Grantee Research Project Results
2024 Progress Report: Mapping Urban Emissions of Sub-10 nm Particles using a Mobile Platform
EPA Grant Number: R840427Title: Mapping Urban Emissions of Sub-10 nm Particles using a Mobile Platform
Investigators: Petters, Markus , Meskhidze, Nicholas
Institution: University of California Riverside , North Carolina State University at Raleigh
EPA Project Officer: Chung, Serena
Project Period: May 1, 2022 through April 30, 2025 (Extended to April 30, 2026)
Project Period Covered by this Report: May 1, 2024 through April 30,2025
Project Amount: $730,525
RFA: Measurement and Monitoring Methods for Air Toxics and Contaminants of Emerging Concern in the Atmosphere (2021) RFA Text | Recipients Lists
Research Category: Watersheds , Endocrine Disruptors , Environmental Engineering , Air Quality and Air Toxics
Objective:
The objectives of this project are to (1) design and build a platform to measure the size, morphology, and elemental composition of sub-10 nm particle emissions and (2) to demonstrate that the platform can be used for source identification and apportionment studies and creation of the detailed maps with emission inventories for sub-10 nm particles in urban environments.
Progress Summary:
We have shown that biosolid processing facilities can emit high concentrations of nanoparticles. Repeated and persistent episodes of elevated particle number concentrations were observed downwind from a facility, with concentrations up to 1,000,000 cm-3, for particles between 5 and 20 nm in mobility diameter. Particle numbers generally correlated with CO2 emissions. Particles were composed primarily of carbon, with some sulfur, nitrogen, and phosphorus. Agglomerated morphology observed under the electron microscope suggests either solid or highly viscous phase states. The observed elevated number concentrations align with particle generation via gas-phase nucleation, likely triggered by high volatile organic compounds emissions from the facility.
Using ambient aerosol measurements from the Jordan Hall rooftop at North Carolina State University combined with EPA's AERMOD Gaussian plume model, researchers demonstrated that elevated sub-10 nm particle number concentrations exceeding 373,000 cm⁻³ were attributable to three campus utility plants: Cates Avenue Steam Plant, Yarbrough Central Utility Plant, and Centennial Campus Central Utility Plant. The modeling study incorporated individual point sources with emission factors of 5 × 10⁻⁴ g s⁻¹ and key meteorological parameters including wind patterns, solar radiation, and planetary boundary layer height to predict nanoparticle concentrations at various elevations (0-20 meters) around Jordan Hall. The AERMOD model successfully captured the inverse relationship between particle number concentrations and boundary layer height, accurately predicting elevated nanoparticle events during periods of shallow atmospheric mixing, while wind pattern analysis enabled differentiation of distinct emission plumes from individual power plants reaching the measurement site.
Future Activities:
Future activities will focus on sub-10 nm emissions from aircraft in the approach path of Ontario international airport (ONT). A second focus will be composting facilities in the Southern California area. A third activity will be continuing geospatial mapping surveys to identify sub-10 nm emission sources. The final activity will be the evaluation of diesel nano-additives on nanoparticle emissions, following up on observed nanoparticle emissions from certain diesel vehicles observed during a city wide survey of the Raleigh metropolitan area.
Journal Articles:
No journal articles submitted with this report: View all 4 publications for this projectSupplemental Keywords:
ambient air, atmosphere, exposure, toxics, surveys, measurement methods, North Carolina (NC), South Coast Air Quality Management DistrictRelevant Websites:
N/A
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.