Our research in near surface geophysics focuses on using the geophysical method, nuclear magnetic resonance (NMR), to understand processes occurring in the top 100 m’s of Earth’s surface. NMR measurements directly detect hydrogen protons water and are sensitive to their physical with chemical environment. Using NMR it is possible to non-invasively image the subsurface and obtain information about water content and pore properties. These measurements can be made from the surface or with an instrument lowered into a borehole and are typically used to characterize ground water aquifers. Through laboratory and field experiments, as well as computer modeling, we are developing new methods for interpreting NMR data to understand the link between NMR measurements and subsurface properties and processes.

 

One focus area of our research is to improve the way in which ground water monitor remediation is monitored and managed by measuring geochemical changes in the near surface using NMR.


The NMR response of hydrogen is greatly dependent on the geometry and magnetic properties of the geological materials in which they are contained. Since the magnetic properties of geological materials can be altered with changing chemical form of iron, NMR can be used to monitor chemical changes of iron in the subsurface. Iron, which is very abundant in the earth’s crust, is a highly reactive transition metal and can have a significant influence on the sequestration, mobilization, and detoxification of a wide range of common organic and inorganic contaminants. Remediation techniques used to clean up contaminated sites, such as biostimulation, bioaugmentation, or the construction of reactive barriers, often exploit the high reactivity of iron to control and sequester contaminants. In our research we have designed laboratory studies to assess the use of proton NMR as a geophysical technique to monitor changes in iron redox chemistry in soils. The ability to make such measurements in the subsurface of the earth will have a tremendous impact on the way which we design and manage the remediation of contaminated sites

Petrophysics

Field Research

Biogeophysics

A second focus area of our research is to improve the interpretation of NMR field data for hydrogeophysical applications.

Under construction

A simple diagram of an NMR experiment. When placed in a static magnetic field protons, with spin angular momentum, will align with the static field. A secondary field, oscillating at a frequency tuned to detect hydrogen, is then applied and used to move the protons out of alignment with the static field. When the secondary field is removed, the protons relax back to their initial state and emit a measurable signal.

Schematic of how NMR measurements might be used to monitor contaminant remediation. After a contaminant spill, NMR measurements would be taken prior to remediation to obtain a background signal. As the contaminant is remediated, NMR measurements would be collected over time. The difference between the NMR measurements before and after remediation could potentially help determine if the remediation efforts were successful and guide future remediation attempts.

Current Projects


The Use of Low-Field Nuclear Magnetic Resonance Measurements to

Monitor Microbial Growth. (More information here)


Integrated Geophysical Measurements for Bioremediation Monitoring: Combining SIP, NMR, and MS Methods. (More information here).


Low Cost In-Situ NMR Technologies for Monitoring Biological and Geochemical Processes in the Subsurface. (More information here)