Grantee Research Project Results

2024 Progress Report: Scalable chemical mechanisms of emerging sources for community air quality predictions

EPA Grant Number: R840007
Title: Scalable chemical mechanisms of emerging sources for community air quality predictions
Investigators: Barsanti, Kelley , Emmons, Louisa , Carter, William , Orlando, John
Institution: University of California - Riverside , National Center for Atmospheric Research
EPA Project Officer: Chung, Serena
Project Period: August 1, 2020 through July 31, 2023 (Extended to January 31, 2026)
Project Period Covered by this Report: August 1, 2023 through July 31,2024
Project Amount: $784,743
RFA: Chemical Mechanisms to Address New Challenges in Air Quality Modeling (2019) RFA Text | Recipients Lists
Research Category: Watersheds , Endocrine Disruptors , Environmental Engineering , Air Quality and Air Toxics , Air

Objective:

The objectives of this project are to: 1) derive and evaluate explicit chemical mechanisms for representative individual compounds identified in emerging sources using well-established and peer-reviewed protocols; 2) develop approaches to reduce explicit chemical mechanisms, scalable to specific applications; and 3) apply and evaluate new chemistries and reduced chemical mechanisms in air quality model simulations. The goal and the objectives have not changed from the application.

Progress Summary:

Most of the activity in this reporting period has been focused on Obj. 2, developing approaches for mechanism reduction, scalable to specific applications. Specifically, time has been spent developing model structure that allows interchangeability of different mechanisms (e.g., generated using the SAPRC mechanism generation system (MechGen) or the Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A)), different box models (e.g., GECKO-A or SSH-Aerosol), and different reduction targets (e.g.., OH reactivity or secondary organic aerosol (SOA) mass). The latter is particularly important for mechanism scaling, as this is dependent on the target application. Significant accomplishments made during this fourth year were: 1) the first complete documentation of the chemical basis of SAPRC MechGen was accepted for publication; 2) documentation of the SAPRC MechGen software system was completed, and user manuals and a GitHub page were developed to facilitate wider usage, version control, and community contributions; 3) Zhizhao Wang and Julia Lee Taylor worked with collaborators to develop and test reduced GECKO-A mechanisms generated using the Automated Model Reduction (AMORE) algorithm; and 4) Zhizhao Wang developed and tested a third version of the GENerator of reduced Organic Aerosol mechanism (GENOA), with improved flexibility in regard to mechanism reduction parameters and model testing parameters. There are a growing number of collaborations using GECKO-A and MechGen generated mechanisms that is also contributing to the project objectives and outcomes, particularly mechanism evaluation with laboratory data and reduced mechanism performance evaluation.

Future Activities:

The activities in year five will focus on manuscript submissions to complete Obj. 2, and tasks to complete Obj. 3. We will be developing and evaluating reduced mechanisms (single and multiple precursor) describing specific sources and/or ambient conditions and used different reduction criteria. We will be developing a library of mechanism for community use, and will more generally continue to grow and support GECKO-A and MechGen user communities.

Journal Articles on this Report : 1 Displayed | Download in RIS Format

Publications Views
Other project views:	All 7 publications	3 publications in selected types	All 3 journal articles

Publications
Type	Citation	Project	Document Sources
Journal Article	Carter WPL, Jiang J, Orlando JJ, Barsanti KC. Derivation of atmospheric reaction mechanisms for volatile organic compounds by the SAPRC mechanism generation system (MechGen). Atmospheric Chemistry and Physics. 2025;25(1):199-242	R840007 (2024)	Full-text: Copernicus - Full text HTML Exit

Supplemental Keywords:

GECKO, SAPRC, peroxy radicals, chemical mechanisms. organics, environmental data

Relevant Websites:

GECKO-A Exit

SAPRC Mechanism Generation System (MechGen) GitHub page Exit

Progress and Final Reports:

Original Abstract

The 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.