AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
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Molecular Chemistry of Brown Carbon (BrC) in Biomass Burning Aerosols
PENG LIN, Julia Laskin, Sergey Nizkorodov, Alexander Laskin, Nir Bluvshtein, Yinon Rudich, Pacific Northwest National Laboratory
Abstract Number: 408 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Atmospheric brown carbon (BrC), which represents a poorly-defined collection of particulate organic compounds that efficiently absorb solar radiation in the ultraviolet (UV) and visible (Vis) region, is ubiquitously found in the global troposphere. Biomass burning (BB), in forms of wildfire and prescribed fire, is suggested to be a significant source of BrC in the atmosphere. In this study, the molecular level chemical composition of BrC from BB smoke particles and BB influenced atmospheric aerosols was investigated with a HPLC/PDA/HRMS platform. In contrast to the extremely compositional complexity and diversity of BrC freshly emitted from BB, the chemical composition of BrC in atmospherically aged BB aerosols was relatively simple, where majority of the light absorption can be explained by nitro-phenolic compounds and their derivatives. The results indicate that atmospheric aging processes play important roles in regulating the light absorption properties and chemical characteristics of BrC emitted from BB. The chemistry of BrC during the aging processes was revealed through a series laboratory controlled aging experiments on BB smoke particles and mimic standard compounds.