Alan Seltzer, UCD. An overview of how geochemical tracers in groundwater preserve physical signals set during recharge and its application.

The talk will include a conceptual overview of how geochemical tracers in groundwater preserve physical signals set during recharge, as well as several case studies focused specifically on dissolved gas tracers with wide ranging applications. These case studies include reconstruction of past environmental and climatic information using inert gases in fossil groundwater, tracing the origin and mechanisms of emplacement of offshore freshened groundwater on the New England Shelf, and finally a forward view of how these tracers can be used in both in-situ and lab-based studies focused on applied hydrogeological studies such as tracing groundwater recharge sources (e.g., alternatives to dye tracing) and as a new quantitative tool to understand the sources and fate of nitrate in groundwater systems.