Mountain Scholar :: Browsing by Author "Jathar, Shantanu, committee member"

Browsing by Author "Jathar, Shantanu, committee member"

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Open Access
A low-cost monitor for simultaneous measurement of fine particulate matter and aerosol optical depth
(Colorado State University. Libraries, 2018) Wendt, Eric, author; Volckens, John, advisor; Jathar, Shantanu, committee member; Yalin, Azer, committee member; Pierce, Jeffrey, committee member
Exposure to airborne particulate matter with diameters less than 2.5 µm (PM2.5) is a leading cause of death and disease globally. In addition to affecting health, PM2.5 affects climate and atmospheric visibility. NASA currently uses satellite imaging technology to measure particulate matter air pollution across the world. Satellite image data are used to derive aerosol optical depth (AOD), which is the extinction of light in the atmospheric column. Although AOD data are often used to estimate surface PM2.5 concentration, there is considerable uncertainty associated with the relationship between satellite-derived AOD and ground-level PM2.5. Instruments known as Sun photometers can measure AOD from the Earth's surface and are often used for validation and calibration of satellite data. Reference-grade Sun photometers generally do not have co-located PM2.5 measurements and are too expensive to deploy in large numbers. The objective of this work was to develop an inexpensive and compact integrated PM2.5 mass and AOD sampler known as the Solar-Powered Aerosol Reference Calibrator (SPARC). PM2.5 is sampled using an ultrasonic pumping system, a size-selective cyclone separator, and a filter. Filter measurements can be used to correct the output from a low-cost direct-reading PM2.5 sensor housed within the SPARC. AOD is measured using optically filtered photodiodes at four discrete wavelengths. A suite of integrated sensors enable time-resolved measurement of key metadata including location, altitude, temperature, barometric pressure, relative humidity, solar incidence angle and spatial orientation. The AOD sensors were calibrated relative to a reference monitor in the Aerosol Robotics Network (AERONET). Field validation studies revealed close agreement for AOD values measured between co-located SPARC and AERONET monitors and for PM2.5 mass measured between co-located SPARC and EPA Federal Reference Method (FRM) monitors. These field validation results for this novel monitor demonstrate that AOD and PM2.5 can be accurately measured for the evaluation of AOD:PM2.5 ratios.
Open Access
A study of fumed silica particle deagglomeration associated with instrument sampling techniques and A comparison of NIOSH 7402 and the Tsai Diffusion Sampler for collecting and analyzing carbon nanotubes
(Colorado State University. Libraries, 2018) Khattak, Jared, author; Tsai, Candace Su-Jung, advisor; Reynolds, Stephen, committee member; Jathar, Shantanu, committee member
Accurate characterization of contaminant exposures is critical in ensuring worker safety. Worker exposures are commonly characterized by area monitoring and personal samples. This research includes two parts, which study real time instrument measurements and personal sampling methods for exposure assessment. Real time instruments (RTIs) are used to assess concentrations of airborne particles in manufacturing facilities. These instruments often contain a cyclone, and previous studies have shown that the cyclone may cause measurement variations by dispersing agglomerated particles. This mechanism is thought to increase particle concentrations and decrease particle size. To determine the cyclone effect in this study, three RTIs were evaluated; the scanning mobility particle sizer (SMPS), fast mobility particle sizer (FMPS), and the optical particle sizer (OPS). The SMPS and FMPS contain a cyclone, the OPS does not. Nanoparticles were generated and sampled through pouring and automatic stirring inside a glovebox enclosure. After particles were generated, the glovebox was thoroughly cleaned and measurements were taken in the glovebox. For both generation methods, the SMPS and FMPS recorded an average concentration of 1.2 x 103 particles/cm3 and 1.7 x 104 particles/cm3 more after runs where the cyclone was used than when the cyclone was not used. The OPS, which does not contain a cyclone, recorded minimal differences during the measurement period after the glovebox was cleaned when the cyclone was used and not used on the other instruments. This result indicated that the measured nanoparticle concentrations increased with cyclone use. The results of this study indicate that the cyclone does influence the concentrations recorded by RTIs, and should be cleaned to ensure accurate measurements. The personal sampling methods evaluated were the NIOSH 7402 method for collecting and analyzing Carbon Nanotubes (CNTs) and the Tsai Diffusion Sampler (TDS) method for sampling CNTs. To evaluate each sampling method, CNTs were generated in a small enclosure inside of a glovebox; CNTs were generated by manual stirring. RTIs also sampled during each experiment to provide an estimate of airborne CNT concentrations. Airborne concentrations were estimated using the particle counts from TEM grid samples prepared using both methods. The majority of CNT structures collected by the TDS were individual fibers and clusters smaller than one micron in diameter. The NIOSH 7402 sampler primarily collected larger agglomerates, with the majority of collected particles being larger than two microns in diameter. The average estimated airborne concentrations calculated from the TDS and 7402 method particle counting were 5,200 fibers/cm3 and 59 fibers/cm3 respectively. During the experiments the SMPS recorded an airborne concentration of 1,100 particles/cm3 and the OPS measured an airborne concentration of 33 particles/cm3. Because the concentrations measured by the RTIs significantly exceeded the estimated concentrations derived from the NIOSH 7402 method, it is recommended that the TDS sampler be used as the concentrations derived from this sampler would warrant a more conservative approach to worker safety.
Open Access
Aerosol size distribution changes in FIREX-AQ biomass burning plumes: the role of plume concentration on coagulation and OA condensation/evaporation
(Colorado State University. Libraries, 2022) June, Nicole, author; Pierce, Jeffrey, advisor; Kreidenweis, Sonia, committee member; Jathar, Shantanu, committee member
The evolution of organic aerosols and aerosol size distributions within smoke plumes are uncertain due to the variability in rates of coagulation and organic aerosol (OA) condensation/evaporation across different smoke plumes and potentially in different locations within a single plume. We use aircraft data from the western US portion of the FIREX-AQ campaign to evaluate differences in aerosol size distribution evolution (growing by 10s to over 100 nm in several hours), OA mass, and Oxygen to Carbon ratios (O:C) under different concentrations and amounts of dilution. The observations show diameter increasing more quickly in more concentrated plumes despite these plumes generally having more OA evaporation than in the less concentrated plumes. Initial observations of OA and O:C suggest that evaporation and/or secondary OA formation between emission and the first measurement is also influenced by plume concentration. We estimate the isolated role of coagulation on size changes using model simulations, and we estimate the role of OA condensation/evaporation on size changes using the observed time evolution of the observed OA enhancement. We find that coagulation alone explains the majority of the diameter growth in the transect averages, with more growth occurring in plumes with higher initial number and OA concentrations. Overall, for each of the smoke plumes analyzed, including OA evaporation/condensation has a relatively minor impact on the simulated diameter compared to the changes due to coagulation. Additionally, we examine differences in evolution between the dilute and concentrated sections of the plume based on CO concentration to expand the range of plume concentrations represented in the observations. To determine if these in-plume concentration gradients could be used to understand smoke plumes outside of the range of the sampled average concentration, we simulate the dilute and concentrated plume regions independently (no mixing). In these simulations of each smoke plume region, the model underestimates particle growth in the less-concentrated regions of the plume and overestimates particle growth in the more-concentrated regions. This poor comparison suggests that turbulent mixing between the more- and less-concentrated regions is occurring on timescales too fast for the regions to evolve independently, but slow enough that aerosol size differences are still seen between the regions. The mixing in the plume limits the ability for our conclusions on variations in growth and condensation/evaporation within a plume to be applied to other plumes of a similar concentration. Overall, we conclude that coagulation dominates growth with plume concentrations being important in determining how much coagulational growth is observed.
Open Access
Atmospheric and air quality implications of C2-C5 alkane emissions from the oil and gas sector
(Colorado State University. Libraries, 2018) Tzompa Sosa, Zitely Asafay, author; Fischer, Emily, advisor; Kreidenweis, Sonia M., committee member; Pierce, Jeffrey, committee member; Jathar, Shantanu, committee member
Emissions of C2-C5 alkanes from the U.S. oil and gas sector have changed rapidly over the last decade. This dissertation quantifies the role of the oil and gas sector on light alkane emissions and abundances at local, regional, and global scales. First, we present an updated global ethane (C2H6) emission inventory based on 2010 satellite-derived CH4 fluxes with adjusted C2H6 emissions over the U.S. from the National Emission Inventory (NEI 2011). We contrast our global 2010 C2H6 emission inventory with one developed for 2001. The C2H6 difference between global anthropogenic emissions is subtle (7.9 versus 7.2 Tg yr-1), but the spatial distribution of the emissions is distinct. In the 2010 C2H6 inventory, fossil fuel sources in the Northern Hemisphere represent half of global C2H6 emissions and 95% of global fossil fuel emissions. Over the U.S., un-adjusted NEI 2011 C2H6 emissions produce mixing ratios that are 14-50 % of those observed by aircraft observations (2008-2014). When the NEI 2011 C2H6 emission totals are scaled by a factor of 1.4, the GEOS-Chem model largely reproduces a regional suite of observations, with the exception of the central U.S., where it continues to under- predict observed mixing ratios in the lower troposphere. Second, we use a nested GEOS-Chem simulation driven by updated 2011NEI emissions with aircraft, surface and column observations to 1) document spatial patterns in the emissions and observed atmospheric abundances of C2-C5 alkanes over the U.S., and 2) estimate the contribution of emissions from the U.S. oil and gas industry to these patterns. The oil and gas sector in the updated 2011NEI contributes >80% of the total U.S. emissions of C2H6 and propane (C3H8), and emissions of these species are largest in the central U.S. Observed mixing ratios of C2-C5 alkanes show enhancements over the central U.S. below 2 km. A nested GEOS-Chem simulation underpredicts observed C3H8 mixing ratios in the boundary layer over several U.S. regions and the relative underprediction is not consistent, suggesting C3H8 emissions should receive more attention moving forward. Our decision to consider only C4-C5 alkane emissions as a single lumped species produces a geographic distribution similar to observations. Due to the increasing importance of oil and gas emissions in the U.S., we recommend continued support of existing long-term measurements of C2-C5 alkanes. We suggest additional monitoring of C2-C5 alkanes downwind of northeastern Colorado, Wyoming and western North Dakota to capture changes in these regions. The atmospheric chemistry modeling community should also evaluate whether chemical mechanisms that lump ≤ C6 alkanes are sufficient to understand air quality issues in regions with large emissions of these species. Finally, we investigate the contribution of C2-C5 alkane emissions from the U.S. oil and gas industry to O3 abundances at regional and global scales. Emissions of C2-C5 alkanes from the oil and gas sector make the largest contribution to ozone (O3) production over the central U.S. compared to other regions. The Colorado Front Range is the 8-hour O3 non-attainment area with the highest summertime daytime average O3 enhancement attributed to the U.S. oil and gas sector. The global tropospheric contribution of C2-C5 alkane emissions from the U.S. oil and gas sector to the O3 burden is 0.5 Tg for the year 2011, which represents 0.27% of the Northern Hemisphere tropospheric O3 burden.
Open Access
Atmospheric processing of chemical compounds and direct measurements of particle loss by dry and wet deposition
(Colorado State University. Libraries, 2019) Emerson, Ethan Walker, author; Farmer, Delphine, advisor; Neilson, James, advisor; Ravishankara, A. R. Ravi, committee member; Borch, Thomas, committee member; Barisas, George, committee member; Jathar, Shantanu, committee member
Anthropogenic pollutants, like NOₓ and black carbon (BC), are ubiquitous in the atmosphere and impact human health and the climate. Understanding the atmospheric fate of such pollutants is critical in understanding their impact. This work focuses on understanding the loss of two key pollutants: the chemical termination of gas phase NO and NO₂ (NOₓ) and the deposition of refractory black carbon (rBC) particles. Additionally, because the tools to analyze particle fluxes and coated rBC are lacking, this work describes the development of software to analyze particle fluxes and estimate the thickness of organic coatings on rBC. Removal of aerosols from the atmosphere occurs via wet and dry deposition. Black carbon (BC) is one form of aerosol that impacts atmospheric temperature, cloud formation and properties, the albedo of snow and ice surfaces, and the timing of snowmelt. Parameterization of BC dry deposition is particularly limited due to the lack of available instrumentation for measuring the process, and thus there is a lack of observational datasets with which to evaluate existing models. We present observations of dry and wet deposition rates of size-resolved coated rBC and total aerosol number by eddy covariance technique using a single particle soot photometer (SP2; Droplet Measurement Technologies Inc.) and ultra high sensitivity aerosol spectrometer (UHSAS; Droplet Measurement Technologies Inc.) from the remote Southern Great Plains ARM Climate Research facility in north-central Oklahoma. Using these data, we show that (1) wet deposition dominates the removal of rBC from the atmosphere, (2) dry deposition measurements agree with sophisticated deposition parameterizations, and (3) a simple parameterization adequately describes size-resolved deposition. We assess the implications of this parameterization in GEOS-Chem. Size-resolved deposition schemes, such as those used in current chemical transport models use schemes that have not been compared to recent measurements. Using aggregated deposition velocities from literature observations and those collected by our group, we show that the current scheme used in chemical transport models does not accurately describe observed deposition velocities. Highly sophisticated leaf level models can accurately describe the aggregated observations, but they are ill-suited to global chemical transport models. We present a simple scheme that reasonably describes size-resolved particle deposition in a simple sectional scheme that includes atmospheric parameters. The result of this update is substantial changes in particle concentrations across the globe and these impact cloud condensation nuclei, the direct and indirect effects, and PM2.5 concentrations. NOₓ is a key pollutant that propagates atmospheric chemistry through the coupled HOₓ-NOₓ cycle. Trace gas measurements from the 2015 spring and summer SONGNEX campaign conducted at the Boulder Atmospheric Observatory (BAO) in Northern Front Range Metropolitan Area of Colorado (NFRMA) are characteristic of environment impacted by oil and natural gas, agricultural operations, traffic, biogenic, and urban sources. Using a previously published PMF analysis of volatile organic compounds, we show the impact of a changing atmospheric composition due to emissions from anthropogenic sources on NOx sinks and the implications of HOₓ-NOₓ propagation through box modelling. These results indicate that the NFRMA is sensitive to NOₓ and VOC mixing ratios during spring, summer, and smoke-impacted periods.
Open Access
Atmospheric reactive nitrogen in Rocky Mountain National Park
(Colorado State University. Libraries, 2018) Shao, Yixing, author; Collett, Jeffrey L., advisor; Schumacher, Russ, committee member; Jathar, Shantanu, committee member; Benedict, Katherine, committee member
The Front Range urban corridor in Colorado, located east of Rocky Mountain National Park (RMNP), includes a variety of urban sources of nitrogen oxides, while high emissions of ammonia are found in agricultural sources on the eastern plains of Colorado. The spatial distribution and temporal variation of ammonia and other reactive nitrogen species in the region is not well characterized. Periods of upslope flow can transport atmospheric reactive nitrogen from the Front Range and eastern Colorado, contributing to nitrogen deposition in the park. Deposition of excess atmospheric reactive nitrogen in Rocky Mountain National Park poses threats to sensitive ecosystems. It is important to characterize temporal variation and spatial distribution of reactive nitrogen in the region to better understand the degree to which emission sources in the northeastern plains of Colorado impact RMNP and how meteorological conditions are associated with transport of ammonia to the park. Mobile and in-situ measurements of reactive nitrogen gases and particles were made between 2015 and 2016 in northeastern Colorado and RMNP. Gaseous ammonia was measured with high-time resolution instruments (a Picarro cavity-ring down spectrometer and an Air Sentry ion mobility analyzer); 24-hr integrated concentrations of trace gases and PM2.5 chemical composition in RMNP were measured by URG denuder/filter systems coupled with lab analysis; wet nitrogen deposition was collected with an automated precipitation collector followed by lab analysis. Model outputs from The Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT) was also included for examining transport of ammonia source plumes. Diurnal and seasonal variability of ammonia concentrations and some other reactive nitrogen species were characterized with high time-resolution measurement data. Repeating diurnal cycles were found in Greeley and RMNP. Ammonia concentrations usually increase in the morning and reach maxima around noon in RMNP, while at Greeley ammonia builds up during the night followed by a rapid decrease after sunrise. A seasonal pattern of ammonia levels was also revealed, with higher concentrations observed during summer. When combined with wind data it is clear that elevated ammonia levels in RMNP were associated with easterly transport from the eastern plains of Colorado. The median daily averaged ammonia concentrations measured in Greeley, Loveland and RMNP are 26.2 ppb, 6.3 ppb and 1.1 ppb respectively. Considerable ammonia variability was found in NE Colorado with higher concentrations measured close to CAFOs and source regions. This was particularly clear in mobile NH3 observations where distinct plumes of ammonia were observed away from confined animal feeding operation (CAFOs) sources. Spatial variations, particularly in the north-south direction, were observed to be strongly dependent on meteorology as highlighted by HYSPLIT back trajectories. This study also evaluates the pilot Early Warning System which informs agricultural producers of impending upslope events that are likely to transport nitrogen from eastern Colorado to the park, so that management practices may be implemented to reduce nitrogen emissions. The performance of the meteorological forecasting was evaluated using continuous measurements of atmospheric ammonia concentrations in the RMNP, as well as the wet nitrogen deposition data from 2015. It was found that the model showed skill in capturing some large wet nitrogen deposition events in the park.
Open Access
Composition of fine particles in Carlsbad Caverns National Park and implications for sources and visibility impacts
(Colorado State University. Libraries, 2022) Naimie, Lillian E., author; Collett, Jeffrey L., advisor; Benedict, Katherine B., committee member; Fischer, Emily V., committee member; Jathar, Shantanu, committee member
The Carlsbad Caverns Air Quality Study (CarCavAQS) was designed to examine the influence of regional sources, including urban emissions, increased oil and gas development, wildfires and other biogenic sources, and soil dust on the park, including impacts on fine particle haze, ozone, and nitrogen deposition. Field measurements of aerosols, trace gases, and deposition were conducted from 25 July through 5 September 2019. Here the focus is on observations of the composition and concentration of fine particles and key trace gas precursors to understand important contributing species, their sources, and associated impacts on haze. Measurements focused on fine particulate matter (PM2.5) including mass, major ions, water soluble organic carbon (WSOC), and black carbon (BC) from various high time-resolution instruments as well as an Interagency Monitoring of Protected Visual Environments (IMPROVE) sampler. Supplemental measurements included denuder-filter pack sampling for inorganic gases (HNO3 and NH3) and a Picarro cavity ring down spectrometer for methane (CH4). High-time resolution (6-minute) PM2.5 mass ranged up to 31.8 μg m−3, with an average of 7.67 μg m−3. The main inorganic ion contributions were sulfate (avg 1.3 μg m−3), ammonium (avg 0.30 μg m−3), calcium (Ca2+) (avg 0.22 μg m−3), nitrate (avg 0.16 μg m−3), and sodium (avg 0.057 μg m−3). The WSOC average concentration was 1.2 μg C m−3. Inorganic ion concentrations had significant, sharp spikes in Ca2+, consistent with local dust generation and transport. Ion balance analysis suggests one period of acidic aerosol, the importance of ammonium and calcium in neutralizing sulfate, and significant reactions of nitric acid with sea salt and soil dust. The sums of PILS ion and WSOC concentrations, the latter multiplied by a factor of 1.8 to account for elements other than carbon, were not enough to reach mass closure with the TEOM PM2.5 mass concentrations, suggesting that insoluble species are also an important component of the aerosol at CAVE. IMPROVE sampler data, including insoluble species had good agreement between total PM2.5 mass and speciated PM2.5 aerosol mass. Sulfate is the major contributor to modeled light extinction in the 24-hour IMPROVE data set. Higher time resolution data had periods of significant light extinction from black carbon as well as sulfate, with a maximum 1-hour extinction value of 90 Mm−1. Analysis of transport patterns indicated clear enrichment of sulfate, BC, and CH4 during periods when transport came from the southeast, the direction of greatest abundance of oil and natural gas development. Air masses transported from the northeast, a region of high agricultural activity, were enriched in ammonia.
Open Access
Corrosion testing of alloys for biomass cookstove combustors
(Colorado State University. Libraries, 2017) Banta, Kelly, author; Marchese, Anthony, advisor; Mizia, John, committee member; Jathar, Shantanu, committee member; Sambur, Justin, committee member
Worldwide, over 3 billion people use biomass for cooking and heating. Many people cook over 3-stone fires or inefficient and highly polluting traditional cookstoves, presenting a large human health risk and significant climate impacts. One solution to this is the development of improved cookstoves, which can alleviate this burden by being more efficient and cleaner-burning. To be effective in their purpose, improved cookstoves must be long-lasting. Achieving longevity is challenging from a material corrosion perspective, particularly in the case of metallic combustors, because cookstove combustors must operate at high temperatures (> 600 deg. C) in environments with corrosive species released from biomass combustion. A key part of this challenge is cost, since materials must be inexpensive to permit widespread adoption in the developing world; however, corrosion resistant materials are typically costlier. In this work, screening protocols for corrosion testing of cookstove combustor materials were developed and shown to be effective methods for accelerated corrosion testing, and a number of alloys were evaluated for corrosion performance. Additionally, a FeCrSi alloy was identified as a potentially low-cost material with high corrosion resistance in cookstove applications. This alloy is currently being patented.
Open Access
Dedicated exhaust gas recirculation applied to a rich burn industrial natural gas engine
(Colorado State University. Libraries, 2020) Van Roekel, Chris, author; Olsen, Daniel B., advisor; Jathar, Shantanu, committee member; Marchese, Anthony, committee member; Young, Peter, committee member
Rich burn natural gas engines provide power for industrial applications such as gas compression. In this application where exhaust oxides of nitrogen (NOx) requirements can be critical, rich burn engines offer best in class aftertreatment emission reduction and operating cost capabilities by using a non-selective catalyst reduction (NSCR) or three-way catalyst system. However, due to high combustion temperatures associated with near stoichiometric air-fuel ratio (AFR) operation, rich burn engines are limited in brake mean effective pressure (BMEP) by combustion temperature. Consumers in the gas compression application are left to choose between engines that are capable of meeting even the most stringent emission requirements (rich burn) and engines with high BMEP rating (lean burn). Charge dilution by way of excess air (lean burn) or exhaust gas recirulation (EGR) is a common method used to lower combustion temperature with the purpose of limiting the production of engine out NOx. Conventional configurations of EGR consist of high pressure loop (HPL) and low pressure loop (LPL), each of which rely on components exposed to relatively high temperatures to control the impact that EGR has on combustion. Dedicated EGR is a novel variant of conventional EGR configurations which allows for the impact that EGR has on combustion to be controlled by components exposed to ambient temperature natural gas while also lowering rich burn combustion temperatures. Due to the lack of published research on dedicated EGR applied to industrial natural gas engines and consumer driven need for technologies to increase rich burn industrial natural gas engine BMEP this work represents an initial investigation into challenges associated with and capabilities of dedicated EGR. A Chemkin chemical kinetics model using the SI Engine Zonal, Flame Speed Calculator, and Equilibrium models was developed to quantify dedicated cylinder exhaust composition, laminar flame speed, and equilibrium combustion composition, respectively. The Aramco 2.0 mechanism was used for natural gas kinetics and was modified to include Zel'dovich mechanism for NOx formation. Engine experiments were conducted using a Caterpillar G3304 rich burn natural gas engine modified to operate with and without dedicated EGR. Initial tests that included power sweeps at fixed dedicated cylinder AFR revealed that operating conditions appropriate for dedicated EGR gasoline engines were not suitable for dedicated EGR natural gas engines. A response surface method (RSM) optimization was performed to find improved operating conditions at part load, 3.4 bar BMEP. Results showed that advanced spark timing and slightly rich dedicated cylinder AFR were optimal to achieve decreased coefficient of variance of indicated mean effective pressure (COV IMEP) and balanced cylinder IMEP output. In order to assess how operating with dedicated EGR would affect the performance of a NSCR system at 6.7 bar BMEP and fixed operating conditions engine AFR was swept between rich and lean conditions to quantify catalyst reduction efficiency and find the emissions compliance window. Without intentional AFR dithering the emissions compliance window was increased significantly. Finally, using best operating conditions from the RSM optimization and engine AFR sweep tests engine BMEP was increased beyond the 6.7 bar rating to find the possible increase in power density resulting from dedicated EGR.
Open Access
Development and validation of an outdoor low-cost smoke monitor
(Colorado State University. Libraries, 2017) Kelleher, Scott, author; Volckens, John, advisor; Jathar, Shantanu, committee member; Anderson, Georgiana Brooke, committee member; Pierce, Jeffrey, committee member
Wildfires and prescribed fires produce emissions that are harmful to human health. These health effects, however, are difficult to quantify, likely in part due to sparse data on exposure. The ability to measure fire emissions as they reach sensitive areas is critical to ensuring the protection of public health. Ground level quantification of smoke from wildfires and prescribed fires has proven to be a difficult task. The state of the art for monitoring outdoor air quality has long relied upon expensive, cumbersome equipment that generally requires line power. Few ground-based measurements are typically made during fire events, which limits our ability to quantify and assess the impact of smoke from fire events. The objective of this work was to develop and validate a new type of outdoor air quality monitor, the Outdoor Aerosol Sampler (OAS). The OAS is an active, filter-based air sampler that has been miniaturized and weatherproofed. The OAS represents and attempt to address the technical limitations of field sampling with a device that is relatively inexpensive and independently powered. Prototype development of the OAS was made possible through low-cost electronics, open-source programming platforms, and in house fabrication methods. An online PM2.5 sensor was selected and integrated with the OAS. A Monte Carlo simulation aided in the selection of battery and solar power necessary to independently power the OAS, while keeping cost and size to a minimum. Cellular communications established via Short Message Service (SMS) technology were utilized in transmitting online sensor readings and controlling the OAS remotely. Numerous OAS were deployed to monitor smoke concentrations downwind from a large prescribed fire. Mass concentrations sampled from the burn were interpolated to depict smoke concentration gradients downwind of the fire. Field tests found OAS solar charging efficiency (6.7%) to be slightly less than model input efficiency (7.5%). Outdoor urban testing of the OAS demonstrates moderate agreement with equivalent federal reference method samplers for gravimetric analysis of PM2.5.
Open Access
Development of a combustion system for fecal materials
(Colorado State University. Libraries, 2017) Flagge, Maxwell, author; Marchese, Anthony, advisor; Mizia, John, committee member; Jathar, Shantanu, committee member; Magzamen, Sheryl, committee member
CSU is working with Research Triangle Institute on the Reinvent the Toilet Challenge (RTTC) to develop a fecal matter combustion system. The proposed system will dry, pelletize and combust fecal matter from a community bathroom in a net zero energy consumption process. This technology has the potential to reduce disease by improving sanitation in rural villages that lack modern plumbing. This research is aimed at helping the 2.5 billion individuals in the world who lack modern plumbing and sanitation facilities. Many villages have nothing more than a concrete pit for defecation, and some individuals have no alternative to open defecation, which creates a huge potential for disease transmission. If individuals could safely burn away their fecal material without using any external energy or resources, the instances of sanitation-related disease could be greatly reduced. In this project, CSU's primary tasks are the optimization and automation of fecal combustion technology. The current combustor design is a modified continuous feed downdraft gasifier. Through a series of tests and measurements, several modifications and improvements have been made to the combustor and its control system, allowing the system to burn fecal materials cleanly and efficiently, while ensuring the destruction of any disease-causing pathogens or bacteria.
Open Access
Economic and environmental evaluation of emerging electric vehicle technologies
(Colorado State University. Libraries, 2023) Horesh, Noah, author; Quinn, Jason, advisor; Bradley, Thomas, committee member; Jathar, Shantanu, committee member; Willson, Bryan, committee member
As the transportation sector seeks to reduce costs and greenhouse gas (GHG) emissions, electric vehicles (EVs) have emerged as a promising solution. The continuous growth of the EV market necessitates the development of technologies that facilitate an economically comparable transition away from internal combustion engine vehicles (ICEVs). Moreover, it is essential to incorporate sustainability considerations across the entire value chain of EVs to ensure a sustainable future. The sustainability of EVs extends beyond their usage and includes factors such as battery production, charging infrastructure, and end-of-life management. Techno-economic analysis (TEA) and life cycle assessment (LCA) are key methodologies used to evaluate the economic and environmental components of sustainability, respectively. This dissertation work uses technological performance modeling combined with TEA and LCA methods to identify optimal deployment strategies for EV technologies. A major challenge with the electrification of transportation is the end of life of battery systems. A TEA is utilized to assess the economic viability of a novel Heterogeneous Unifying Battery (HUB) reconditioning system, which improves the performance of retired EV batteries before their 2nd life integration into grid energy storage systems (ESS). The modeling work incorporates the costs involved in the reconditioning process to determine the resale price of the batteries. Furthermore, the economic analysis is expanded to evaluate the use of HUB reconditioned batteries in a grid ESS, comparing it with an ESS assembled with new Lithium-ion (Li-ion) batteries. The minimum required revenue from each ESS is determined and compared with the estimated revenue of various grid applications to assess the market size. The findings reveal that the economical market capacity of these applications can fully meet the current supply of 2nd life EV batteries from early adopters in the United States (U.S.). However, as EV adoption expands beyond early adopters, the ESS market capacity may become saturated with the increased availability of 2nd life batteries. Despite the growing interest in EVs, their widespread adoption has been hindered, in part, by the lack of access to nearby charging infrastructure. This issue is particularly prevalent in Multi-Unit Dwellings (MUDs) where the installation of chargers can be unaffordable or unattainable for residents. To address this, TEA methodology is used to evaluate the levelized cost of charging (LCOC) for Battery Electric Vehicles (BEVs) at MUD charging hubs, aiming to identify economically viable charger deployment pathways. Specifically, multiple combinations of plug-in charger types and hub ownership models are investigated. Furthermore, the total cost of ownership (TCO) is assessed, encompassing vehicle depreciation, maintenance and repair, insurance, license and registration, and LCOC. The study also conducts a cradle to grave (C2G) LCA comparing an average passenger BEV and a gasoline conventional vehicle (CV) using geographical and temporal resolution for BEV charging. The TCO is coupled with the C2G GHG emissions to calculate the cost of GHG emissions reduction. The analysis demonstrates that MUD BEVs can reduce both costs and GHG emissions without subsidies, resulting in negative costs of GHG emissions reduction for most scenarios. However, charging at MUDs is shown to be more expensive compared to single-family homes, potentially leading to financial inequities. Additional research is required to assess the advantages of public charging systems and commercial EVs. While home charging is typically the primary option for EVs, public charging infrastructure is necessary for long-distance travel and urgent charging. This is especially important for commercial vehicles, which rely on public charging to support their operational requirements. Various charging systems have been proposed, including Direct Current Fast Charging (DCFC), Battery Swapping (BSS), and Dynamic Wireless Power Transfer (DWPT). This work includes a comparison of the TCO and global warming potential (GWP) of EVs of various sizes, specifically examining the charging systems utilized to determine precise location-specific sustainability outcomes. Nationwide infrastructure deployment simulations are conducted based on the forecasted geospatial and temporal demand for EV charging from 2031 to 2050. The TEA and LCA incorporate local fuel prices, electricity prices, electricity mixes, and traffic volumes. To account for the adaptability of variables that highly influence TCO and GWP, optimistic, baseline, and conservative scenarios are modeled for EV adoption, electricity mixes, capital costs, electricity prices, and fuel prices. The change to TCO by switching from ICEVs to EVs is shown to vary across scenarios, vehicle categories, and locations, with local parameters dramatically impacting results. Further, the EV GWP depends on local electricity mixes and infrastructure utilizations. This research highlights the dynamic nature of EV benefits and the potential for optimal outcomes through the deployment of multiple charging technologies. In conclusion, this research underscores the significance of strategically deploying EV charging infrastructure and utilizing retired EV batteries for grid energy storage. Instead of posing a challenge at end of life, these batteries are shown to be a solution for grid energy storage. The study also highlights the economic advantages of different charging infrastructure types for EVs and their role in driving EV adoption, resulting in potential GHG emissions reductions and consumer savings. Ultimately, widespread EV adoption and decarbonization of electrical grids are pivotal in achieving climate goals.
Open Access
Effects of fuel moisture content on pollutant emissions from a rocket-elbow cookstove
(Colorado State University. Libraries, 2018) van Zyl, Lizette, author; Volckens, John, advisor; Jathar, Shantanu, committee member; Anderson, Georgiana Brooke, committee member
Cookstoves have been studied in recent decades for their health- and environment-relevant emissions. Many pollutants, stoves, and burning parameters have been investigated across these studies, including fuel moisture content, which is believed to have substantial impact on stove emissions. Yet, the effects of fuel moisture content on emissions remain poorly characterized. To address this gap in knowledge, this study characterized particle and gas-phase pollutant emissions during a laboratory experiment exploring three levels of fuel moisture from a single tree sample. Moisture levels tested here varied from 5% to 30% water content, by weight. A novel technique for re-moisturizing the fuel samples was developed and employed to expedite the experimental duration and to ensure consistency across tests. Results from the study demonstrate strong trends in emissions related to changes in moisture content. Results also suggest there are benefits to drying wood to below 10% moisture content as compared to burning wood that is slightly above the 20% level recommended by the U.S. Environmental Protection Agency. When wood was dried to 5% instead of 25%, modified combustion efficiency improved and average mass-based emissions factors decreased for all pollutant species (formaldehyde, acetaldehyde, benzene, toluene, ethylbenzene, m+p-xylenes, o-xylenes, PM2.5, methane, carbon monoxide, and organic carbon) save black carbon. Dry fuel generated less smoke and higher temperatures than wet fuel. Wet fuel was also difficult to keep lit and burned much slower than dry fuel. Efficiency, burn rate, and stove temperature all affect the way people use their stoves for heating or cooking. Since moisture content impacted efficiency, burn rate, and temperature during this study, as well as multiple gas and particle-phase pollutants, moisture content should be accounted for in future stoves studies, both in the lab and in the field.
Open Access
Effects of near-source coagulation of biomass burning aerosols on global predictions of aerosol size distributions and implications for aerosol radiative effects
(Colorado State University. Libraries, 2018) Ramnarine, Emily, author; Pierce, Jeffrey, advisor; Kreidenweis, Sonia, committee member; Jathar, Shantanu, committee member
Biomass burning is a significant global source of aerosol number and mass. In fresh biomass burning plumes, aerosol coagulation reduces aerosol number and increases the median size of aerosol size distributions, impacting aerosol radiative effects. Near-source biomass burning aerosol coagulation occurs at spatial scales much smaller than the grid boxes of global and many regional models. To date, these models ignore sub-grid coagulation and instantly mix fresh biomass burning emissions into coarse grid boxes. A previous study found that the rate of particle growth by coagulation within an individual smoke plume can be approximated using the aerosol mass emissions rate, initial size distribution median diameter and modal width, plume mixing depth, and wind speed. In this thesis, we use this parameterization of sub-grid coagulation in the GEOS-Chem-TOMAS global aerosol microphysics model to quantify the impacts on global aerosol size distributions, the direct radiative effect, and the cloud-albedo aerosol indirect effect. We find that inclusion of biomass burning sub-grid coagulation reduces the biomass burning impact on the number concentration of particles larger than 80 nm (a proxy for CCN-sized particles) by 37% globally. This CCN reduction causes our estimated global biomass burning cloud-albedo aerosol indirect effect to decrease from -76 to -43 mW m−2. Further, as sub-grid coagulation moves mass to sizes with more efficient scattering, including it increases our estimated biomass burning all-sky direct effect from -224 to -231 mW m−2 with assumed external mixing and from -188 to -197 mW m−2 with assumed internal mixing with core-shell morphology. However, due to differences in fire and meteorological conditions across regions, the impact of sub-grid coagulation is not globally uniform. We also test the sensitivity of the impact of sub-grid coagulation to two different biomass burning emission inventories, to various assumptions about the fresh biomass burning aerosol size distribution, and to two different timescales of sub-grid coagulation. The impacts of sub-grid coagulation are qualitatively the same regardless of these assumptions.
Open Access
Engineering phthalocyanines and carbon composites for use in sensing, microfluidics and dye sensitized solar cells
(Colorado State University. Libraries, 2018) Klunder, Kevin Jay, author; Henry, Charles, advisor; Prieto, Amy, committee member; Reynolds, Melissa, committee member; Barisas, George, committee member; Jathar, Shantanu, committee member
The focus of this thesis is on fundamental and applied electrochemistry in the areas of photovoltaics, sensors, and microfluidics. Photovoltaics are important as they are needed to reduce the amount of greenhouse gases, pollution, and reliance on finite energy sources that are currently associated with energy production. A thin film photovoltaic device known as a dye sensitized solar cell (DSSC) is studied in his work. Specifically the cathode of the DSSC is studied in detail. A new method to create a highly transparent and catalytic DSSC cathode coating is proposed. The phthalocyanine based coatings have ~97% transmittance at 550 nm and low charge transfer resistance of ~1.3 Ω cm2, representing one of the best cathode coatings in terms of transparency and charge transfer resistance to date. Electrochemical sensors and electrochemical microfluidics can be used to monitor air, water and soil pollution, both of which can occur from anthropogenic and/or natural sources. Quantifying this pollution is vital for human and animal safety. Electrochemical sensors are also used for health diagnostics and are commonly applied in blood glucose monitoring. It is projected that wearable forms of electrochemical sensors will emerge as a vital class of real-time point-of-care sensors to monitor health indicators in the near future. To advance the field of electrochemical sensors and electrochemical microfluidics low cost, easily miniaturized, patterned, and shaped electrodes are needed. The work here introduces a new fabrication method for carbon composites which enables electrodes to be patterned and made into micron features in a facile manor through solvent or melt processing. The composites are also shown to be easily integrated into microfluidic devices, demonstrated with the assembly of electrochemical droplet microfluidics. The ease of fabrication of the new composites represents a milestone for the widespread use of low cost carbon composites in complex electrochemical systems. Within this thesis, Raman, SEM, XRF, and a wide range of electrochemical redox species and techniques are used to determine what factors affect the electrochemical activity, capacitance, and conductivity of the carbon composites. Finally, phthalocyanines for uses in electrochemical catalysis are a recurring theme throughout the thesis. Chapter 4 is dedicated to creating new types of electropolymerizable phthalocyanines. Cobalt phthalocyanine is integrated into the carbon composites from Chapter 2 for uses in thiol oxidation and the sensing of thiols. The thiol of interest was dithiothreitol (DTT) which is used in the "DTT assay". The DTT assay is a chemical measure of oxidative potential of particulate matter, and is commonly used to try and understand health effects relating to air pollution. Here, low volume disposable cells, as well as flow based sensors are developed for the detection of DTT.
Open Access
Evaluation of commercially available on-line analyzers for measurement of natural gas contaminants
(Colorado State University. Libraries, 2021) Zineddin, Khalid Mohamad, author; Olsen, Daniel, advisor; Jathar, Shantanu, committee member; Carlson, Kenneth, committee member
The proliferation of natural gas usage and extraction has led to never-before-seen levels of demand across the United States in several industries. Because of this increased demand for quality processed natural gas, a need has arisen to streamline its processing and distribution for faster and more efficient delivery to customers. One method to achieve this is by consolidating natural gas contaminant analyzers at processing and distribution sites; current sites typically operate with multiple separate gas analyzers, each dedicated to measuring one individual contaminant species. Recent developments in laser-based gas composition analysis (in particular Tunable Diode Laser Absorption Spectroscopy or TDLAS) as well as advances in gas chromatograph (GC) technology have given rise to commercially-available analyzing instruments which are capable of detecting and measuring multiple gas contaminants simultaneously. In order to verify the effectiveness and reliability of these new technologies, three specific gas analyzing instruments (herein referred to as Instruments A, B, and C) were selected for in-depth laboratory and field testing. The main objective of this research is to quantify the accuracy, precision and uncertainty of these new multi-species gas analyzers and compare their performance with existing gas analyzers currently in use by natural gas processing and distribution organizations. Four natural gas contaminant species were specified for evaluation of the natural gas contaminant analyzers; these are water (H2O), hydrogen sulfide (H2S), oxygen (O2) and carbon dioxide (CO2). Laboratory testing was performed first by sampling existing natural gas from three separate sources then by custom gas mixtures blended in-house from pure component gases to simulate four levels of contaminants (Low, two Mid-range blends, and High). For results verification a sample of each gas mixture (both source natural gas and custom blends) was submitted to EMPACT Analytical Inc. for composition analysis. Following laboratory testing, two instruments were selected for ongoing (through February 2022) field testing to simulate "real-world" conditions and their results are compared with those of existing on-site gas contaminant analyzers. It was concluded that Instrument A (TDLAS-based) was the most accurate and reliable of the three analyzers under test and required the least amount of user intervention to maintain satisfactory operation. Instrument B (also TDLAS-based) ranked a close second-place, having slightly less accuracy than Instrument A in measuring gas concentrations and falling short by its inability to detect O2; it also experienced multiple failures which required user intervention and/or shipping the instrument back to the manufacturer for repair and reconfiguration. Instrument C (GC-based) performed the poorest of the three analyzers with very low accuracy in measuring O2 and H2O to the point of being essentially non-detected species; it also required in-depth user intervention for initial setup and on multiple occasions during operation which was determined to be inappropriate for the intended application.
Open Access
Experimental investigation of automotive refueling system flow and emissions dynamics to support CFD development
(Colorado State University. Libraries, 2019) Stoker, T. McKay, author; Windom, Bret C., advisor; Jathar, Shantanu, committee member; Carter, Ellison, committee member
Government regulations restrict the evaporative emissions during refueling to 0.20 grams per gallon of dispensed fuel. This requires virtually all of the vapors generated and displaced while refueling to be stored onboard the vehicle. The refueling phenomenon of spit-back and early click-off are also important considerations in designing refueling systems. Spit-back is fuel bursting past the nozzle and into the environment and early click-off is the pump shutoff mechanism being triggered before the tank is full. Both are detrimental to customer satisfaction, and spit-back leads to failing government regulations. Development of a new refueling system design is required for each vehicle as packaging requirements change. Each new design (or redesign) must be prototyped and tested to ensure government regulations and customer satisfaction criteria are satisfied. Often designs need multiple iterations, costing money and time in prototype-based validation procedures. To conserve resources, it is desired to create a Computational Fluid Dynamics (CFD) tool to assist in design validation. To aid in creating such a model, controlled experiments were performed to inform and validate simulations. The simulations and experiments were performed on the same in-production refueling system. Test data provided characterization of non-trivial boundary conditions. Refueling experiments gave points of comparison for CFD results, especially the tank pressure. Finally, collection of emissions data during refueling experiments provided insight into the travel of gasoline vapor in the refueling system. All the information gathered provides greater understanding of the refueling process and will aid the continued development of CFD models for refueling.
Open Access
Filtration efficiency and breathability of fabric masks and their dependence on fabric characteristics
(Colorado State University. Libraries, 2022) Fontenot, Jacob, author; Volckens, John, advisor; Carter, Ellison, committee member; Jathar, Shantanu, committee member
Throughout the COVID-19 pandemic, the demand for face coverings offering two-way protection significantly increased, which resulted in widespread use of masks made from common fabrics (e.g., wool, cotton, and synthetic materials). However, the effectiveness of these fabric masks, which vary in material and design, is not well understood. This work investigates the performance of fabric masks, namely filtration efficiency and breathability, and their dependence on fabric characteristics. Filtration efficiency (FE) and flow resistance – a measure of mask breathability – were evaluated for 50 fabric masks, followed by individual layer testing (n = 70 total layers). The characteristics of the fabric layers, namely yarn diameter, fiber diameter, thread count, air permeability, porosity, cloth cover factor, infra-red (IR) attenuation, and fabric thickness were quantified in a laboratory setting. Fabric mask FEs were relatively low (i.e., < 50%) for submicron particles but increased with particle diameter. Approximately half of the masks achieved a FE meeting the Level 1 barrier standard specified in ASTM F3502-21. The FE and flow resistance of the component fabric layers was found to accurately predict the FE and flow resistance of the entire mask; therefore, we find that fabric masks can generally be treated as filters in series. FE exhibited the strongest relationship with cloth cover factor, IR attenuation, air permeability, and the number of fabric layers; in contrast, we found little to no relationship between FE and yarn diameter, fiber diameter, thread count, porosity, fabric thickness, and fabric material (e.g., natural vs. synthetic). Results of this work should help inform the design of more effective fabric masks, which could prove especially useful for airborne infectious disease response efforts in resource limited environments (i.e., where N95 technologies are not available) around the planet.
Open Access
Horizontal and vertical forest complexity interact to influence potential fire behavior
(Colorado State University. Libraries, 2022) Ritter, Scott Michael, author; Hoffman, Chad, advisor; Battaglia, Michael, committee member; Mell, William, committee member; Ex, Seth, committee member; Jathar, Shantanu, committee member
Wildland fire behavior is a dynamic process controlled by complex interactions among fuels, weather, and topography. There is significant need to better understand the role of fuels and, particularly, complex arrangements of fuels, on potential fire behavior and effects as a there is a growing emphasis on forest treatments that emulate the heterogenous structures of historical forest ecosystems. Ideally such treatments are intended to reduce fire hazard while concurrently improving resilience to a wide range of disturbance agents and restoring the natural ecosystem dynamics that maintained these forest structures. One way to evaluate how the complex forest structures created by these treatments will influence fire behavior are modeling approaches that account for dynamic interactions between fire, fuels, and wind. These physical fire models build from computational fluid dynamics methods to include processes of heat transfer, vegetative fuel dehydration and pyrolysis, and gas phase ignition and combustion. In this work, several aspects of horizontal and vertical forest structure were evaluated to understand how spatial complexity influences fire behavior, with a particular emphasis on the transition of a surface fire into tree crowns. I used a combination of spatially explicit field data and a physics-based wildfire model, the Wildland-Urban Interface Fire Dynamics Simulator (WFDS), to deepen our fundamental understanding of fire behavior, inform the design of forest treatments that aim to achieve a variety of ecological and social objectives, and develop hypotheses related to the pattern-process feedbacks that contributed to the maintenance of resilient forests across millennia. Chapter 2 presents a simulation study focused on the relationship between horizontal forest structure and surface to crown heat transfer and crown fire initiation. The results indicated that relative to larger 7- and 19-tree groups, isolated individual trees and 3-tree groups had greater convective cooling and reduced canopy heat flux. Because isolated individuals and 3-tree groups were exposed to less thermal energy, they required a greater surface fireline intensity to initiate torching and had less crown consumption than trees within larger groups. Similarly, I found that increased crown separation distance between trees reduced the net heat flux leading to reduced ignition potential. These findings identify the potential physical mechanisms responsible for supporting the complex forest structures typical of high-frequency fire regimes and may be useful for managers designing fuel hazard reduction and ecological restoration treatments. Chapter 3 extends chapter 2 by investigating how different levels and types of vertical heterogeneity influence crown fire transition and canopy consumption within tree groups. These results show the importance of fuel stratum gap (or canopy base height) on vertical fire propagation, however vertical fire propagation was mediated by the level of horizontal connectivity in the upper crown layers. This suggests that the fuel stratum gap cannot fully characterize the torching hazard. The results also indicate that as the surface fire line intensity increases, the influence of horizontal connectivity on canopy consumption is amplified. At the scale of individual tree groups, the perceived hazard of small, understory trees and vertical fuel continuity may be offset by lower horizontal continuity (or canopy bulk density) within the midstory and overstory crown layers. Chapter 4 compares outcomes from four real-world forest treatments that cover a range of potential treatment approaches to evaluate their impacts of forest spatial pattern and potential fire behavior. My results indicate that restoration treatments created greater vertical and horizontal structural complexity than the fuel hazard reduction treatments but resulted in similar reductions to potential fire severity. However, the restoration treatments did increase the surface fire rate of spread which suggests some potential fire behavior tradeoffs among treatment approaches. Overall, these results suggest the utility of restoration treatments in achieving a wide range of management objectives, including fire hazard reduction, and that they can be used in concert with traditional fuel hazard reduction treatments to reduce landscape scale fire risk. Together this work shows that tree spatial pattern can significantly influence crown fire initiation and canopy consumption through alterations to net heat transfer and feedbacks among closely spaced trees. At the scale of the tree group these results suggest that larger tree groups may sustain higher levels of canopy consumption and mortality as they are easier to ignite and, in cases with small separation between crowns, can sustain horizontal spread resulting in density-depended crown damage. These findings carry over to vertically complex groups where the spatial relationship between small, understory trees and larger, overstory trees has a large impact on the ability of fire to be carried vertically. Further, in these vertically complex groups reducing the density (and/or increasing the horizontal separation) of the overstory trees, resulted in lower rates of crown fuel consumption, therefore, mitigating some of the "laddering" effect caused by the presence of small understory trees. These complex interactions between vertical and horizontal aspects of stand structure were born out in my evaluation of the measured forest treatments, where similar crown fire behavior reductions were observed across various stand structures. Overall, this work shows that forest managers can apply treatments to achieve a wide range of ecological benefits while simultaneously increasing fire resistance and resilience.
Open Access
Inorganic gas-aerosol partitioning in and around animal feeding operation plumes in northeastern Colorado in late summer 2021
(Colorado State University. Libraries, 2023) Li, En, author; Pierce, Jeffrey, advisor; Fischer, Emily, advisor; Jathar, Shantanu, committee member; Sullivan, Amy, committee member
Ammonia (NH3) from animal feeding operations (AFOs) is an important source of reactive nitrogen in the US, but despite its ramifications for air quality and ecosystem health, its near-source evolution remains understudied. To this end, Phase I of the Transport and Transformation of Ammonia (TRANS2Am) field campaign was conducted in the northeastern Colorado Front Range in summer 2021 and characterized atmospheric composition downwind of AFOs during 10 research flights. Airborne measurements of NH3, nitric acid (HNO3), and a suite of water-soluble aerosol species collected onboard the University of Wyoming King Air (UWKA) research aircraft present a unique opportunity to investigate the sensitivity of particulate matter (PM) formation to AFO emissions. We couple the observations with thermodynamic modeling to predict the seasonality of ammonium nitrate (NH4NO3) formation. We find that during TRANS2Am northeastern Colorado is consistently in the NH3-rich and HNO3-limited NH4NO3 formation regime. Further investigation using the Extended Aerosol Inorganics Model (E-AIM) reveals that summertime temperatures (mean: 23 ˚C) of northeastern Colorado, especially near the surface, inhibit NH4NO3 formation despite high NH3 concentrations (max: ≤ 114 ppbv). Lastly, we model and winter conditions to explore the seasonality of NH4NO3 formation and find that cooler temperatures could support substantially more NH4NO3 formation. Whereas summertime NH4NO3 only exceeds 1 µg m-3 ~10% of the time in summer, modeled NH4NO3 would exceed 1 µg m-3 61% (88%) of the time in spring/autumn (winter), with a 10°C (20°C) temperature decrease relative to the campaign.