Subsurface Sampling and Characterization
Characterization of subsurface environmental contamination continues to be an important thrust of the Applied Technology Group, and combines two of its major areas of expertise: sampling and mass spectrometric instrumentation development. In work sponsored by the Departments of Energy and Defense, we have developed several new sampling systems. The passive dual planar membrane organics monitor was an improvement over existing subsurface membrane probes, in that by using very high flow-resistance membranes, the concentrations of contaminants in the enclosed cavity were always independent of the porosity of the strata being sampled.The multisorbent arrayed sampler is a remotely controlled tethered air sampling system for collection and concentration of vadose zone soil gas samples. The device has been demonstrated at DOE's Savannah River and Hanford Sites. The in-situ sparge system is designed to be deployed in groundwater monitoring wells for real time analysis with a direct sampling ion trap mass spectrometer (DSITMS - see below). Water samples can be purged in situ, the volatile contaminants transported to the surface without attendant waste disposal issues.
Over the past decade, our Group has expended considerable effort in designing and deployment of interfaces between commercially available field transportable ion trap mass spectrometers and environmental matrices (air, water, soil). This has led to the development of a technology known as direct sampling ion trap mass spectrometry (DSITMS), by which volatile contaminants in soil and water samples can be purged directly into the mass spectrometer for real time analysis. Air samples can also be directly sampled, or samples pre-concentrated on sorbent media can be desorbed directly into the system. Because of its effectiveness in real time environmental analysis, DSITMS has been mated with the Army Corps of Engineers' Site Characterization and Penetrometer System (SCAPS), a large cone penetrometer truck, at dozens of locations across the United States. The technology has been licensed by ORNL to Tri-Corders Environmental. Years of development effort has recently culminated in the publishing of a new EPA Method, 8265, Volatile Organic Compounds In Water, Soil, Soil Gas, And Air By Direct Sampling Ion Trap Mass Spectrometry (DSITMS). Essentially, this means that the in-field DSITMS methodology can be used as a replacement for slower, laboratory-basedmethods for the quantitative determination of volatile contaminants in environmental matrices.
information, contact Cyril Thompson.
Applied Technology Group R&D