Spatiotemporal characteristics and source apportionment of intermediate volatility organic compounds in the riverside...

Riverside industrial parks are crucial for economic growth in regions like the Yangtze River Delta, but industrialization brings complex pollution emission issues, and the emissions of intermediate volatility organic compounds (IVOCs) from these parks are under-researched, hindering the implementation of effective regional pollution control strategies. This study quantified the emissions of IVOCs throughout morning, afternoon, and evening at four sites within and surrounding a representative riverside industrial park during the summer and winter sampling campaigns. The results showed that: (1) IVOC concentrations exhibited a diurnal decrease from morning to evening. Notably, these concentrations were significantly higher in summer, reaching 172 ± 25.0 μg/m³, than in winter (31.8 ± 2.45 μg/m³). We hypothesized that diurnal variations were correlated with anthropogenic activity cycles and meteorological conditions, whereas seasonal differences were associated with temperature and source emission characteristics; (2) Diurnal variations in chemical composition of IVOCs were found to be insignificant. Nevertheless, distinct seasonal differences became evident. Specifically, the average proportion of unresolved complex mixtures (UCM) was significantly lower in winter (58 %) as compared to that in summer (82 %). In contrast, polycyclic aromatic hydrocarbons (PAHs) showed a marked increase, rising from 1 % in summer to 6-7 % in winter; (3) Spatially, during summer, the concentrations of IVOCs were found to be elevated in the vicinity of the Yangtze River and petrochemical facilities. In contrast, the chemical composition of IVOCs demonstrated minimal variation across different locations; (4) Source apportionment analysis revealed that industrial processes and inland shipping were the dominant sources of summer IVOCs, contributing 22 % and 32 %, respectively. During winter, coal combustion emerged as the primary driver of emissions, accompanied by a decline in the contributions from shipping and industrial processes. Therefore, it is imperative to formulate targeted control measures grounded in the relevant source apportionment results.