Discovery of a Potent Source of Gaseous Amines in Urban China

Abstract

The strong atmospheric new particle formation in China’s highly polluted urban atmosphere can be potentially explained by the nucleation of sulfuric acid and amines, while it is unclear why urban atmospheres in China are enriched in amines. In urban China, human excreta are generally stored in septic tanks beneath buildings, which may release hazardous and odorous pollutants to the atmosphere through pipes on rooftops, i.e., ceiling ducts. Here for the first time, high-sensitive proton-transfer-reaction quadrupole-interface time-of-flight mass spectrometric measurements of gaseous amines emitted from the ceiling duct were performed in Shanghai. Driven by human activity, strong pulses of C2- and C3-amines emissions were persistently observed, in which a species (C3H7N) was rarely measured previously but emitted in significant quantities. Our direct source-determined emission ratios of amines to ammonia varied significantly with amine species and were systematically different from that previously assumed in models. These observations, if generalized, would call for a substantial change of urban amine emissions and modelling. A gridded amine emission inventory from the septic system was developed based on city-wide ammonia emission measurements, with important implications for future modeling studies to clarify our understanding of urban amine budgets and to better constrain their climate and air quality effects.