The cold war era has left a legacy of 6 billion cubic meters of contaminated subsurface water and groundwater. While a significant effort has been spent in subsurface remediation with approaches including, pump and treat, nanoparticles, bioremediation, etc., the results have been less than desirable. One of the major reasons for that is a lack of complete understanding of the physical, chemical, and biological processes affecting contaminant transport and transformation in the subsurface environment. Such an understanding is largely inhibited by not only the complexity of geo-structure, chemical environment (pH, ionic strength), and the diversity of the microorganisms present in the subsurface, but also due to the lack of adequate technology allowing an investigation of the effects of these multitude of factors at the depths of interest that quite commonly range from 0 to 100m.
A new noninvasive subsurface imaging technology, the Alternating Target Antenna Coupling (ATAC) method, has recently been developed at the University of Arizona. Along with ATAC measurements, nano zero-valent iron (nZVI) remediation (with low-frequency magnetic signatures) offers a potentially transformative approach in elucidating the effects of various physical, chemical, and biological processes on subsurface contaminant mobility and transformation. Perhaps most importantly, this monitoring of the coupled physical, chemical, and biological processes is noninvasive. This new imaging application may provide an important enabling scientific tool for environmental remediation.