Improving VOCs control strategies based on source characteristics and chemical reactivity in a typical coastal city of South China through measurement and emission inventory

Abstract

In China, the corresponding control directives for volatile organic compounds (VOCs) have been based on primary emissions, rarely considering reactive speciation. To seek more effective VOCs control strategies, we investigated 107 VOC species in a typical coastal city (Beihai) of South China, from August to November 2018. Meanwhile, a high-resolution anthropogenic VOCs monthly emission inventory (EI) was established for 2018. For source apportionments (SAs) reliability, comparisons of source structures derived from positive matrix factorization (PMF) and EI were made mainly in terms of reaction losses, uncertainties and specific ratios. Finally, for the source–end control, a comprehensive reactivity control index (RCI) was established by combing SAs with reactive speciation profiles. Ambient measurements showed that the average concentration of VOCs was 26.38 ppbv, dominated by alkanes (36.7%) and oxygenated volatile organic compounds (OVOCs) (29.4%). VOC reactivity was estimated using ozone formation potential (52.35 ppbv) and propylene-equivalent concentration (4.22 ppbv). EI results displayed that the entire VOC, OFP, and propylene-equivalent emissions were 40.98 Gg, 67.98 Gg, and 105.93 Gg, respectively. Comparisons of source structures indicated that VOC SAs agreed within ±100% between two perspectives. Both PMF and EI results showed that petrochemical industry (24.0% and 33.0%), food processing and associated combustion (19.1% and 29.2%) were the significant contributors of anthropogenic VOCs, followed by other industrial processes (22.2% and 13.3%), transportation (18.9% and 12.0%), and solvent utilization (9.1% and10.5%). Aimed at VOCs abatement according to RCI: for terminal control, fifteen ambient highly reactive species (predominantly alkenes and alkanes) were targeted; for source control, the predominant anthropogenic sources (food industry, solvent usage, petrochemical industry and transportation) and their emitted highly reactive species were determined. Particularly, with low levels of ambient VOC and primary emissions, in this VOC and NOx double-controlled regime, crude disorganized emission from food industry contributed a high RCI.

Ozone pollution mitigation in guangxi (south China) driven by meteorology and anthropogenic emissions during the COVID-19 lockdown

“…In previous years (2016–2019), the significant positive correlation with NO 2 in daily resolution, instead of negative correlations in hourly, showed that increased O 3 concentrations are highly associated with increased daily emissions of O 3 precursors. During the lockdown period in 2020, O 3 showed a strong positive correlation with NO 2 in daily resolution (r s = 0.375, p < 0.01), and a moderate positive correlation in hourly resolution (r s = 0.106, p < 0.05), indicating, unlike previous studies ( Fu et al, 2020 ), that O 3 concentrations were more likely to depend on NOx concentrations. Besides variabilities in its precursors, as a secondary photochemical pollutant, fluctuations in O 3 concentrations can also be driven by changes in meteorological conditions, which will be detailed below.…”

“…In particular, Beihai was most frequently affected by onshore air masses (Clusters 1 and 2, 58%), followed by Chongzuo (Clusters 1 and 3, 45%), Yulin (Clusters 1 and 3, 31%) and Nanning (Cluster 3, 24%). In view of the clean air from the South China Sea ( Fu et al, 2020 ) and lower O 3 concentrations in Southern Guangxi cities ( Fig. S1 ), we could conclude that the regional transport of air masses facilitated the overall decline in O 3 in Southern Guangxi.…”

“…With the VOC-limited regimes in most regions of China ( Wang et al, 2017 ), the national increase in O 3 could be linked to the decreased NOx, in addition to the increased VOCs/NOx ratio. On the contrary, in Beihai—classified as a transitional regime (VOCs/NOx ∼ 8:1) based on the 2018 measurements ( Fu et al, 2020 ), the VOCs/NOx ratio was expected to greatly exceed the transitional threshold from double-controlled regime to NOx-limited (VOCs/NOx > 12) under the lockdown. Based on the assumption, the drop in NOx concentrations contributed to the decline in O 3 concentrations in this region of South China.…”

Spatial and Temporal Distributions and Sources of Anthropogenic NMVOCs in the Atmosphere of China: A Review

“…As shown in Fig. 7, their contributions to the total OFP are different in different areas (Duan et al, 2008;Deng et al, 2019;Fu et al, 2020;Zhao et al, 2020;Zhou et al, 2020;Zhu et al, 2020). Contributions of the top eight NMVOCs to OFP account for 51%−69% of the total, among which OVOCs, especially formaldehyde and acetaldehyde, contribute more to OFP in megacities.…”

Process-based VOCs Source Profiles and Contributions to Ozone Formation in Typical Organic Solvent-used Industries in Hangzhou

“…Therefore, studying the emission characteristics and atmospheric chemical activity of anthropogenic VOCs emission source is an important basis for understanding the formation mechanism of air pollution and devising effective control policies (Li et al, 2020). In addition, source profiles especially the localized are important for source apportionment, which could provide data in support of air quality model simulation and air pollution control strategies (Song et al, 2008;Fu et al, 2020).…”