Measurements of noble gas in the atmosphere are a powerful tool to study natural and anthropogenic changes in the Earth system. The chemically inert nature of noble gases means that they are only impacted by physical processes, greatly simplifying the interpretation of observations. Furthermore, fast atmospheric mixing intrinsically integrates global signals on time scales beyond one year allowing local records to capture global changes. Air samples can be obtained in a variety of ways including directly from the atmosphere, from reservoirs intentionally archived by humans, or from small bubbles trapped naturally in ancient ice, enabling the reconstruction of atmospheric changes over a wide range of timescales. However, atmospheric noble gas measurements are challenging because the signals we chase are often small, and analytical methods are still being developed and improved upon. In four chapters, this dissertation aims to deepen our understanding of noble gases as geochemical tracers and highlights new methods and applications of noble gas analyses. Chapter 1 explores the processes that cause small offsets between atmospheric air and air preserved in ice using a 2-D numerical model of air transport through snow. Chapter 2 demonstrates a connection between atmospheric circulation in the upper atmosphere and the in-situ argon-to-nitrogen (Ar/N2) ratio using samples collected by aircraft. Chapter 3 introduces a novel mass spectrometric technique for the precise measurement of small changes in the atmospheric helium abundance and outlines potential scientific applications. Finally, Chapter 4 builds on Chapter 3 and presents the first record of an atmospheric helium build-up which can be linked directly to anthropogenic fossil fuel activity.

The twelve chapters of this volume aim to provide a complete manual for using noble gases in terrestrial geochemistry, covering applications which range from high temperature processes deep in the Earth’s interior to tracing climatic variations using noble gases trapped in ice cores, groundwaters and modern sediments. Other chapters cover noble gases in crustal (aqueous, CO2 and hydrocarbon) fluids and laboratory techniques for determining noble gas solubilities and diffusivities under geologically relevant conditions. Each chapter deals with the fundamentals of the analysis and interpretation of the data, detailing sampling and sampling strategies, techniques for analysis, sources of error and their estimation, including data treatment and data interpretation using recent case studies.

Volume 47 of Reviews in Mineralogy and Geochemistry introduces to Noble Gases. Although the mass spectrometry principles are not complex, the tricks involved in getting better data are often self taught or passed on by working with individuals who themselves are pushing the boundaries further. Furthermore, much of the exciting new science is linked with technical developments that allow us to move beyond the current measurement capabilities. Be they better crushing devices, laser resonance time of flight, multiple collection or compressor sources - the technical issues are central to progress. Contents: Noble Gases – Noble Science An Overview of Noble Gas Geochemistry and Cosmochemistry Noble Gases in the Solar System Noble Gases in the Moon and Meteorites: Radiogenic Components and Early Volatile Chronologies Cosmic-Ray-Produced Noble Gases in Meteorites Martian Noble Gases Origin of Noble Gases in the Terrestrial Planets Noble Gas Isotope Geochemistry of Mid-Ocean Ridge and Ocean Island Basalts: Characterization of Mantle Source Reservoirs Noble Gases and Volatile Recycling at Subduction Zones The Storage and Transport of Noble Gases in the Subcontinental Lithosphere Models for the Distribution of Terrestrial Noble Gases and the Evolution of the Atmosphere Production, Release and Transport of Noble Gases in the Continental Crust Tracing Fluid Origin, Transport and Interaction in the Crust Noble Gases in Lakes and Ground Waters Noble Gases in Ocean Waters and Sediments Cosmic-Ray-Produced Noble Gases in Terrestrial Rocks: Dating Tools for Surface Processes K-Ar and Ar-Ar Dating (U-Th)/He Dating: Techniques, Calibrations, and Applications

In my project, I used the nobles gases (He, Ne, Ar, Kr and Xe) to investigate natural processes occurring in different geodynamical contexts (i.e., subduction, continental collision, rifting), showing how the use of the noble gases is fundamental to constrain the origin of volatiles, and to investigate the Earth interior. Furthermore, I also used these volatiles to recognize the processes (water-gas-rock interaction) that occur during the fluids up rise from the Earth's interior to the atmosphere and quantitatively constrain the extents of these processes. The results of my project are summarized in five main topics: 1) Insights into the degassing history of Earth's mantle from high precision noble gas analysis of magmatic gas 2) Noble Gas and Carbon Isotope Systematics at the Seemingly Inactive Ciomadul Volcano (Romania): Evidence for Volcanic Degassing 3) Mantle-Derived Fluids in the East Java Sedimentary Basin, Indonesia 4) Outgassing of Mantle Volatiles in Compressional Tectonic Regime Away From Volcanism: The Role of Continental Delamination 5) Continental degassing of helium in an active tectonic setting (northern Italy): the role of seismicity.

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Environmental Tracers in Subsurface Hydrology synthesizes the research of specialists into a comprehensive review of the application of environmental tracers to the study of soil water and groundwater flow. The book includes chapters which cover ionic tracers, noble gases, chlorofluorocarbons, tritium, chlorine-36, oxygen-18, deuterium, and isotopes of carbon, strontium, sulphur and nitrogen. Applications of the tracers include the estimation of vertical and horizontal groundwater velocities, groundwater recharge rates, inter-aquifer leakage and mixing processes, chemical processes and palaeohydrology. Practicing hydrologists, soil physicists and hydrology professors and students will find the book to be a valuable support in their work.

This book reviews all the major research accomplishments and summarizes the different applications of radon. It serves as a solid reference book for researchers who are interested in the U-series radionuclides and noble gases as tracers and chronometers. Radon has been widely utilized as a powerful tracer to quantify a number of processes that include gas exchange rates between air and water, submarine groundwater discharge in coastal waters, water exchange between rivers and lakes, ocean circulation, hydrocarbon and uranium exploration. It is also used as an atmospheric tracer for the identification and quantification of air masses and as a tool for earthquake prediction, etc. A significant portion of the book presents state-of-the knowledge on indoor-radon-related health issues. Applications of the decay-series of Rn-222 are presented in a chapter. It serves as a reference and a state-of-the-art resource for researchers who want to learn the different applications of radon in Earth systems.