Publications

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This paper describes the development of a surface-acoustic-wave (SAW) sensor that is designed to be operated continuously and in situ to detect volatile organic compounds. A ruggedized stainless-steel package that encases the SAW device and integrated circuit board allows the sensor to be deployed in a variety of media including air, soil, and even water. Polymers were optimized and chosen based on their response to chlorinated aliphatic hydrocarbons (e.g., trichloroethylene), which are common groundwater contaminants. Initial testing indicates that a running-average data-logging algorithm can reduce the noise and increase the sensitivity of the in-situ sensor.

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Groundwater plumes containing dissolved uranium at levels above natural background exist adjacent to uranium ore bodies, at uranium mines, milling locations, and at a number of explosive test facilities. Public health concerns require that some assessment of the potential for further plume movement in the future be made. Reaction-transport models, which might conceivably be used to predict plume movement, require extensive data inputs that are often uncertain. Many of the site-specific inputs are physical parameters that can vary spatially and with time. Limitations in data availability and accuracy means that reaction-transport predictions can rarely provide more than order-of-magnitude bounding estimates of contaminant movement in the subsurface. A more direct means for establishing the limits of contaminant transport is to examine actual plumes to determine if, collectively, they spread and attenuate in a reasonably consistent and characteristic fashion. Here a number of U plumes from ore bodies and contaminated sites were critically examined to identify characteristics of U plume movement. The magnitude of the original contaminant source, the geologic setting, and the hydrologic regime were rarely similar from site to site. Plumes also spanned a vast range of ages, and no complete set of time-series plume analyses based on the spatial extent of U contamination exist for a particular site. Despite the accumulated uncertainties and variabilities, the plume data set gave a clear and reasonably consistent picture of U plume behavior. Specifically, uranium plumes. © 2001 by AEHS.

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