2013 Progress Report: The role of nitrate radicals (NO3) in aerosol life cycle: Secondary organic aerosol formation and aging of atmospheric organic aerosols

EPA Grant Number: R835403
Title: The role of nitrate radicals (NO3) in aerosol life cycle: Secondary organic aerosol formation and aging of atmospheric organic aerosols
Investigators: Ng, Nga Lee
Institution: Georgia Institute of Technology
Current Institution: Georgia Institute of Technology
EPA Project Officer: Chung, Serena
Project Period: April 1, 2013 through March 31, 2016 (Extended to March 31, 2017)
Project Period Covered by this Report: April 1, 2013 through March 31,2014
Project Amount: $300,000
RFA: Anthropogenic Influences on Organic Aerosol Formation and Regional Climate Implications (2012) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Global Climate Change , Climate Change , Air

Objective:

The goal of this project is to experimentally determine the extent to which NO3 radicals (formed from anthropogenic NO2 and ozone) affect organic aerosol (OA) loading and composition over its atmospheric lifetime, taking into account secondary organic aerosol (SOA) formation from NO3 oxidation pathway and both daytime and night-time aging processes.

Progress Summary:

Work proceeded well during this year. We have performed extensive laboratory chamber experiments to investigate the effects of humidity and particle acidity on SOA formation from nitrate radical oxidation of biogenic volatile organic compounds (BVOCs). Experiments were performed with β-pinene under dry (< 5%) vs. humid (RH = 50%) conditions with ammonium sulfate vs. ammonium sulfate + sulfuric acid seeds. These experimental parameters were specifically designed to mimic the ambient reaction conditions in Centerville during the Southern Oxidant and Aerosol Study (SOAS). Notable results are:
  1. Determination of SOA yields from β-pinene+NO3 under dry and humid conditions.
  2. Identification of gas-phase oxidation products that are also detected in Centerville during SOAS.
  3. Determination of aerosol chemical composition: organonitrate formation.
  4. Assessment of organonitrate hydrolysis and its potential as a sink for atmospheric NOx.
  5. Investigation of aerosol aging via further oxidations by nitrate radicals.

Our results indicate that NO3 oxidation of BVOCs is an important source of SOA and can contribute substantially to night-time ambient SOA. These laboratory results can greatly aid the interpretation of ambient data obtained in the SAS study.

Future Activities:

There are three main goals for Year 2 of this project:
  1. Publication of SOA yields from β-pinene/NO3 under dry and humid conditions as well as the corresponding gas-phase and aerosol-phase chemical composition.
  2. Continued investigation of the effects of water and particle acidity on NO3 oxidation.
  3. Study the effect of photochemical aging on SOA formed from NO3 oxidation of selected biogenic compounds.

Journal Articles:

No journal articles submitted with this report: View all 40 publications for this project

Supplemental Keywords:

Partitioning, semivolatiles, multifunctional oxidation products

Relevant Websites:

School of Chemical & Biomolecular Engineering at Georgia Tech Exit

Progress and Final Reports:

Original Abstract
2014 Progress Report
2015 Progress Report
Final Report