“…These new approaches also must encapsulate sustainable metrics such as real-time monitoring, low-cost/low-energy consumption, and low environmental impact ͑Ellis and Hadley, 2009͒. Traditionally, geophysical methods have been employed to image physical properties of the subsurface, and only recently have geophysical responses been linked indirectly to microbial activity ͑Atekwana et Atekwana and Slater, 2009͒. The need to more precisely correlate the effects of mineral surfaces, microbes, and the products of microbial activity with common geophysical measurements has led to an increasing number of laboratory studies ͑Ntarlagiannis et al, 2005a; Williams et al, 2005;Davis et al, 2006;Slater et al, 2007;Personna et al, 2008;Abdel Aal et al, 2009͒ and initial field studies designed to validate upscaling of the approach ͑Williams et al, 2009͒.…”