Emission characteristics of reactive organic gases from industrial volatile chemical products (VCPs) in China
Abstract. Volatile chemical products (VCPs) have become an important source of reactive organic gases (ROGs) in urban areas worldwide. Industrial activities can also utilize a large amount of VCPs and emit many organic gases into the atmosphere. Due to multiple sampling and measurement challenges, only a subset of ROG species is usually measured for many industrial VCP sources. This study aimed to investigate the emissions of ROGs from five industrial VCP sources in China, including shoemaking, plastic surface coating, furniture coating, printing, and ship coating industries. More comprehensive speciation of ROG emissions from these industrial VCP sources was developed by the combination of the proton transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS) along with gas chromatography-mass spectrometer/flame ionization detector (GC-MS/FID). Our study identified oxygenated ROG species (OVOCs) as representative ROGs emitted from these sources, which are highly related to specific chemicals used during the industrial activities. Moreover, mass spectra similarity analysis revealed significant dissimilarities among the ROG emission sources, indicating substantial variations between different industrial VCP sources. Except for the ship coating industry utilizing solvent-borne coatings, the proportions of OVOCs range from 67 % to 96 % in total ROG emissions and 72 % to 97 % in total OH reactivity (OHR) for different industrial sources. The industrial VCP sources associated with solvent-borne coatings exhibited a higher ozone formation potential (OFP), reaching as high as 5.5 and 2.7 g O3·g-1 ROGs for ship coating and furniture coating industries, primarily due to contributions from aromatics. The fractions of the ten most abundant species in total ROG emissions, OHR, and OFP indicated a highly centralized of ROG emissions from various industrial VCP sources. Our results suggest that ROG treatment devices may have limited effectiveness for all ROGs, with treatment efficiencies ranging from -12 % to 68 %. Furthermore, we found that ROG pairs (e.g., methyl ethyl ketone (MEK) /C8 aromatics ratio) could serve as effective indicators for distinguishing industrial VCP sources, particularly for measurements in industrial areas. Our study demonstrated the importance of measuring a large number of ROGs using PTR-ToF-MS for characterizing ROG emissions from industrial VCP sources.
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