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 at the Hanford Reach of the Columbia River in Washington and East River flood plain in Colorado. The models informed by this data are useful for predicting both short- and long-term changes to economically important ecosystems. Distributed sensors for dissolved oxygen (DO) concentration measurement are needed within river corridors. These settings are of particular interest because of the important role DO plays in catalyzing a diversity of environmentally important biogeochemical reactions. Additional the need for soil- or sediment-based DO sensors is every bit as great as for aqueous environments. Currently no viable and/or reliable DO probe exists on the market for making such measurements, which are critically important for a wide variety of researchers and scientists. How this Problem or Situation is Being Addressed We are deploying dissolved oxygen sensors for autonomous (hands-off) monitoring of across an entire ecosystem over the period of many months. What was done in Phase I In Phase I we established the first version of a remote sensing station in the East River, Colorado watershed in collaboration with our LBNL colleagues. The Aquifer Sampling Tube Network was instrumented at the Colorado River by our PNNL colleagues. We built and tested the flow cell for the Network manifold. The details of instrumentation deployment are in place for the spring deployment. What is planned for Phase II of project This proposal involves the Scientific Focus Areas (SFA) managed by the Lawrence Berkeley National Laboratory (LBNL) and the Pacific Northwest National Laboratory (PNNL). At the Berkeley Lab’s Watershed Function SFA the focus will be on quantifying seasonal variations in pore water DO within two critical components of the East River, Colorado, watershed: (a) streambed sediments undergoing hyporheic exchange with river water and (b) hillslope soils impacted by transient inputs of snowmelt. Investigations at the PNNL site will deploy sensors into the sediments in the variably saturated zone to capture the O2 dynamics during the transition times between saturated/unsaturated conditions. Commercial Applications and Other Benefits DO measurements provide critical information for many areas, including water-quality assessment and groundwater contamination modeling. Opti O2’s sensor will improve data gathering performance and reduce cost. These technological developments will also enable the deployment of ecosystem-scale DO sensing networks that will provide information critical to the improvement of predictive ecosystem models.