Organic Fingerprints of Condensable Particulate Matter from Ultralow Emission Stationary Sources in China

Understanding organics in condensable particulate matter (CPM) from stationary sources is crucial for assessing air quality impacts, especially as CPM gains significance due to reductions in regulated PM and the implementation of ultralow emission standards in China. Knowledge of these organics remains limited as traditional targeted analyses potentially overlook important molecules and their atmospheric impacts. Here, we employed comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC × GC-TOFMS) to analyze the molecular compositions of organics in CPM from typical ultralow emission coal-fired power plants and iron and steel sintering plants in China. We established a nontargeted screening approach to obtain molecular fingerprints of these organics, identifying more than 180 and 200 compounds from over 1000 peaks from the two types of plants. Key contributors to CPM organics include substituted benzenes, polyfunctional aliphatic compounds, alkanes, and cycloalkanes, differing from the previously reported alkane dominance observed using traditional one-dimensional GC analysis. Intermediate/semivolatile organic compounds (I/SVOCs) dominate organics in CPM, with a significant fraction of low volatile organic compounds detected especially in iron and steel sintering plant emissions. Iron and steel sintering plants emit higher concentrations of organics in CPM, particularly aromatics, due to their lower combustion efficiency in the sintering processes. These findings enhance our understanding of the atmospheric behavior of organics in CPM and their impacts on air quality.