Scientists at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and Savannah River National Laboratory have developed a method for real-time monitoring of pollutants using commonly available sensors.
The study is titled “In Situ Monitoring of Groundwater Contamination Using the Kalman Filter”.
“Conventional methods of monitoring involve taking water samples every year or every quarter and analyzing them in the lab,” said Haruko M. Wainwright, a Berkeley Lab researcher who led the study. “If there are anomalies or an extreme event, you could miss the changes that might increase contaminant concentrations or potential health risk. Our methodology allows continuous monitoring in situ using proxy measurements, so we can track plume movement in real time.”
The new approach starts with sensors tracking water quality variables that have been determined to be reliable indicators of contaminant levels. The researchers tracked levels of tritium and uranium-238 in the groundwater at the Savannah River Site, a former nuclear weapons production site in South Carolina managed by the United States Department of Energy.
For this site, they measured the pH levels and specific conductance, and the variables were determined to be reliable indicators for tritium and uranium-238 concentrations. The data from the multiple sensors were then fed into a Kalman filter to estimate contaminant concentrations. A Kalman filter is not a physical filter but rather a mathematical algorithm that can integrate mixed time-series data to make estimates. It is commonly used in various fields, such as traffic prediction and remote sensing.
Using historical data from the Savannah River Site, the researchers found their technique provided reliable information about plume behavior during the last 20 years, indicating the new approach holds significant promise as a long-term monitoring strategy for rapidly assessing a contaminant’s plume stability. According to the researchers, another advantage over conventional approaches is it can reduce the frequency of manual groundwater sampling and lab analysis, and thus reduce the monitoring cost.
Wainwright, who is an expert in groundwater contamination and environmental data analytics, said the methodology can be used for both surface water and groundwater. It can also potentially be used to track other metals, radionuclides, and organic compounds commonly found in groundwater, such as arsenic, chromium, and fuels.