In-situ Subsurface Soil Analyzer

Through its various interactions with the rest of the earth, the terrestrial ecosystem plays a vital role in the biosphere. For example, terrestrial ecosystems often serve as a "sink" for anthropogenic carbon, affecting the greenhouse gas concentrations and the climate. The study of the subsurface elements of terrestrial ecosystems is particularly important because it improves our ability to model terrestrial ecosystems and their feedback to the atmosphere with high fidelity and resolution. To better understand the subsurface environments of terrestrial ecosystems, testing of advanced models describing complex, coupled interactions in subsurface systems is necessary. Reactive transport models offer a powerful theoretical platform for understanding hydro-biogeochemical processes present in complex subsurface systems of the terrestrial ecosystem. With rapidly increasing computational capacity available to these models, the biggest hurdle to enhancing the predictive power is the accuracy of experimental data available to represent the model system. Currently available experimental tools either lack significantly in the ability to deliver high-resolution, high-fidelity data in field measurement settings or do not provide sufficient portability, requiring significant efforts and expertise for sample collection, preparation, and preservation. To address this need for subsurface soil characterization, development of a field-deployable, in situ soil analysis system is proposed. The system is based on remote soil analysis technologies that allow detection and characterization of redox-sensitive elements and groundwater for depths up to 2 m and resolution of ~10 cm. The proposed design also allows quasi-continuous monitoring of a subsurface soil sample in its natural environment. A breadboard prototype for in situ soil probing technology will be constructed, its performance will be evaluated, and a feasibility demonstration of the technology will be performed. The technology will allow in situ, real-time monitoring of reduction/oxidation reactions involving redox-sensitive elements such as iron and manganese. It can also be used to obtain a depth-resolved moisture profile. Based on the results in Phase I, the Phase II prototype concept with its projected performance metrics will be proposed. Commercial Applications and Other Benefits: In addition to terrestrial ecosystem studies, in situ subsurface probing could be extremely useful in agriculture and environmental monitoring. A portable instrument providing quasi-real time analysis of subsurface composition with a high depth resolution will allow quick and reliable analysis of soil and have a broad impact in these industries.