Sources of volatile organic compounds and policy implications for regional ozone pollution control in an urban location of Nanjing, East China

Abstract

Abstract. Understanding the composition, temporal variability and source apportionment of volatile organic compounds (VOCs) is necessary for determining effective control measures to minimize VOCs and their related photochemical pollution. To provide a comprehensive analysis of VOC sources and their contributions to ozone (O3) formation in the Yangtze River Delta (YRD) – a region experiencing the highest rates of industrial and economic development in China – we conducted a 1-year sampling exercise using a thermal desorption GC (gas chromatography) system for the first time at an urban site in Nanjing (JAES site). Alkanes were the dominant group at the JAES site, contributing ∼53 % to the observed total VOCs, followed by aromatics (∼17 %), acetylene (∼17 %) and alkenes (∼13 %). We identified seasonal variability in total VOCs (TVOCs) with maximum and minimum concentrations in winter and summer, respectively. Morning and evening peaks and a daytime trough were identified in the diurnal VOC patterns. We identified VOC sources using positive matrix factorization (PMF) and assessed their contributions to photochemical O3 formation by calculating the O3 formation potential (OFP) based on the mass concentrations and maximum incremental reactivities of VOCs. The PMF model identified five dominant VOC sources, with highest contributions from diesel vehicular exhaust (34±5 %), followed by gasoline vehicular exhaust (27±3 %), industrial emissions (19±2 %), fuel evaporation (15±2 %) and biogenic emissions (4±1 %). The results of the OFP calculation inferred that VOCs from industrial and vehicular emissions were found to be the dominant precursors for OFP, particularly the VOC species of xylenes, toluene and propene, and top priority should be given to these for the alleviation of photochemical smog. Our results therefore highlight that priority should be given to limited VOC sources and species for effective control of O3 formation in Nanjing.

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.…”

Nitrogen oxides and ozone in urban air: A review of 50 plus years of progress

“…Air Act has shown that the benefit/cost ratio exceeds 40/1. 24 49 In Beijing, this measure of ozone has been larger with values just below 100 ppb in recent years. 52 The United Nations report on air pollution in Beijing states "Ozone pollution has not been effectively controlled in recent years".…”

“…63 China is moving forward with new regulations designed to reduce VOC emissions. 20,49 Recent research shows that ozone generation in Nanjing can be reduced by controlling VOC emissions. 49 A study of sources of VOC emissions shows that many of the emissions are associated with transportation.…”

“…20,49 Recent research shows that ozone generation in Nanjing can be reduced by controlling VOC emissions. 49 A study of sources of VOC emissions shows that many of the emissions are associated with transportation. 49 Monitoring of VOC concentrations is Public education and citizen participation are important in efforts to increase community will to improve air quality.…”

“…49 A study of sources of VOC emissions shows that many of the emissions are associated with transportation. 49 Monitoring of VOC concentrations is Public education and citizen participation are important in efforts to increase community will to improve air quality. 35 The regulations on emissions need to be for the entire geographical area of the air shed, and they need to be enforced effectively on a continuing basis with updates to address emissions that should be added.…”