Trends of non-methane hydrocarbons (NMHC) emissions in Beijing during 2002–2013

Abstract

Abstract. Non-methane hydrocarbons (NMHCs) play a critical role in the photochemical production of ozone (O3) and organic aerosols. Obtaining an accurate understanding on temporal trends of NMHC emissions is essential for predicting air quality changes and evaluating the effectiveness of current control measures. In this study, we evaluated temporal trends of anthropogenic NMHC emissions during August in Beijing based on ambient measurements during selected summer periods at an urban site in Beijing from 2002 to 2013. In the contrast to the results from the most recent inventory (Multi-resolution Emission Inventory for China, MEIC), which reported that anthropogenic NMHC emissions during August increased by 28% from 2004 to 2012, whereas mixing ratios of NMHCs measured at this urban site decreased by 37% during the same time period. A positive matrix factorization (PMF) model was applied to these NMHC measurements for source apportionment. The results showed that the relative contributions of vehicular exhaust and gasoline evaporation to measured NMHC concentrations decreased by 66% during August from 2004 to 2012, comparable to the relative decline of 67% for transportation-related NMHC emissions reported by the MEIC inventory. This finding indicates that the implementation of stricter emissions standards for new vehicles and specific control measures for in-use vehicles has been effective for reducing transportation-related NMHC emissions. In addition, the PMF results suggested that there were no significant temporal changes in NMHC concentrations from solvent use and industry during August from 2004 to 2012, in contrast with the rapid rate of increase (8.8% yr−1) reported by the MEIC inventory. To re-evaluate the NMHC emissions trends for solvent use and industry, annual variations in NMHC / NOx ratios were compared between ambient measurements at the PKU site and the MEIC inventory. In contrast to the significant rise in NMHC / NOx ratios from the MEIC inventory, the measured NMHC / NOx ratios declined by 14% during August from 2005 to 2012. The inferred NMHC / NOx ratios based on PMF results exhibited a comparable decline of 11% to measured ratios. These results indicate that the increase rate for NMHC emissions from solvent use and industry in Beijing might be overestimated in the current inventory; therefore, additional research is necessary to verify the NMHC emission trends for this source.

Significant increase of surface ozone at a rural site, north of eastern China

“…Unfortunately, no systematic VOC observations are available from the SDZ site so that we cannot prove this supposition conclusive. However, a large increase in the anthropogenic emissions of non-methane hydrocarbon (NMHC) can be inferred from the Multiresolution Emission Inventory for China (MEIC) (http://www.meicmodel.org) for Beijing in the period of 2004-2012, which supports our view, although the emission data are questioned by a recent study (Wang et al, 2015).…”

Effects of rigorous emission controls on reducing ambient volatile organic compounds in Beijing, China

“…The surrounding area of this site is mainly commercial and residential, and the major nearby emission source of sampling site was vehicular traffic. This site is considered to be representative of a typical urban environment in Beijing (Song et al, 2007;Zhang et al, 2014;Li et al, 2015b;Wang et al, 2015). To evaluate the effect of the control measures, the whole study was divided into two parts: non-control period (11-19 August 2015) and control period (20 August-3 September 2015).…”

Gasoline aromatics: a critical determinant of urban secondary organic aerosol formation

“…Therefore, the higher emission of aromatic VOCs will likely result in more SOA formation potential. Existing fuel-effect experimental and model studies have shown that high-aromatic fuel in gasoline fuel will lead to more emissions of primary PM as well as some aromatic VOCs (Zervas et al, 1999;EPA, 2013;Karavalakis et al, 2015;Wang et al, 2016), indicating the considerable potential impact of gasoline aromatic content on SOA production. Furthermore, though aromatic content in diesel fuel may have an insignificant impact on SOA formation (Gordon et al, 2014b), SOA production from gasoline vehicle is considered more sensitive to aromatic content than that from diesel vehicle (Jathar et al, 2013).…”