Abstract. Volatile organic compounds (VOCs) are key precursors of
photochemical smog. Quantitatively evaluating the contributions of VOC
sources to ozone (O3) formation could provide valuable information for
emissions control and photochemical pollution abatement. This study analyzed
continuous measurements of VOCs during the photochemical season in 2014 at a
receptor site (Heshan site, HS) in the Pearl River Delta (PRD) region, where
photochemical pollution has been a long-standing issue. The averaged mixing
ratio of measured VOCs was 34±3 ppbv, with the largest contribution
from alkanes (17±2 ppbv, 49 %), followed by aromatics, alkenes
and acetylene. The positive matrix factorization (PMF) model was applied to
resolve the anthropogenic sources of VOCs, coupled with a
photochemical-age-based parameterization that better considers the
photochemical processing effects. Four anthropogenic emission sources were
identified and quantified, with gasoline vehicular emission as the most
significant contributor to the observed VOCs, followed by diesel vehicular
emissions, biomass burning and solvent usage. The O3 photochemical
formation regime at the HS was identified as VOC-limited by a photochemical
box model with the master chemical mechanism (PBM-MCM). The PBM-MCM model
results also suggested that vehicular emission was the most important source
to the O3 formation, followed by biomass burning and solvent usage.
Sensitivity analysis indicated that combined VOC and NOx emission
controls would effectively reduce incremental O3 formation when the
ratios of VOC-to-NOx emission reductions were > 3.8 for
diesel vehicular emission, > 4.6 for solvent usage, > 4.6 for biomass burning and 3.3 for gasoline vehicular emission. Based on
the above results, a brief review of the policies regarding the control of
vehicular emissions and biomass burning in the PRD region from a regional
perspective were also provided in this study. It reveals that different
policies have been, and continue to be, implemented and formulated and could help
to alleviate the photochemical pollution in the PRD region. Nevertheless,
evaluation of the cost-benefit of each policy is still needed to improve air
quality.