The Colorado Northern Front Range Metropolitan Area (NFRMA) regularly exceeds the National Ambient Air Quality Standards (NAAQS) for ozone (O3). This region has a growing urban population and extensive oil and natural gas production from the nearby Wattenberg Gas Field (WGF) in the Denver-Julesburg Basin. In 2015, a large suite (40+ species) of volatile organic compounds were measured using a custom built online multichannel gas chromatography system over 8 weeks in spring and 8 weeks in summer at the Boulder Atmospheric Observatory (BAO). Abeleira et al. (2017) quantified three oxygenated volatile organic compounds (OVOCs): acetone, acetaldehyde, and methyl ethyl ketone (MEK). Abeleira et al. (2017) found that OVOCs accounted for almost a quarter of the OH reactivity yet the source profiles for these compounds were poorly reconstructed by a Positive Matric Factorization (PMF) analysis. Here, we closely examine the abundance of MEK to better understand the different sources of MEK. MEK can be directly emitted and it can also be produced during the atmospheric oxidation of several different hydrocarbons (e.g. n-butane, 3-methylhexane, i-pentane) however these mechanisms are poorly understood. We investigate the dominant photochemical production pathways using a box model, and characterize local and synoptic meteorological conditions with respect to MEK abundance. We find that emissions of light alkanes (e.g. n-butane) are an important component for understanding mixing ratios of OVOCs, specifically MEK, in the NFRMA.
An Environmental History of the CC Ornithological Collection
This thesis will provide background information on the region, explore the cultural and scientific significance of the area, the series of executive actions that have left the monument in limbo, the unique management structure put in place by the Obama administration, the stakeholders who advocated for and against the monument, the law and policy by which BENM was created, the legality of the executive power to modify or revoke a monument, and provide policy and management recommendations that could ensure the protection of the monument moving forward. Through this exploration, it will become apparent that for a number of environmental, cultural, political, and legal reasons BENM should be upheld as it was originally designed by monument proponents and established by the Obama administration.
The stability of the West Antarctic Ice Sheet depends on the buttressing ability of its ice shelves. These ice shelves are threatened by a warming ocean and atmosphere, and if lost due to melting, then the West Antarctic Ice Sheet will face accelerated movement toward the coasts, where melting will contribute to global sea-level rise. The ROSETTA-Ice Project used the ICEPOD instrument suite to collect shallow ice radar profiles of the Ross Ice Shelf that reveal the extent of ice stream and glacier-ice versus accumulation-ice constituents of the shelf. My research focus is on the ice that flowed into the shelf from Kamb Ice Stream. The ice volume can be identified in the shallow ice radar images as a jagged reflection. Distinct repeated features in the reflectors at the top and base of the glacier-ice volume can be tracked from line to line and across the length of the glacier within the shelf. The consistent glacier-ice reflectors of Kamb Ice Stream provide markers for strain, depth variation, and thickness change between flight-line profiles. Once mapped, depth, width, and thickness variations in the glacier-ice volumes can be used to assess the processes responsible for thickness change. Strain is the dominant process verified by prior studies. Our work seeks to isolate and quantify change resulting from basal processes such as melting and freeze-on that could reveal areas of importance for study of ocean-ice interactions in the sub-ice shelf Ross Sea marine cavity. After accounting for vertical strain, an average thinning of Ross Ice Shelf along the Kamb Ice Stream flow is 3.2 meters per decade, attributable to basal melting. Evidence was found for the existence of an ocean current pathway bringing in warmer water underneath the Ross Ice Shelf and creating a basal melt cavity beneath the left margin of Kamb, within approximately 70 km of the front. Basal channels evident in the radar profiles appear to coincide with channel and crevasse locations identified in previous studies. PLEASE NOTE: This thesis is available only by request and will not be viewable by the public until June 1, 2021. All requests to view the thesis before June 1, 2021 must be directed to Christine Siddoway (firstname.lastname@example.org).
Climate change impacts temperature and precipitation regimes which can shift species composition and induce state changes. Disturbance events, which alter the productive capacity of ecosystems, may also shift pre-disturbance stable states to entirely new, alternative stable states. Under scenarios of increased frequency and intensity of disturbances predicted with climate change, state shifts are likely to become more common. In the Intermountain West, interactions between climate change and severe wildfires may decrease forest resilience through forest ecosystem conversion to different tree species assemblages, shrubland or grassland states. Our findings support the notion that current shifts from forest to non-forested vegetation may be underway and that these changes are likely expedited by wildﬁre disturbance. Results indicate that severe wildfire has markedly altered soil OM pools such that burned sites are not only storing significantly less SOM (burned soils contained 77% less C than reference soils) but retaining a significantly smaller fraction of SOM than unburned sites (burned soils retain 4% less DOC, 3.4% less TDN and 3.7% less DON than unburned soils export to the subsurface). Transformation of flow paths in burned landscapes also had cascading effects on nutrient concentrations in streams: DOC and DON concentrations were 50% to 80% higher in burned streams relative to unburned streams. This study shows that even fifteen years postfire, C accumulation, sequestration and transport remain altered, providing further evidence that Ponderosa pine forests in the Intermountain West may transform into a decadal‐scale C source under a more frequent and severe disturbance regime.
People’s urgent needs for clean, safe, and enjoyable living conditions have enabled Nature Education (NE), a form of Environmental Education (EE), to burgeon to meet the needs of the environmental predicament in the People’s Republic of China (PRC). This emergent qualitative study was guided by grounded theory based on data collection and analysis from transcribing and translating 12 in-depth interviews with four case study NE organizations. Building on Integral theory and Maslow’s hierarchy of needs, this study analyzes how cultural perspectives of human-nature relationships contribute to the progression of indigenous environmental education. Based on three cycles of coding and the resulting themes that allowed me to trace the emergence and development of NE in PRC, this study presents a new model, the holarchy of human environmental needs, that includes needs on several levels: survival, resource utilization, social activities, psychological health, to self-actualization. When all levels of environmental needs are met through NE, participants can eventually attain the ultimate harmony with NATURE embodied in Taoism. Within the social context of increasing urban-rural differentiation in PRC, this study also proposes a systematic Experience in nature (EN) network, along with a list of practical suggestion for NE organizations and practitioners to take advantage of community networks, thus raising the efficiency of need-based environmental education.
Previous studies have found treeline dynamics to be related to macroclimatic factors (Harsch et al., 2009) and microclimatic factors such as local snowpack, wind, and air and soil temperature (Germino, Smith, and Resor, 2002; Harsch et al., 2011; Smith et al., 2003). Seedling health has been thought to indicate the future of treeline position (Germino et al., 2002; Smith et al., 2003; Harsch et al., 2011) and has appeared to be highly related to soil temperature (Grace, Berninger, and Nagy, 2002; Harsch et al., 2011; Smith et al., 2003; Körner et al., 2004; Malanson et al., 2011). This study examines the effects of soil temperature on seedling establishment, survival, and growth, and the degree to which soil temperature may influence seedling dynamics relative to other factors. Daytime and nighttime soil temperature, as well as seedling establishment, survival, and growth data, were collected in an abrupt treeline consisting entirely of Engelmann Spruce (Picea engelmannii) on Pikes Peak, Colorado (~3,550 m). The study site was split up into three different microsites with unique microclimates – the Lower Sheltered Zone, Upper Sheltered Zone, and Tundra – where the relationships between seedling dynamics and soil temperatures could be analyzed separately, and post hoc analyses were conducted to compare the broader zonal relationships. Seedling establishment within the Lower Sheltered Zone was generally greater than expected in the warmer areas and less than expected in the colder areas. Establishment in the Tundra, however, followed the opposite pattern. Survival was largely statistically unrelated to soil temperature, unless a certain threshold was surpassed within the Lower Sheltered Zone and Upper Sheltered Zone. Growth was statistically significantly related to daytime soil temperatures within the Lower Sheltered Zone by a second-degree polynomial, with an optimum at 7.87°C (R2 = .39, n = 16, p = 0.04), but statistically unrelated to soil temperatures within the other two zones. Post hoc zonal comparisons of seedling dynamics revealed relatively large statistically significant differences, which suggested that other microclimatic factors were influencing seedling dynamics more than soil temperatures.
Invasive species are becoming increasingly problematic as human activities and climate change accelerate their spread to new areas. The invasive grass Bothriochloa ischaemum (King ranch bluestem) has taken over large portions of the savanna on the Edwards Plateau in central Texas. Given its pervasiveness, it greatly reduces the populations of native grasses and forbs, and land managers are looking for effective ways to control this species. Recurring fire is necessary to maintain savanna ecosystems; this study aims to determine the most effective timing of fire for controlling B. ischaemum and maintaining a diverse savanna ecosystem. An unreplicated randomized block design was used, in which plots were burned at different times of year during 2016, or left unburned as a control. Pre-fire moisture data, soil temperature data from the duration of the burn, and post-fire plant species data were taken from each plot. These data show that there is a non-significant correlation between August burns and higher fire intensity, and a slight negative correlation between fuel moisture content and higher fire intensity. There was a nonsignificant trend towards lower species richness in unburned plots. On average, a plot burned in August or October was less likely to have B. ishcaemum than a plot burned in February or April, or left unburned. Prescribed burns successfully increased the abundance of native perennials, especially when done in the late summer. These results are probably due to differences in plant phenology at the time of each fire. Native plants are adapted to summer fires, while B. ischaemum could be at a vulnerable phenological stage during the summer. These findings have important implications for the management and restoration of central Texas grasslands. We recommend that land managers use prescribed burns during late summer in order to control B. ischaemum and boost ecosystem health.
Anthropogenic emissions in urban areas have the potential to greatly affect the health of people all over the world. However, research has consistently shown that air pollution burdens are highest for low-income populations and communities of color. These studies often use spatially-averaged concentrations measured by surface monitors to represent exposure levels for whole communities, which may potentially lead to bias in exposure estimates. To address this issue, I quantify income- and race-based spatial distribution patterns in of the pollutant nitrogen dioxide (NO2) in Los Angeles, California utilizing NO2 slant columns measured by the Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) airborne instrument. GeoTASO is a newly developed technology with finer spatial resolution compared to conventional methods of data collection (i.e. surface monitors) that can allow for more accurate measurements of NO2 and lead to a better understanding of NO2 distribution inequities. GeoTASO was deployed onboard the NASA UC-12B King Air during three flights each day on June 26 and 27, 2017. We combine GeoTASO observations with income and demographic data at the census tract spatial scale provided by the California Environmental Protection Agency Environmental Health Screening Report. This analysis generally finds higher NO2 associated with higher poverty and majority non-white communities. Communities that were comprised of 80-100% non-white populations had significantly (p < 0.05) higher amounts of NO2 compared to communities with 80-100% white populations, with percent differences ranging from 27-67% between morning and afternoon, respectively. We compare the results obtained with the high-resolution GeoTASO dataset to results derived from an identical analysis using interpolated surface monitor NO2 data and high-resolution land use regression data (LUR) provided by Larkin et al. (2017). We find that the surface monitor observations and LUR predictions underestimate NO2 disparities when compared to GeoTASO. This study shows that using technology with a higher resolution can better capture disparities of NO2 distribution.
Alpine treelines are very unique ecotones which are visibly responding to climate change worldwide. As global climate change persists alpine treelines are expected to migrate into higher elevations. Not all alpine treelines however are uniform and the microclimates created at the surface have seen to be essential for seedling establishment. The particular microclimate along treeline will dictate how heat is distributed which will ultimately control tree survival. This study discusses how wind interacts with treelines when coming from different directions and where areas of sheltering are created. An area of interest was created along treeline on Pikes Peak in Colorado where wind speeds were measured along a transect moving from the forest up to the tundra above. As expected it was found that a large sheltered area of slow air was created when wind moves uphill over the forest. Downhill moving wind shrinks this sheltered area especially during periods of faster wind. Wind parallel to treeline was found to be more turbulent and sensitive to the local spatial structure. As climate change intensifies it is expected that these sheltered zones created by treeline structure will be altered and become more essential for seedling establishment.