Real-time Dissolved Oxygen Monitoring for Understanding Biogeochemical Processes in the Hanford Reach Columbia River Hyporheic Zone

One of the overarching goals of the Department of Energy’s Biological and Environmental Research (DOE-BER) program is the quantification of biogeochemical processes in complex subsurface environments such as at the Hanford Reach zone. Pacific Northwest National Lab (PNNL) has developed sensor networks along the Hanford Reach in past and current projects, and anticipates a need for expanded sensor networks in the future in order to meet the research goals of its Science Focus Area. Dissolved oxygen (DO) monitoring is a key component of these research goals, but currently available commercial DO sensors are not suited for extended use within these sensor networks. The sensing network at the Hanford Reach site comprises a network of aquifer sampling tubes emplaced in the hyporheic zone of the Columbia River. Phase I of this project focuses on applying a novel and robust oxygen sensing technology as the basis for the automated measurement of dis- solved oxygen (DO) in groundwater drawn from multiple locations via this sampling tube network. In Phase II the system will be expanded to provide a robust and cost-effective solution to the challenges of spatially and temporally resolved environmental DO monitoring in a complex setting. Commercial Applications and Other Benefits The successful development and validation of a flow-cell based DO measurement capability will al- low the OptiO2 oxygen probes to enter new market sectors including industrial process controls and benchtop instruments. The validation of the aquifer sensing tube approach to environmental DO monitoring will provide a cost-effective solution to the challenges of characterizing groundwater at complex sites such as the Hanford Reach zone.