Gas to particle distribution of low molecular weight dicarboxylic acids at two different sites in central Europe (Austria)

Abstract

Low molecular weight dicarboxylic acids exhibit a semivolatile behavior and partition between gas and aerosol phases in the atmosphere. Here we present an approach for sample collection, which provides information about the gas/particle distribution of the investigated acids, but with less effort compared to commonly used denuder systems. The procedure was applied for the investigation of C2–C9 dicarboxylic acids at a continental background site in central Europe (Mt. Rax) and the urban site Vienna. The averaged gas phase contribution ( n = 12 ) determined for individual low molecular weight dicarboxylic acids varied between 4% (malonic acid) and 37% (glutaric acid) of the total collected amounts. Using the observed gas/particle distributions effective Henry's law constants were estimated. Between the carbon chain length of the investigated dicarboxylic acids and the magnitude of K H * a dependence was observed — showing higher values for C2/C3 dicarboxylic acids (averaged 1.1 × 10 13 mol L - 1 atm - 1 ) and lower values for C4/C5 compounds (averaged 1.6 × 10 12 mol L - 1 atm - 1 ).