Development of an Automated and User-Friendly Technique for Measuring Dissolved Methane and Nitrous Oxide Concentrations

University Of Rochester, Rochester NY

Investigators

Abstract

This research is fully developing an automated, user-friendly, field-portable, and cost-effective technique for the high-precision analysis of dissolved methane and nitrous oxide concentrations in discrete seawater and freshwater samples. The oceanic and freshwater methane and nitrous oxide systems are large natural reservoirs of these potent greenhouse gases in active exchange with the atmosphere. Numerous hypotheses have been levied suggesting positive feedbacks between increasing ocean temperatures and increasing emissions of these gases. Yet, new and often unexpected production and consumption mechanisms are being discovered and the biogeochemical mechanisms behind these processes are being constrained, suggesting that the dynamics of these systems are not as straightforward as may have originally been hypothesized. While these investigations are diverse spanning local properties to global processes, they are all founded on fundamental measurements of the dissolved concentrations of methane and nitrous oxide. However, a variety of measurement techniques are in use between laboratories which have recently been shown to produce results with substantial interlaboratory variability. The work conducted here is establishing a technique that can be relatively easily implemented into different laboratories measuring these gases for increased precision and interlaboratory comparability of results. Beyond the broad scientific impacts this work will have on the research communities measuring these dissolved gases, this project will also have broad impacts on STEM education. A series of educational modules is being developed to introduce, excite, and educate undergraduate students for technology and instrumentation development in the geosciences, and the modules will be incorporated into a sequence of research courses at the University of Rochester. This project is also supporting graduate and undergraduate students from groups underrepresented in the ocean sciences. High precision analytical chemistry techniques for the quantitative analysis of these molecules must first transfer these gases from the dissolved to gaseous phase. Thus, the technique being developed here incorporates components of both vacuum gas extraction, for increased efficiency, and gas-water equilibration, for increased precision, in a fully automated platform, for increase reproducibility. This project recognizes that most laboratories currently measuring these dissolved gas concentrations likely have one or more of the relatively expensive detectors necessary for these gas-phase analyses. Thus, this project is fully developing a relatively inexpensive “front-end” and freely distributing the automation software, so that this technique can be interfaced with a variety of already available detectors. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.