Atmospheric Chemistry of Biomass Burning Aerosol
EMSL Project ID
47874
Abstract
Biomass burning aerosols (BBA) are one of the most ubiquitous organic aerosol types with a source strength on the same order of magnitude as fossil fuel combustion. BBA have significant effects on air quality and climate on local, regional, and meso scales. During transport in the atmosphere, BBA particles undergo chemical transformations by reacting with highly reactive oxidants and radicals including O3, NO3, and OH. Although recognized as important, both the fundamental chemistry of BBA particles, due to their heterogeneous and multi-phase reactions, and their photochemistry, induced by the sun's irradiation, remain poorly understood. Here we propose a multi-institutional collaboration that combines experimental and multi-scale modeling expertise. It will yield a significantly improved understanding of fundamental particle chemistry which is crucial for assessing the impact of BBA particles on the environment, particularly air quality and climate. The chemical and physical particle transformation of BBA particles due to heterogeneous oxidation reactions will be investigated using authentic BBA particles collected during last year's Fire Lab at Missoula Experiment (FLAME)-4 field campaign. Particles deposited on various substrates will be subjected to chemical analysis by nano-DESI/HR-MS and chemical imaging analyses by CCSEM/EDX, TEM, Tof-SIMS, angle resolved XPS, micro-FTIR and STXM/NEXAFS, using equipment available at PNNL/EMSL and ALS/LBNL. At Stony Brook University, the particles will be exposed to atmospherically relevant concentrations of O3, NO3, and OH in presence of atmospheric relevant O2 concentrations, using flow reactor setups coupled to a chemical ionization mass spectrometer to allow control of reactant concentrations. A novel irradiated rectangular channel flow reactor will be employed to expose authentic BBA particles to O3 and OH under controlled visible and UV irradiation to stimulate photosensitized heterogeneous reactions. The uptake of water as a function of relative humidity (RH) will be determined using optical microscopy techniques. The proposed experiments will allow us to determine the chemical and morphological features of BBA particles and how they depend on biomass and burn conditions. The effect of atmospheric oxidants and radicals on the chemical and physical properties of particles will be determined. Applying highly specific single particle micro-spectroscopic tools, we will assess whether BBA mass increases or decreases due to these oxidation reaction, and whether these multiphase oxidation reactions lead to changes in chemical functionalities. The consequences of chemical aging on water uptake, and thus cloud forming potential, will be assessed. Kinetic flux modeling will yield physico-chemical parameters which will be utilized in atmospheric chemistry models to simulate particle transformation and to derive particle lifetimes.
The data provided by microscopic and micro-spectroscopic particle analyses will provide an extensive data set, which in combination with in-depth modeling studies of the underlying kinetic processes and their inclusion into atmospheric chemistry models, will allow assessment of the climatic impact of highly complex organic particles from biomass burning. Taking advantage of novel experimental and modeling approaches to study the chemistry of aerosols will address DOE BER's missions on the climatic and air quality impact of atmospheric aerosol and especially the EMSL science theme "Science of Interfacial Phenomena".
Project Details
Project type
Large-Scale EMSL Research
Start Date
2013-10-01
End Date
2015-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members
Related Publications
Knopf DA, PA Alpert, B Wang, RE O'Brien, ST Kelly, A Laskin, MK Gilles, and RC Moffet. 2014. "Micro-Spectroscopic Imaging and Characterization of Individually Identified Ice Nucleating Particles from a Case Field Study." Journal of Geophysical Research. D. (Atmospheres) 119:10,365-10,381. doi:10.1002/2014JD021866