Relative humidity (RH) is an important parameter associated with occupant comfort in buildings. However, the effects of RH on indoor source off-gassing and interactions between air pollutants and indoor materials are poorly understood. For this study, air samples were collected in residential buildings to characterize “background” concentrations of volatile organic compounds (VOCs) in air. The interior space was then humidified for several hours prior to collection of another air sample to characterize the effects of increased RH on VOC concentrations. Samples were analyzed by GC/FID with abundance “binning” by elution time. Some samples were also analyzed using GC/MS to identify specific VOCs. Results indicate that increasing RH is associated with increases in VOC concentrations in residential indoor air. Many of the chemicals that show enhanced off-gassing are associated with architectural coating, moth repellents, and cleaning agents. The results of this study are novel and may have implications with respect to health effects associated with damp buildings and increased respiratory effects of children during sleep in bedrooms with elevated RH. / text

<p> The sulfur cycle is perhaps one of earth's most important cycles. Biologically sulfur is the main constituent needed to form building blocks such as amino acids. Ecologically, it can devastate forests, lakes and ecosystems in one of it's many forms. Industrially (and perhaps naturally) it is the source of our acid rain problem. </p> <p> An estimation of sulfide fluxes emitted into the atmosphere is extremely variant due to the lack of efficient means of measuring these fluxes. Several simplistic measuring devices have been employed to estimate the oceanic, continental and atmospheric fluxes. Problems have arisen due to the non-uniform distribution of sulfur sources such as industries, volcanoes and marshlands. </p> <p> In the specific case estimates of fluxes have of organic volatile been deduced and not sulfides, actually measured to any great extent. The fundamental reason for this being the lack of an efficient means of recording data in the field to support the flux estimates. </p> <p> This study has attempted to secure the efficiency of adsorption tubes used to sample in situ freshwater sulfide fluxes. Optimal preparation involved using Molecular Sieve SA (60/80 mesh) contained and activated in pyrex glass tubing (6mm. o.d.). Proper activation occurred at 300C for 8 hours under a constant helium flow. </p> <p> Adsorption of sulfides was by helium induced release of gases at room/atmospheric temperatures. After 15 minutes, the adsorption tube was recapped and stored at (-8C) for no more than 7 days. At this time, the tubes were analyzed. </p> <p> Analysis was by GC/HECD in the laboratory. A custom made heat desorber (at 270C), in conjunction with liquid nitrogen and hot water sufficiently trapped the released sulfides from the adsorption tube. Calibrated data obtained in the laboratory provided for proper analytical interpretations of the flux of sulfides emitted from the sample. </p> / Thesis / Bachelor of Science (BSc)

The hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hemiptera: Adelgidae), is an invasive pest from Japan that is causing significant hemlock mortality in the eastern U.S. The most promising control method is biological control. Beetles in the genus Laricobius are adelgid specialists. In 2005, Laricobius osakensis, was discovered in Japan and in 2010 was approved for release in the eastern United States and there have now been more than 60 releases. In 2014, the polar vortex resulted in significant HWA mortality in the eastern U.S., depleting the food source for L. osakensis, which resulted in low field recoveries of them. In the 2015-2016 field season, there were 14 larvae recovered from the field, and the 2016-2017 field season yielded 90 larvae. A significant correlation was found between Laricobius beetles recovered and HWA density, between HWA density and plant hardiness zone, and a negative correlation between Laricobius beetles recovered and average tree health. Understanding more about the supercooling point of L. osakensis gave insight to its ability to survive subfreezing temperatures as occurred in 2014. Comparison of the supercooling point between the northern and southern populations of L. osakensis, and to the other released HWA predator, L. nigrinus, will allow us to determine which biological control agent is best suited for release in the coldest regions. The overall mean supercooling points of northern L. osakensis was -13.52 oC, southern L. osakensis was -13.42 oC, and L. nigrinus was -13.57 oC. There were no significant differences between species or populations. / Master of Science in Life Sciences / The hemlock woolly adelgid (HWA) is an invasive insect species from Asia that is the most important pest of eastern and Carolina hemlock trees in the eastern U. S. Laricobius osakensis is a small beetle from Japan that feeds only on HWA, and been released since 2012 in the eastern United States to control HWA populations. It is important to determine if L. osakensis populations were able to survive and spread in the eastern United States, and if the predator has an effect on HWA populations and the health of hemlock trees. In 2014, extreme cold temperatures in Virginia resulted in wide-scale death of HWA populations, depleting the food source for L. osakensis. Consequently, only 17 L. osakensis beetles were found on hemlock trees near release sites; however, the following year, 147 beetles were found. The ability to survive extreme cold temperatures is important for selecting a biological control agent for release in such regions. We can find out information about how tolerant a species is to cold temperatures by determining the supercooling point, the temperature at which it cannot stop itself from freezing. In this study we compared the supercooling points of a northern and southern population of L. osakensis, as well as another previously released and established biological control agent of HWA, Laricobius nigrinus. I found that there was no significant difference in supercooling point between the different types of Laricobius beetles suggesting that none of these species or populations appears to be anymore cold tolerant than the other for release in the colder regions of the U. S.

Volatile Organic Compounds (VOCs) are commonly used as indicators of an organism's health, among other factors. Traditionally, gas chromatographs (GC) are used to classify these but are prohibitively expensive and impractical for field use. This thesis outlines the motivations, design, construction, and characterization of a portable GC. This proof-of-concept uses off-the-shelf components to show that the production of a device is feasible. It was able to successfully generate carrier gas from the surrounding air via filtration by activated carbon fiber filters. It was also able to reliably produce distinguishable peaks for acetone and hexane at retention times that were reasonable for a prototype system. With some modifications, this system has the strong potential for long-term implementation in the field.