USING THE SHENANDOAH VALLEY (AND SURROUNDING AREA) AS A FIELD LABORATORY FOR TEACHING INTRODUCTORY AQUEOUS GEOCHEMISTRY

A class called “Geochemistry of Natural Waters” has been taught at James Madison University for over 35 years. The course began as an elective for Geology majors and enrolled between 6 to 9 students per year. This class is now cross listed in 3 different departments at JMU and enrolls between 40 and 50 students every time it is offered. Student interest in this class has grown, in part, because the course increasingly draws upon the local geology and hydrology to showcase important aqueous geochemical topics and processes that can be studied by collecting and analyzing field and lab data.

Every semester, students work with a variety of water chemistry data collected from the Shenandoah Valley (and surrounding area) that demonstrate important geochemical concepts, data analytical techniques, and or field/lab techniques. Topics, or concepts, recently used in the class include: establishing the source of heat driving thermal spring waters using He³/He⁴ isotopes; using trend analysis of major cations and anions (starting in the 1930’s) to show how streams and rivers have been impacted by changes in land use and urbanization; whether changes in best management practices have an impact on the Chesapeake Bay Total Maximum Daily Load (TMDL) targets; using stable isotopes of hydrogen and oxygen to define a Local Meteoric Water Line and how it compares to the Global Meteoric Water Line; using stable isotopes of sulfur to determine the source of sulfate dissolved in groundwater; using major ion concentrations to show how different lithologies of rocks (including quartzite, shale, dolomite, and limestones) impact; and using water chemistry to determine how resilient (or vulnerable) groundwater resources are in the Shenandoah Valley.

This talk will briefly present background, data sets, and learning objectives for these topics that can be used in an introductory Geochemistry of Natural Waters course.