Abstract. In the present work, we performed chassis dynamometer experiments to
investigate the emissions and secondary organic aerosol (SOA) formation
potential of intermediate-volatility organic compounds (IVOCs) from an
on-road Chinese gasoline vehicle. High IVOC emission factors (EFs) and
distinct volatility distribution were recognized. The IVOC EFs for the
China V vehicle ranged from 12.1 to 226.3 mg per kilogram fuel, with
a median value of 83.7 mg per kilogram fuel, which was higher than
that from US vehicles. Besides, a large discrepancy in volatility distribution
and chemical composition of IVOCs from Chinese gasoline vehicle exhaust was
discovered, with larger contributions of B14–B16 compounds
(retention time bins corresponding to C14-C16 n-alkanes) and a higher
percentage of n-alkanes. Further we investigated the possible reasons that
influence the IVOC EFs and volatility distribution and found that fuel
type, starting mode, operating cycles and acceleration rates did have an
impact on the IVOC EF. When using E10 (ethanol volume ratio of 10 %, v/v)
as fuel, the IVOC EF of the tested vehicle was lower than that using
commercial China standard V fuel. The average IVOC-to-THC (total hydrocarbon) ratios for
gasoline-fueled and E10-fueled gasoline vehicles were 0.07±0.01 and
0.11±0.02, respectively. Cold-start operation had higher IVOC EFs
than hot-start operation. The China Light-Duty Vehicle Test Cycle (CLTC) produced
70 % higher IVOCs than those from the Worldwide Harmonized Light Vehicles
Test Cycle (WLTC). We found that the tested vehicle emitted more IVOCs at
lower acceleration rates, which leads to high EFs under CLTC. The only
factor that may influence the volatility distribution and compound
composition is the engine aftertreatment system, which has compound and
volatility selectivity in exhaust purification. These distinct
characteristics in EFs and volatility may result in higher SOA formation
potential in China. Using published yield data and a surrogate equivalent
method, we estimated SOA formation under different OA (organic aerosol) loading and NOx
conditions. Results showed that under low- and high-NOx conditions at
different OA loadings, IVOCs contributed more than 80 % of the predicted
SOA. Furthermore, we built up a parameterization method to simply estimate
the vehicular SOA based on our bottom-up measurement of VOCs (volatile organic compounds) and IVOCs,
which would provide another dimension of information when considering the
vehicular contribution to the ambient OA. Our results indicate that
vehicular IVOCs contribute significantly to SOA, implying the
importance of reducing IVOCs when making air pollution controlling policies
in urban areas of China.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.