Advances in Research on the Sources, Distribution, and Isotopic Tracing of Low Molecular Weight Monocarboxylic Acids in the Atmosphere

Abstract

Low molecular weight (C1−C10) monocarboxylic acids constitute one of the most abundant classes of atmospheric organic compounds. They occur ubiquitously in the gas, particle, and aqueous phases and exert significant influences on atmospheric acidity, radiative forcing, and the global carbon and water cycles. Stimulated by the severe acid rain crisis in the 1980s, research on the geochemical processes of atmospheric monocarboxylic acids advanced rapidly but declined over the past two decades following the effective control of acid rain. However, in recent years, the global implementation of emission reduction policies has substantially altered aerosol composition and properties, potentially leading to changes in the gas-particle partitioning behaviour and environmental fate of monocarboxylic acids. This paper provides a comprehensive review of the sampling and analytical techniques, sources and sinks, and global distribution patterns of monocarboxylic acids in the atmosphere and precipitation, and further discusses the application prospects of dual-carbon isotope (δ13C-Δ14C) techniques. By integrating these aspects, this study aims to provide a theoretical foundation for revitalizing and deepening research on the geochemical processes of atmospheric monocarboxylic acids.