VOCs emission profiles from rural cooking and heating in Guanzhong Plain, China and its potential effect on regional O₃ and SOA formation

Abstract. Solid fuels (i.e., biomass fuel and coal) burning for cooking and heating emit large amounts of pollutants into atmosphere including particulate matter (PM) and volatile organic compounds (VOCs). In this study, VOCs were directly collected in chimneys of residential cooking and heating stoves in Guanzhong Plain using adsorbent tube approach followed by thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS) analysis. Emission factors (EFs) of targeted VOCs varied from 47.2 ± 19.4 to 3121.3 ± 1592.4 mg kg⁻¹ which had a descending order of biomass straw > woody fuel >> coal fuels. A remarkable finding is that semi-gasifier could not suppress the VOCs emission even though a high efficiency in reduction of PM was demonstrated. In addition, high values of coefficients of divergence (CD) (most > 0.5) support that there were large variations on the VOC profiles with different fuels and stoves. Ozone formation potential (OFP) of VOCs from solid fuel burning ranged from 50.3 ± 19.6 to 5914.8 ± 1340.5 mg kg⁻¹, contributing ~ 20 % of ozone formation in Guanzhong atmosphere. The values were much larger than the contribution from PM of 6.7 %. However, much lower secondary organic aerosol formation potentials (SOAP) (0.5 ± 0.2–45.6 ± 3.0 mg kg⁻¹) of VOCs emitted from solid fuel burning were estimated. The values were two orders of magnitude lower than OFP and only accounted for 0.23 % of the SOA in Guanzhong in 2013. The results of this study demonstrated that the VOCs emission from solid fuel burning had a strong impact to the ozone pollution in Guanzhong Plain.