The Variation, Source, and Environmental Impact of Chloride Across China: Summarized Field Results Based on the Aerosol Mass Spectrometer (AMS)

Abstract Despite numerous field studies focusing on the chemical composition of particulate matter, systematic investigations on particulate chloride (Cl − ) are scarce in China. This study examines the spatiotemporal distribution, origin, and environmental impact of Cl − across China via compiling a comprehensive data set of submicron aerosol (PM 1 ) detected by the aerosol mass spectrometer (AMS). In addition, we integrated high‐time resolution aerosol composition data from AMS at six representative sites in China for more detailed insights. The mass concentration of Cl − across China is notably high (1.9 ± 2.7 μg m −3 ) in comparison to the global average (0.3 ± 1.0 μg m −3 ), with a distinguished N–S pattern (North > South) and a distinct seasonality (winter > other seasons). Three categories of Cl − diurnal variations were classified, suggesting the primary combustion emission and gas/particle partitioning are the main drivers for the dynamic variation of Cl − . The good correlation between Cl − and combustion tracers corroborates the assertion that coal and biomass combustion are the main anthropogenic sources of Cl − based on emission inventory. Furthermore, the quantified environmental impacts of Cl − on ammonium balances, aerosol liquid water content, and hygroscopicity were systematically explored. In extreme cases, the Cl − can enhance 100% ALWC during polluted periods, signifying its key role in impacting the physiochemistry of aerosols. The mutual promotion between Cl − and other environment effects was also found. In summary, this study enhances our understanding of the distribution, sources, and environmental effects of Cl − across China, indicating that Cl − should be systematically considered in elucidating environment effect of fine particles.