Several compounds were evaluated in a number of optical configurations in order to test the optical response of these compounds to changes in humidity. Reichardt`s betaine (Reichardt`s dye, ET-30 dye, 2,6-diphenyl-4-(2,4,6-triphenyl-N-pyridinio)phenolate), a solvatochromic molecule, and several vapochromic compounds were tested, and each responded to a wide range of humidity by exhibiting shifts in visible absorption. All compounds in the study suffered from some degree of hysteresis upon humidity cycling. It is unclear as to the mechanism for this hysteresis, but future work will attempt to either model or remove the hysteresis effects. In the case of the vapochromic compounds, the hysteresis may be due to structural changes in the crystal lattice of the solid state compound. A prototype sensor configuration was also developed involving an attenuated total reflectance probe. The future of the project will deal with elucidating the hysteresis mechanisms for each compound, evaluating several other vapochromic compounds, and testing different immobilization schemes for the compounds under study. In addition, several other optical technologies will be investigated for application in optical humidity sensing.

The legacy of nearly five of rapid industrialization throughout the Southwest includes sites where volatile contaminants have been accidentally or intentionally released at or immediately below the surface. Understanding the mechanism and rate of volatile transport trough the vadose zone is important to assessing the potential impact on groundwater resources. This is particularly significant in and environments where the inseminated (vadose) zone above the water table may be more than 300 m thick. While numerical models have been developed to predict the movement of volatiles trough the unsaturated zone, there are only limited opportunities to verify predictions against field data. Field measurements of vadose zone transport are important in terms of constraining model parameters and can be applied to a variety of contaminant issues. This includes the ability to monitor and detect deep underground explosions in violation of nuclear test ban treaties. We have investigated the movement of vadose zone gases in a deep alluvial basin at the Nevada Test Site. The opportunity to study the migration of soil gases in this setting is unique due to the access afforded by the Joint Test Organization`s U-la tunnel complex, mined at a depth of approximately 300 m below ground surface in …

The purpose of this report is to provide the results of the first annual self-assessment to confirm readiness to replace the mixer pump (pump No.1) in Tank 241-SY-101, should the mixer pump fail or need to be replaced for some other reason.