Aerosol formation and heterogeneous chemistry in the atmosphere

A. Monod and Y. Liu

Aix-Marseille Univ., Laboratoire Chimie Provence, 13331 Marseille Cedex 03, France
CNRS, Laboratoire Chimie Provence, 13331 Marseille Cedex 03, France

Published online: 27 January 2012

Abstract

A general presentation of the Earth’s atmosphere is provided, with the associated photochemical processes and oxidizing capacity. The article focuses on the atmospheric reactivity of Volatile Organic Compounds (VOCs) and the associated reaction products in the gas phase (ozone, oxygenated organic compounds, organic nitrates …) and in the particle phase, namely, the Secondary Organic Aerosols (SOA). The understanding of the processes leading to SOA formation is currently a “hot topic” because of: i) their high concentrations in the measured total organic matter, and ii) their potential important impacts on health and climate change. The initial theory of SOA formation was based on thermodynamic phase transfers of oxidized reaction products of VOCs, but it failed to explain the presence of high molecular weight (high-MW) compounds observed in SOA as well as a 1 to 2 orders of magnitude discrepancy between models and observations on the quantity of SOA. Therefore, different research investigations have been proposed such as heterogeneous and aqueous phase reactivity of organic compounds.