Emissions of nonmethane volatile organic compounds from open crop residue burning in the Yangtze River Delta region, China

Abstract

Open crop residue burning is one of the major sources of air pollutants including the precursors of photooxidants like ozone and secondary organic aerosol. We made measurements of trace gases including nonmethane volatile organic compounds (NMVOCs) in a rural area in central East China in June 2010. During the campaign, we identified six biomass burning events in total through the simultaneous enhancement of carbon monoxide and acetonitrile. Four cases represented fresh plumes (<2 h after emission), and two cases represented aged plumes (>3 h after emission), as determined by photochemical age. While we were not able to quantify formic acid, we identified an enhancement of major oxygenated volatile organic compounds (OVOCs) as well as low molecular alkanes and alkenes, and aromatic hydrocarbons in these plumes. The observed normalized excess mixing ratios (NEMRs) of OVOCs and alkenes showed dependence on air mass age, even in fresh smoke plumes, supporting the view that these species are rapidly produced and destructed, respectively, during plume evolution. Based on the NEMR data in the fresh plumes, we calculated the emission factors (EFs) of individual NMVOC. The comparison to previous reports suggests that the EFs of formaldehyde and acetic acid have been overestimated, while those of alkenes have been underestimated. Finally, we suggest that open burning of wheat residue in China releases about 0.34 Tg NMVOCs annually. If we applied the same EFs to all crops, the annual NMVOC emissions would be 2.33 Tg. The EFs of speciated NMVOCs can be used to improve the existing inventories.

Emission characteristics of refractory black carbon aerosols from fresh biomass burning: a perspective from laboratory experiments

“…The competing condensing processes under nucleirich conditions resulted in relatively thin coatings on the rBC particles, instead of direct formation of particulate organic matter. Previous studies (Kudo et al, 2014;Inomata et al, 2015) also found that the emission factor of NMVOCs during the flaming stage was lower by an order of magnitude than that during the smoldering stage. It also supported our conclusion that the thinly coated rBC particles associated with mode no.…”

Diagnosis of Photochemical Ozone Production Rates and Limiting Factors in Continental Outflow Air Masses Reaching Fukue Island, Japan: Ozone-Control Implications

“…Formaldehyde concentrations were determined by using the detection sensitivity reported previously (Inomata et al, 2008). For MEK, the volume mixing ratio was calculated theoretically from the equationobtained signal intensity, rate constant, and reaction time for its protonation reaction (Inomata et al, 2010;Kudo et al, 2014). Isoprene (ISO) concentrations were not determined in 2009 and were estimated from 2010 data, parameterized as a function of solar light intensity and ambient temperature.…”

Observed and Modeled Mass Concentrations of Organic Aerosols and PM2.5 at Three Remote Sites around the East China Sea: Roles of Chemical Aging

“…The OH radical concentrations during the three field campaign periods were estimated, based on a photochemical box model, constrained by comprehensive observations of gases (ozone, CO, NO, NO 2 , volatile organic compounds (VOCs), and oxygenated volatile organic compounds (OVOCs)) and J values. The average O 3 , CO, benzene, and propane concentrations were 56.8, 189, 0.14, and 0.27 ppbv for Fukue (Kanaya et al, 2016a), 56.1, 403, 1.0, and 1.2 ppbv for Rudong (Kudo et al, 2014;Pan et al, 2015), and 43.1, 172, 0.12, and 0.52 ppbv for Jeju. Briefly, using the Regional Atmospheric Chemistry Mechanism version 2 (RACM2, Goliff et al, 2013), OH concentrations were determined from the balance of production and loss rates in a time-dependent manner.…”

“…Typical transportation time from the continent during the springsummer season was 10-60 h (Kanaya et al, 2016b). The Rudong site is ~100 km north of Shanghai, and just 2 km west of the East China Sea coastline (Pan et al, 2012;Kudo et al, 2014). The major activity in the surrounding area is agriculture, and local sources of aerosols and precursor gases are limited.…”