AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Reactivity of Water Soluble Organic Acids with Inorganic Particles Investigated by Micro-spectroscopy Analysis
BINGBING WANG, Steven Kelly, Rachel O'Brien, John Shilling, Alexei Tivanski, Ryan Moffet, Mary Gilles, Alexander Laskin, Pacific Northwest National Laboratory
Abstract Number: 338 Working Group: Aerosol Chemistry
Abstract Inorganic particles, such as sea salt and mineral dust, are main components in the atmosphere and undergo different aging processes which alter their physical and chemical properties. Depletion of chloride in sea salt particles was reported in previous field studies and was attributed to the acid displacement of chlorides with inorganic acids, such as nitric and sulfuric acids. Recently, we showed that NaCl can react with water soluble organic acids (WSOA) and release gaseous hydrochloric acid (HCl) resulting in formation of organic salts. A similar mechanism is also applicable to mixed WSOA/nitrate particles where multi-phase reactions are driven by the volatility of nitric acid. Furthermore, secondary organic material, which is a complex mixture of carboxylic acids, exhibits the same reactivity towards chlorides and nitrates. Here, we present a systematic study of reactions between atmospheric relevant WSOA/secondary organic materials and inorganic salts including NaCl, NaNO$_3, and Ca(NO$_3)$_2 using complementary micro-spectroscopy analysis including computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX), scanning transmission X-ray microscopy with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS), and micro-Fourier transform infrared spectroscopy (micro-FTIR).