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Located in Scott Rudolph Hall (Earth and Planetary Sciences Building) on the main campus of Washington University in St. Louis, the Stable Isotope Laboratory has been in operation since 1995 under the direction of Dr. Robert Criss. The lab is equipped with a Thermo Finnigan MAT252 mass spectrometer and associated peripheral devices that enable automated sample introduction, traditional dual-inlet, and modern continuous flow analysis.  Results are applied to numerous projects that exploit oxygen, hydrogen and carbon isotopes, but our primary focus has been the investigation of watershed dynamics.  We have generated the most extensive time-series data base available for a major region, an activity that has involved the collection and analysis of several thousand samples of major rivers, surface streams, springs, and meteoric precipitation every year.  Recent published studies address transport and mixing in urban and rural streams, groundwater residence times, variations in annual precipitation, source identification for spring contamination, and the dynamics of flash floods and regional floods.

Our ongoing research efforts have resulted in many new theoretical models that relate discharge, isotopic and chemical variations for rivers and springs. Our published studies of the Missouri River established a new method for defining the sources of individual solutes, and generated novel data that elucidate the response of the huge watershed to major floods and El Nino events.  This work provided the basis for several follow up studies that reinvigorated extensive scientific data on river stages, river geomorphology, and magnetic field variations collected by Lewis and Clark two centuries ago.  Our systematic studies of the Meramec River basin led to the generation of the most detailed geochemical database available for a destructive, fatal flash flood in an unimpounded basin, which became a Federal Disaster area. We also conduct studies of fluids and fluid-rock interactions in deep geologic environments including geothermal areas, fossil hydrothermal systems, and overpressured systems.

The Stable Isotope Laboratory has supported and trained numerous graduate and undergraduate students directly and through opportunities generated by specific grant projects.  Graduate and undergraduate students are currently engaged in self-directed research projects in soil formation and karst environments using carbon isotopes.  Undergraduate projects have included investigations of the influence of diet on fingernail composition and a characterization of the isotope variability of CO2 and dissolved inorganic carbon in springs, cave air, and even beer! Training and advancement of new scientists is an important objective of this facility.

We welcome your interest in the lab and hope that this web site will provide an introduction to our activities. Please contact Dr. Criss with any questions.