Field-Deployable Water Isotope Analyzer for Stream Sampling

DOE is currently responsible for the remediation of 1.7 trillion gallons of contaminated ground water and 40 million cubic meters of contaminated soil generated at over 7000 discrete sites from past weapons production activities. This remediation involves a variety of methodologies including bioremediation, in which substances are injected into the subsurface to enhance microbial decomposition, and natural attenuation, in which natural, unaided processes are used to remediate waste. In order to better understand these remediation processes and maintain site stewardship, recent studies have explored the use of water isotopes (2H/1H and 18O/16O) to study flow paths. Currently, Isotope Ratio Mass Spectrometry (IRMS) is used to measure the stable isotope ratios of water. However, IRMS has several limitations including its need for a dedicated operator, its inability to measure multiple water isotopes simultaneously, and its operational expense. This project will develop a field-deployable analyzer based on cavity-enhanced laser absorption spectroscopy. The analyzer will be capable of continuously quantifying water isotope ratios from a water source without any significant conditioning and will provide isotope ratios to better than 1.0 ¿ in 2H/1H and 0.3 ¿ in 18O/16O, which is sufficient for isotope hydrology studies. Commercial Applications and other Benefits as described by the awardee: The analyzer should be directly useful to the DOE with respect to its need to improve and verify transport models, and to better characterize subsurface flow. The sensor also should find use in environmental research and medical blood diagnostics.