SARP East 2025 Atmospheric Chemistry Group

Educational advisor:

Stacey Hughes, University of New Hampshire

Graduate mentor:

Katherine Paredero, Georgia Institute of Technology

Kaylena Pham, University of Southern California

Wetlands represent a dominant natural source of methane emissions to the atmosphere through methanogenesis, a process that produces methane in nutrient-depleted anoxic sediments, or through decomposition. In coastal wetlands, particularly in brackish regimes such as the Alligator River, severe storms and sea level rise intensify inland saltwater intrusion. This leads to massive destruction of vegetation and the formation of ghost forests, large areas of dead vegetation. Widespread forest loss caused by salinization suggests elevated methane emissions in areas under plant stress due to increased rates of decomposition from plant death. Previous research has not yet considered ghost forests when estimating wetland methane emissions, which led us to explore emission concentrations in two wetlands with similar plant compositions: the Great Dismal Swamp and the Alligator River.

In this work, we used in situ measurements collected aboard the Dynamic Aviation B-200 aircraft during the NASA Student Airborne Research Program (SARP) 2025 flight campaign. Methane and carbon monoxide measurements were determined using a PICARRO gas concentration analyzer. These data were then linked to Normalized Difference Vegetation Index (NDVI) images from the Terra satellite’s Moderate Resolution Imaging Spectroradiometer (MODIS) instrument. With these two datasets, we investigated how vegetation stress influences methane emissions. We observed greater vegetation stress in the Alligator River than in the Great Dismal Swamp. Additionally, the Alligator River has greater methane concentration variability in areas with greater vegetation stress. In contrast, methane measurements above the Great Dismal Swamp have narrower distributions and less stress on vegetation. This comparison of wetlands in different vegetative states suggests a potential link between ecosystem stress and elevated methane emissions in wet environments. Interestingly, despite these differences, the Great Dismal Swamp had a slightly higher average methane concentration (2.11 ppm) than the Alligator River (1.96 ppm). Our results highlight the importance of improving our understanding of the types of vegetation conditions that lead to increased methane on wetland regimes.

Carson Turner, University of North Dakota

Methane is one of the most potent greenhouse gases in the atmosphere, with a warming potential approximately 28 times that of carbon monoxide. When looking at the global methane budget, wetlands are the largest natural source of methane, accounting for 20-40% of global methane emissions. Methane emissions from wetlands have been shown to have the greatest uncertainty due to both a lack of in situ measurements to compare with models and a lack of understanding of how different conditions, such as soil moisture and air temperature, affect methane emissions. This study focuses specifically on the Great Dismal Swamp (GDS), located on the border of southeastern Virginia and northeastern North Carolina, to investigate emissions over the region using data collected from flights conducted as part of the Student Airborne Research Program (SARP) in the summer of 2025. A PICARRO gas concentration analyzer was used to collect high-frequency measurements of methane and carbon monoxide. The two research flights followed similar flight paths around the GDS on June 23 and 24. The methane flux was then calculated using the mass balance approach for each flight. The methane flux values ​​were measured at 0.037 kg/s and 0.603 kg/s for 23 and 24 respectively. A similar study of wetlands in northern Sweden and Finland found an average methane flux value of 5.56 kg/s. A decrease in the methane flux value was observed on the day of flight associated with higher temperatures, which contradicts previous research on the relationship between methane emissions and temperature. Future work includes using these flux measurements to improve our understanding of wetland methane emissions in models and further explore the relationship between methane emissions and soil moisture.

Alek Libby, Florida State University

Urban ozone pollution remains a significant air quality problem in many U.S. cities. Tropospheric ozone is not emitted directly but is formed by photochemical reactions involving volatile organic compounds (VOCs) and nitrogen oxides (NOₓ) in the presence of sunlight, particularly during summer when incoming solar radiation is increased. The EPA’s national ambient air quality standard for ground-level ozone is 70 ppb, measured as an 8-hour average. Although exceedances of this standard have declined nationally, it remains critical to understand how the composition of emissions varies across metropolitan areas. This study examines the dynamics of VOC composition and ozone formation in three mid-Atlantic urban environments: Baltimore, Richmond, and Norfolk. In situ whole air samples (WAS) were collected aboard the Aviation Dynamics B200 aircraft during NASA’s Student Airborne Research Program (SARP) 2024 campaign. Gas chromatography was used to quantify the VOC composition of each sample. Additional airborne data from the CAFE and CANOE instruments provided measurements of formaldehyde (HCHO) and nitrogen dioxide (NO₂), respectively. This study examined measurements collected below the boundary layer and in urban ring roads to assess the regional ozone production potential. Results showed that Baltimore had significantly lower levels of key anthropogenic VOCs, particularly n-butane, i-pentane, and n-pentane. VOC/NOₓ ratios place Richmond and Norfolk in NOₓ-limited regimes, while Baltimore is in the transition zone, supported by HCHO/NO₂ ratios averaging 2.44 in Baltimore compared to 5.14 and 5.09 in Norfolk and Richmond. Baltimore continues to experience significantly more ozone exceedance days than Norfolk and Richmond, which is likely linked to high NO₂ levels in the region. Although reducing VOCs can help, these results suggest that NOₓ reductions are likely more effective in mitigating ozone in the Baltimore region. Future work could replicate this analysis using the SARP 2025 dataset, which was collected on warm, stagnant days favorable for ozone production.

Hannah Suh, University of California, Santa Cruz

Volatile organic compounds (VOCs) play a key role in tropospheric photochemistry because they react with nitrogen oxides (NOx) exposed to sunlight to produce tropospheric ozone (O3). VOCs and tropospheric O3 can have negative effects on air quality and human health. Understanding the sources of VOCs in urban areas such as Baltimore is critical to informing future air quality policies. In this study, in situ VOC measurements collected aboard the Aviation Dynamics B200 aircraft during NASA’s Student Airborne Research Program (SARP) were analyzed to characterize potential emission sources in the Baltimore area. VOC datasets from two June 24 flights that flew over this location were studied. This flight data was collected using aircraft instruments on the Aviation Dynamics B200, primarily the Whole Air Sampler (WAS). The WAS cartridges were then processed in the laboratory using gas chromatography, which identified the different mixing ratios of VOCs in the air. VOC ratios along with positive matrix factorization (PMF), which reduces an entered data matrix to separate potential contributions from emission sources, were compared to each other to account for the most notable VOC sources in the Baltimore region. A total of six sources were examined via the PMF for this region. The three main sources appear to be oil and natural gas emissions, biogenic emissions and vehicles. Chemical signature ratios indicate the presence of mixed plumes of industrial and urban emissions, with many significant correlations with ethyne. These results indicate that the oil and gas industries, biogenic sources, and urban sources such as vehicles are the primary contributors to VOC signature ratios in the Baltimore region. A logical next step for this research would be to compare VOC signature ratios across multiple years to assess temporal trends.

Aashi Parikh, Boston University

Hopewell, Virginia, is home to a cluster of major chemical facilities, whose emissions have sparked concerns in nearby communities about air pollution and health disparities. Although there is information on historical pollution at Hopewell, few studies provide comprehensive analysis of volatile organic compounds (VOCs). This study examines the distribution of VOCs in the Hopewell Industrial Corridor and

In situ whole air samples (WAS) were collected aboard the Aviation Dynamics B200 during the NASA Student Airborne Research Program in June 2024. In this study, samples collected at Hopewell were compared to the rest of the flight. The values ​​were separated by chemical families and improvements were identified. The analysis showed Hopewell had significant levels of aromatics, with 60 ppt benzene, 119 ppt toluene and 47 ppt styrene, which are VOCs linked to respiratory illnesses, neurological disorders, reproductive problems and cancer. Aromatics observed over Hopewell were approximately 5 times greater than those over the remaining flight path. According to the EPA, these carcinogenic compounds do not have a safe threshold for chronic exposure. Thus, long-term exposure to these compounds may pose health risks. These findings reinforce existing disparities in health outcomes in the region, such as high cancer rates, and raise concerns about exposure to neighboring communities. Underserved communities are disproportionately affected by such health risks in Hopewell. Future research will assess VOC concentrations above Hopewell in 2025 and compare them to the 2024 baseline established in this study, which will help determine whether emissions reductions have occurred and whether regulatory or community interventions are showing an impact.