The Environmental Tracer Group evolved during the past decade around both methodology developments and scientific programs. Originally, starting in 1989, the focus of the group was more or less entirely on building the LDEO Noble Gas Laboratory. Emphasis was on terrestrial applications of noble gas studies to a broad spectrum of scientific questions and applications. This effort resulted in the creation of a facility with four modern, all-metal noble gas mass spectrometers described under instruments. The scientific problems studied by noble gases always required inclusion of other tracers such as carbon and oxygen isotopes, or chemical compounds such as CFC's and SF6. Whereas many of these measurements were performed in cooperation with other groups, we established significant measurement capacity in the area of gas chromatography, specifically for CFC's and SF6. Presently, we are adding GC/MS capability to this spectrum of analytical capabilities.
Our analytical facilities include four mass spectrometric systems. Two of these systems are fully automated for large throughput of high-precision tritium and He isotope measurements. The third, semi-automated system is used as a multi-purpose noble gas machine. It is used for measurements of noble gases in groundwater and in rocks (He, Ne, Ar, Kr, and Xe). This system is equipped with two inlet systems: one for water samples and one for rocks (crushers plus high-temperature furnace). A fourth mass spectrometric system for Ar/Ar dating is presently being tested for fully automated measurements.
In addition to the mass spectrometric systems, we also have three gas chromatographic systems. These gas chromatographic system are equipped with electron capture detectors and are used for measurements of deliberately-injected SF6, environmental levels of SF6 in groundwater, and CFC's and SF6 in the atmosphere. Details of the individual analytical systems are listed under instruments.
Members of our group work on a variety of projects including studies of water movement in natural systems (ocean, groundwater), reconstruction of continental paleotemperature records using aquifers as archives, gas exchange between the atmosphere and natural water bodies, and cosmogenic 3He in sediments.