials using this device will also be explored after the first phase. The two complementary methods for signal production and analysis that are paired with this sensor, called K-x-ray fluorescence and prompt gamma neutron activation analysis, have been used by environmental scientists, archaeologists, geochemists, and other researchers for decades. By providing signal directionality in a portable package, these sensors have the potential to change the way these scientists take their measurements.