Rapid Advances in Mobile Mass Spectrometry Enhance Tracer Hydrology and Water Management

• Published in: Water resources research 2021-06, Vol.57 (6), p.n/a
• Main Authors: Popp, Andrea L., Manning, Cara C. M., Knapp, Julia L. A.
• Format: Article
• Language: English
• Subjects: Aquatic environment; Biogeochemistry; Dissolved gases; Environmental tracers; Gases; Groundwater; Hazard assessment; Helium; Hydrologic processes; Hydrologic research; Hydrology; Instrumentation; Instruments; Isotopes; Laboratories; Mass spectrometry; Mass spectroscopy; Methods; mobile mass spectrometry; New technology; Oxygen; Rare gases; Sampling instruments; Scientific imaging; Solutes; Spatial discrimination; Spatial resolution; Spectroscopy; Surface water; Time measurement; tracer hydrology; Tracers; Water analysis; Water flow; Water management; Water quality; Water sampling
• ISSN: 0043-1397; 1944-7973
• DOI: 10.1029/2021WR029890

Dissolved gases, including noble gases, are versatile environmental tracers. Historically, the application of dissolved (noble) gases as tracers in hydrology used to be limited because their measurement required expensive, laboratory‐based instrumentation operated by highly trained personnel. Here, we highlight recent advances in mobile mass spectrometry (MS) methods for noble and other dissolved gases, which enable low cost, high‐throughput, real‐time measurements. We also present applications using mobile MS to quantify hydrological and biogeochemical processes in groundwater and surface waters and to assess hazards and risks to aquatic environments. Finally, we indicate potential future applications of these instruments to enhance hydrological research. Plain Language Summary Measurements of hydrological tracers (i.e., specific chemicals or isotopes, whose abundance reflects the properties and history of the sampled water) are an established way to observe how water flows and how solutes might change at and below the Earth’s surface over time. Dissolved gases, including noble (inert) gases such as helium, as well as reactive gases such as oxygen and nitrogen, are effective and versatile hydrological tracers. However, until recently, these measurements typically required large, expensive, laboratory‐based instrumentation operated by highly trained people, which has limited the use of these tracers. Here, we highlight recent advances in instrumentation for dissolved gas measurements that can be deployed in the field and are both less expensive and easier to operate than conventional lab‐based instruments. Thus, this new technology will enable more scientists to conduct dissolved gas measurements and to look at processes with a higher temporal and spatial resolution. We describe different applications where these new methods have helped to study the quantity and quality of water, as well as potential future applications of these methods. Key Points New mobile mass spectrometry (MS) systems enable low‐cost, high‐resolution dissolved gas measurements High‐resolution sampling of dissolved gas tracers can provide new insights into hydrologic processes and systems Combining dissolved gas measurements with other experimental and numerical methods has the potential to further hydrological research