scholarly journals Secondary Organic Aerosol Formation From Isoprene Epoxides in the Pearl River Delta, South China: IEPOX‐ and HMML‐Derived Tracers

2018 ◽  
Vol 123 (13) ◽  
pp. 6999-7012 ◽  
Author(s):  
Quan‐Fu He ◽  
Xiang Ding ◽  
Xiao‐Xin Fu ◽  
Yu‐Qing Zhang ◽  
Jun‐Qi Wang ◽  
...  
2019 ◽  
Author(s):  
Zhenfeng Wu ◽  
Yanli Zhang ◽  
Junjie He ◽  
Hongzhan Chen ◽  
Xueliang Huang ◽  
...  

Abstract. Limiting the fuel sulfur content (FSC) is a widely adopted approach to reduce ship emissions of sulfur dioxide (SO2) and particulate matters (PM) particularly in emission control areas (ECA), but its impact on the emission of volatile organic compounds (VOCs) is still not well understood. In this study, emissions from ships at berth in Guangzhou, south China, were characterized before and after implementing the fuel switch policy with a FSC limit of 0.5 % in the Pearl River Delta ECA in south China. After implementing the fuel switch policy, the emission factors (EFs) of SO2 and PM2.5 for coastal vessels dropped by 78 % and 56 % on average, respectively; the EFs of non-methane hydrocarbons (NMHCs), however, reached 1807 ± 1746 mg/kg, about 15 times that of 118 ± 56.1 mg/kg before implementing the new policy. This dramatic increase in the emission of NMHCs might be largely due to the replacement of high-sulfur residual fuel oil with low-sulfur diesel or heavy oils, which are typically more rich in short-chain hydrocarbons. Moreover, reactive alkenes overtook alkanes to become the dominant group among NMHCs and low carbon number NMHCs, such as ethylene, propene and isobutane, became the dominant species after the new policy. As a result of the largely elevated EFs of reactive alkenes and aromatics after the new policy, for per kilogram of fuel burned, emitted NMHCs had nearly 29 times larger ozone formation potentials (OFPs) and about 2 times higher secondary organic aerosol formation potentials (SOAFPs). Unlike coastal vessels, river vessels in the region used diesel fuels all along and were not affected by the fuel switch policy, but their EFs of NMHCs were even 90 % larger than that of coastal vessels after implementing the new policy, with about 120 % larger fuel-based OFPs and 70–140 % larger SOAFPs. The results from this study suggest that while the fuel switch policy could effectively reduce SO2 and PM emissions and thus help combat PM2.5 pollution, it would also lead to greater emissions of reactive VOCs, that may threatens ozone pollution control in the harbor cities. This change for coastal or ocean-going vessels, along with the large amounts of reactive VOCs from river vessels, raises regulatory concerns for ship emissions of reactive VOCs.


2019 ◽  
Vol 19 (22) ◽  
pp. 14403-14415 ◽  
Author(s):  
Yu-Qing Zhang ◽  
Duo-Hong Chen ◽  
Xiang Ding ◽  
Jun Li ◽  
Tao Zhang ◽  
...  

Abstract. Secondary organic aerosol (SOA) formation from biogenic precursors is affected by anthropogenic emissions, which are not well understood in polluted areas. In this study, we accomplished a year-round campaign at nine sites in polluted areas located in the Pearl River Delta (PRD) region during 2015. We measured typical biogenic SOA (BSOA) tracers from isoprene, monoterpenes, and β-caryophyllene, as well as major gaseous and particulate pollutants and investigated the impact of anthropogenic pollutants on BSOA formation. The concentrations of BSOA tracers were in the range of 45.4 to 109 ng m−3 with the majority composed of products from monoterpenes (SOAM, 47.2±9.29 ng m−3), isoprene (SOAI, 23.1±10.8 ng m−3), and β-caryophyllene (SOAC, 3.85±1.75 ng m−3). We found that atmospheric oxidants, Ox (O3 plus NO2), and sulfate correlated well with later-generation SOAM tracers, but this was not the case for first-generation SOAM products. This suggested that high Ox and sulfate levels could promote the formation of later-generation SOAM products, which probably led to the relatively aged SOAM that we observed in the PRD. For the SOAI tracers, both 2-methylglyceric acid (NO/NO2-channel product) and the ratio of 2-methylglyceric acid to 2-methyltetrols (HO2-channel products) exhibit NOx dependence, indicating the significant impact of NOx on SOAI formation pathways. The SOAC tracer was elevated in winter at all sites and was positively correlated with levoglucosan, Ox, and sulfate. Thus, the unexpected increase in SOAC in wintertime might be highly associated with the enhancement of biomass burning, O3 chemistry, and the sulfate component in the PRD. The BSOAs that were estimated using the SOA tracer approach showed the highest concentration in fall and the lowest concentration in spring with an annual average concentration of 1.68±0.40 µg m−3. SOAM dominated the BSOA mass all year round. We also found that BSOA correlated well with sulfate and Ox. This implied a significant effect from anthropogenic pollutants on BSOA formation and highlighted that we could reduce BSOA by controlling the anthropogenic emissions of sulfate and Ox precursors in polluted regions.


Geothermics ◽  
2021 ◽  
Vol 96 ◽  
pp. 102164
Author(s):  
Zheng-An Wei ◽  
Haibing Shao ◽  
Ling Tang ◽  
Bin Deng ◽  
Hailong Li ◽  
...  

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