Browsing by Author "Jathar, Shantanu H., committee member"
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Item Open Access Air quality implications from oxidation of anthropogenic and biogenic precursors in the troposphere(Colorado State University. Libraries, 2019) Link, Michael F., author; Farmer, Delphine, advisor; Fisher, Ellen R., committee member; Neilson, James R., committee member; Jathar, Shantanu H., committee member; Ravishankara, Akkihebbal R., committee memberOxidation chemistry in the troposphere drives the formation of air pollutants, harmful to human health and the natural world. Emissions from both anthropogenic and biogenic sources control the ways in which air pollution is formed and thus understanding the chemistry of the oxidation of these emissions enhances our ability to predict how air quality evolves in the future. Experiments simulating tropospheric oxidation chemistry on anthropogenic point sources show that identifying unique chemical processes resulting in air pollution allow for a greater specificity in how to pursue strategies for pollution mitigation policy with regional and hemispheric implications. This thesis focuses on the implementation of advancements in instrumentation and experimental techniques to understand how tropospheric oxidation of anthropogenic and biogenic precursors can produce air pollution. First, we subject vehicle exhaust to simulated tropospheric oxidation and quantify the formation of particulate matter and a toxic gas, isocyanic acid. We estimate how important oxidation of vehicle emissions are for these atmospheric pollutants for the South Coast Air Basin of California and the Seoul Metropolitan Region. Second, we investigate the propensity for isoprene to produce formic and acetic acid in laboratory oxidation experiments. We find that isoprene is likely a major source of formic acid in biogenically-influenced environments, however the exact mechanisms for formation remain unclear. Lastly, we use chemical ionization mass spectrometer measurements to quantify the fraction of oxidized carbon allocated to gas-phase organic acids from isoprene oxidation in laboratory experiments. Through comparison with field measurements from a forest in Alabama to a forest in Colorado we determine high levels of isoprene in Alabama are responsible for high levels of organic acids compared to Colorado. We also observe that influences of anthropogenic NOₓ suppress the formation of gas-phase organic acids suggesting as NOₓ levels decrease throughout the US in the future organic acids produced from oxidation from isoprene are likely to increase.Item Open Access Emissions, evolution, and transport of ammonia (NH₃) from large animal feeding operations: a summertime study in northeastern Colorado(Colorado State University. Libraries, 2024) Juncosa Calahorrano, Julieta Fernanda, author; Fischer, Emily V., advisor; Collett, Jeffrey L., Jr., committee member; Pierce, Jeffrey R., committee member; Jathar, Shantanu H., committee memberThe Transport and Transformation of Ammonia (TRANS2Am) airborne field campaign occurred over northeastern Colorado during the summers of 2021 and 2022. TRANS2Am measured ammonia NH3 emissions from cattle feedlots and dairies with the goal of describing the near-field evolution of the NH3 emitted from animal feeding operations. Most of the animal husbandry facilities in Colorado are co-located with oil and gas development within the Denver-Julesburg basin, an important source of methane (CH4) and ethane (C2H6) in the region. Leveraging TRANS2Am observations, this dissertation presents estimates of NH3 emissions ratios with respect to CH4 (NH3 EmR), with and without correction of CH4 from oil and gas, for 29 feedlots and dairies in the region. The data show larger emissions ratios than previously reported in the literature with a large range of values (i.e., 0.1 - 2.6 ppbv ppbv-1). Facilities housing cattle and dairy had a mean (std) of 1.20 (0.63) and 0.29 (0.08) ppbv ppbv-1, respectively. NH3 emissions have a strong dependency with time of day, with peak emissions around noon and lower emissions earlier in the morning and during the evening. Only 15% of the total ammonia (NHx) is in the particle phase (i.e., NH4+) near major sources during the warm summer months. Finally, estimates of NH3 emission rates from 4 optimally sampled facilities range from 4 - 29 g NH3 · h-1 · hd-1. This work also investigates the nearfield evolution of NH3 in five plumes from large animal husbandry facilities observed during TRANS2Am using a mass balance approach with CH4 as a conservative tracer in the timescales of plume transport. Since the plumes in TRANS2Am were not sampled in a pseudo-lagrangian manner, an empirical model is needed to correct for variations in summertime NH3 emissions as a function of local time (LT) (CF = 1.87ln(LT) - 3.95). Results from the mass balance approach show that the average summertime NH3 decay time below 80% and 60% against deposition in plumes from large animal feeding operations is ~1 and ~2 hours, respectively. Additionally, we present estimates of deposition/emission fluxes every 5 km downwind of the plume. We found that deposition almost always happens in the first 10 km from the emission source. Beyond that, the complex environmental exchange of NH3 between the atmosphere and the surface suggests that fresh NH3 emissions from small nearby sources, water bodies, and crops/soil could contribute to sufficient NH3 to switch the direction of the flux (to emission). Large uncertainties still remain in emission and deposition fluxes, shining light on the need for more measurements in the region. To our knowledge, this is the first study presenting NH3 evolution in the atmosphere using a conservative tracer and airborne measurements. The second goal of TRANS2Am was to investigate easterly wind conditions capable of moving agricultural emissions of ammonia (NH3) through urban areas and into the Rocky Mountains. TRANS2Am captured 6 of these events, unveiling important commonalities. 1) NH3 enhancements are present over the mountains on summer afternoons when easterly winds are present in the foothills region. 2) The abundance of summertime gas-phase NH3 is 1 and 2 orders of magnitude higher than particle-phase NH4+ over the mountains and major agricultural sources, respectively. 3) During thermally driven circulation periods, emissions from animal husbandry sources closer to the mountains likely contribute more to the NH3 observed over the mountains than sources located further east. 4) Transport of summertime plumes from major animal husbandry sources in northeastern Colorado westward across the foothills requires ~5 hours. 5) Winds drive variability in the transport of NH3 into nearby mountain ecosystems, producing both direct plume transport and recirculation. A similar campaign in other seasons, including spring and autumn, when synoptic scale events can produce sustained upslope transport, would place these results in context.Item Open Access Integrated techno-economic analysis and life cycle assessment of emerging technologies with temporal resolution(Colorado State University. Libraries, 2020) Sproul, Evan, author; Quinn, Jason C., advisor; Marchese, Anthony J., committee member; Jathar, Shantanu H., committee member; Denning, A. Scott, committee memberTechno-economic analysis (TEA) and life cycle assessment (LCA) are analytical tools used to quantify the economic and environmental performance of emerging technologies. TEA and LCA help guide the development of these technologies by identifying areas where additional research will significantly reduce economic costs and environmental impacts. Although often used in tandem, TEA and LCA output separate results that rely upon disconnected metrics. When considering the impact of time, the disconnect between TEA and LCA methods is critical and can significantly impact results. In this dissertation, three phases of research are conducted to illustrate and reconcile the disconnect between TEA and LCA. In the first phase, standard TEA and LCA methods are used to evaluate the economic and environmental performance of natural rubber derived from guayule (Parthenium argentatum). This evaluation is used to identify the strengths and weaknesses of interpreting disconnected TEA and LCA results. In the second phase, two new methods are created to overcome this disconnect by integrating temporally resolved TEA and LCA. These methods are applied to electric power and guayule rubber production to highlight the impacts of integrating temporally resolved TEA and LCA. In the third phase, integrated TEA and LCA is used to perform a deep-dive evaluation on low-emissions technology options for natural gas combined cycle power plants. In this phase, TEA and LCA with temporal resolution are used to identify cost targets for biomethane, carbon capture and storage (CCS), and bioenergy with CCS (BECCS) under different emissions pricing scenarios. Taken together, the three phases of research in this dissertation represent a wide range of applications and methodologies, each with varying objectives and complexity. Understanding the details of these approaches will help guide future analysis where economic costs, environmental impacts, and time are important considerations in technological development.Item Open Access Preliminary development and testing of an open-path hydrocarbon sensor for oil and gas facility monitoring(Colorado State University. Libraries, 2019) Farris, Betsy M., author; Yalin, Azer P., advisor; Fischer, Emily V., committee member; Jathar, Shantanu H., committee memberWe developed an open-path laser absorption sensor for detection of unspeciated hydrocarbons for oil and gas production facility fence line monitoring. Such sensors can aid in maintaining air quality standards by quantifying greenhouse gas emissions and detecting emissions that cause adverse health effects. Our initial design employs a single-path detection system, though future implementations may use multiple paths for large-scale facility monitoring. The sensor uses a compact mid-infrared laser source in the spectral region of ~3.3 µm to measure absorption of several hydrocarbon species and is intended for open-paths of ~100 m to 1 km. Spectral simulations show that for typical conditions the hydrocarbons cause a transmission reduction of ~10% allowing for a robust measurement. The initial prototype system uses a helium-neon (He:Ne) laser at 3.391 µm for which signal contributions from methane and non-methane hydrocarbons are comparable. Closed-cell tests were performed with diluted methane (~150-250 ppm) to validate the transmission signals and showed good agreement with expected (calculated) values to within ~10%. The system employs a reference leg, with a 2nd detector (near the source), to normalize for laser power fluctuations. For improved signal-to-noise, particularly for detection of small concentrations and transmission changes, we employ phase-sensitive detection with a mechanical chopper and software based lock-in amplifier. This detection scheme, when employed in the field, allows measurement of transmission signals with stability <0.5% (based on coefficient of variation over 60 s). The portable field sensor system uses two refractive telescopes (2" diameter optics), a transmitter and receiver co-located on a mobile optical breadboard, and a reflector dictating the pathlength. We performed initial tests with pathlengths up to ~25 m (one way), though the design should allow paths in excess of 100 m. Methane was released for initial field tests at known flow rates near the center of the beam path. Transmission signals in agreement with expectations (given uncertainties in the wind and plume dispersion) were observed. The system should allow detection of leaks (emissions) for mass flows as low as ~0.1 g/s of methane (or equivalent optical signal from other species resulting in a 1% change in signal) for the case where the source is ~150 m from the beam path and under typical atmospheric conditions. Recommendations for future modifications are provided based on potential shortcomings identified by initial field testing. Initial field testing also proved that this technology could be a viable low-cost solution for hydrocarbon detection.Item Open Access Second-order sub-array Cartesian product split-plot design(Colorado State University. Libraries, 2015) Cortés-Mestres, Luis A., author; Duff, William S., advisor; Simpson, James R., advisor; Chong, Edwin K. P., committee member; Bradley, Thomas H., committee member; Jathar, Shantanu H., committee memberFisher (1926) laid down the fundamental principles of design of experiments: factorization, replication, randomization, and local control of error. In industrial experiments, however, departure from these principles is commonplace. Many industrial experiments involve situations in which complete randomization may not be feasible because the factor level settings are impractical or inconvenient to change, the resources available to complete the experiment in homogenous settings are limited, or both. Restricted randomization due to factor levels that are impractical or inconvenient to change can lead to a split-plot experiment. Restricted randomization due to resource limitation can lead to blocking. Situations that require fitting a second-order model under those conditions lead to a second-order block split-plot experiment. Although response surface methodology has experienced a phenomenal growth since Box and Wilson (1951), the departure from standard methods to tackle second-order block split-plot design remains, for the most part, unexplored. Most graduate textbooks only provide a relatively basic treatise of the subject. Peer-reviewed literature is scarce, has a limited number of examples, and provides guidelines that often are too general. This deficit of information leaves practitioners ill prepared to face the roadblocks illuminated by Simpson, Kowalski, and Landman (2004). Practical strategies to help practitioners in dealing with the challenges presented by second-order block split-plot design are provided, including an end-to-end, innovative approach for the construction of a new form of effective and efficient response surface design referred to as second-order sub-array Cartesian product split-plot design. This new form of design is an alternative to ineffective split-plot designs that are currently in use by the manufacturing and quality control community. The design is economical, the prediction variance of the regression coefficients is low and stable, and the aliasing between the terms in the model and effects that are not in the model as well as the correlation between similar effects that are not in the model is low. Based on an assessment using well-accepted key design evaluation criterion, it is demonstrated that second-order sub-array Cartesian product split-plot designs perform as well or better than historical designs that have been considered standards up to this point.Item Open Access Volatile organic compound concentrations and the impacts of future oil and natural gas development in the Colorado Northern Front Range(Colorado State University. Libraries, 2018) Weber, Derek T., author; Collett, Jeffrey L., advisor; Fischer, Emily V., committee member; Jathar, Shantanu H., committee member; Hecobian, Arsineh, committee memberRecent advances in unconventional extraction of oil and natural gas (O&NG) have caused an increase in the number of wells in the Colorado Northern Front Range (CNFR) which has doubled Colorado's natural gas production over the last 15 years. Increased O&NG activity can lead to increased emissions of Volatile Organic Compounds (VOCs) which may negatively impact air quality and human health. This study looks at five sites (an elementary school, residential area, Fossil Creek Natural Area, Soapstone Natural Area, and a gas station) in Fort Collins and Timnath with the objectives of determining the gradient of VOC concentrations across a subsection of the CNFR, providing a baseline to compare potentially elevated VOC concentrations from future O&NG development, and a better understanding of the influence of O&NG emissions on air quality in the CNFR. Whole air samples were collected at all locations using an evacuated 6L stainless steel canister equipped with a calibrated flow controller that sampled at a constant flow rate for approximately 1 week. Sampling began at the elementary school and gas station in the summer of 2015 and concluded in November of 2016. Sampling at the two natural areas and the residential area took place in the fall of 2015. VOC concentrations were analyzed using an online gas chromatography flame ionization detector (GC-FID) system. An in-situ real-time GC was also deployed along with an All-In-One (AIO) weather station at the residential area providing hourly VOC and meteorological measurements for approximately 3 weeks in the fall of 2015. A suite of 48 VOCs were measured in this study. Ambient concentrations of BTEX compounds (Benzene, Toluene, Ethylbenzene, and Xylenes) are often of particular interest due to their carcinogenic effects and toxicity; therefore, they were studied in-depth as part of this thesis. Benzene was found to have median ambient concentration at the elementary school, residential area, Fossil Creek Natural Area, Soapstone Natural Area, and the gas station of 0.18, 0.14, 0.32, 0.09, and 0.55ppbv, respectively. Through the use of VOC correlations with propane and acetylene and VOC ratios, it was determined that O&NG emissions have a large influence on ambient VOC concentrations in the CNFR. The mean ratio of i-pentane to n-pentane found at the elementary school, residential area, Fossil Creek Natural Area, Soapstone Natural Area, and the gas station was 1.07, 1.17, 1.16, 1.05, and 2.35, respectively. This indicates that the elementary school and Soapstone Natural Area are strongly influence by O&NG emissions while the residential area and Fossil Creek Natural Area have a mixed influence from O&NG activity as well as vehicular emissions. In contrast the gas station, displayed a clear combustion signature, as expected. Additional VOC ratios were utilized; however, i-pentane to n-pentane ratio was determined to be the most robust tool to assess source apportionment in the CNFR. In addition, through the use of meteorological data coupled with the real-time GC VOC measurements, there is strong evidence that local O&NG sources can have a large impact on air quality at the residential area. The OH reactivity at each location was evaluated in order to compare the ozone production potential by the VOCs measured at each site. Fossil Creek NA showed the largest total OH reactivity in the fall while Soapstone NA displayed the lowest. At Soapstone NA, 66.7% of the total OH reactivity resulted from aromatics, which is the highest, and 11.4% resulted from alkenes, which is the lowest compared to each group's contribution at other sites. At the elementary school, 3.2% of the OH reactivity in the summer was attributed to isoprene, whereas in the fall, winter, and spring only 2.0%, 0.41%, and 0.76% of the OH reactivity resulted from isoprene, respectively. Development of new unconventional O&NG wells is ongoing in the CNFR and there are plans to develop wells in close proximity to the elementary school. The American Meteorological Society (AMS)/Environmental Protection Agency (EPA) steady-state dispersion model AERMOD was utilized to project the potential increased concentration of benzene as a result of this development. The model was run utilizing the 5th, 25th, median, 75th, and 95th percentile emission rates of benzene found by a past study at production sites in the CNFR. The annual average concentration increases above background at the school (0.18 ± 0.08ppbv) for the 5th, 25th, median, 75th, and 95th percentile emission rates were found to be 0.0067, 0.11, 0.33, 0.89, and 6.7ppbv, respectively. The strongest benzene enhancement at the school occurred 0:00 (midnight) - 08:00 and 17:00 - 23:00 (0.46ppbv); however, during school attendance hours (08:35 - 15:13) the concentration increase was 0.024ppbv.