Carbonaceous aerosols emitted from light-duty vehicles operating on gasoline and ethanol fuel blends.
This study examines the chemical properties of carbonaceous aerosols emitted from three light-duty gasoline vehicles (LDVs) operating on gasoline (e0) and ethanol-gasoline fuel blends (e10 and e85). Vehicle road load simulations were performed on a chassis dynamometer using the three-phase LA-92 unified driving cycle (UDC). Effects of LDV operating conditions and ambient temperature (-7 and 24 °C) on particle-phase semivolatile organic compounds (SVOCs) and organic and elemental carbon (OC and EC) emissions were investigated. SVOC concentrations and OC and EC fractions were determined with thermal extraction-gas chromatography-mass spectrometry (TE-GC-MS) and thermal-optical analysis (TOA), respectively. LDV aerosol emissions were predominantly carbonaceous, and EC/PM (w/w) decreased linearly with increasing fuel ethanol content. TE-GC-MS analysis accounted for up to 4% of the fine particle (PM2.5) mass, showing the UDC phase-integrated sum of identified SVOC emissions ranging from 0.703 μg km(-1) to 18.8 μg km(-1). Generally, higher SVOC emissions were associated with low temperature (-7 °C) and engine ignition; mixed regression models suggest these emissions rate differences are significant. Use of e85 significantly reduced the emissions of lower molecular weight PAH. However, a reduction in higher molecular weight PAH entities in PM was not observed. Individual SVOC emissions from the Tier 2 LDVs and fuel technologies tested are substantially lower and distributed differently than those values populating the United States emissions inventories currently. Hence, this study is likely to influence future apportionment, climate, and air quality model predictions that rely on source combustion measurements of SVOCs in PM.
Office of Research and Development National Risk Management Research Laboratory, United States Environmental Protection Agency , Research Triangle Park, North Carolina 27711, United States.
Michael D
MD
Hays
William
W
Preston
Barbara J
BJ
George
Judy
J
Schmid
Richard
R
Baldauf
Richard
R
Snow
James R
JR
Robinson
Thomas
T
Long
James
J
Faircloth
D000336:Aerosols / Q000032:analysis*; D002244:Carbon / Q000032:analysis*; D000431:Ethanol / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D005742:Gasoline; D018986:Motor Vehicles; D055620:Optical Phenomena; D052638:Particulate Matter / Q000032:analysis; D013696:Temperature; D014481:United States; D001335:Vehicle Emissions / Q000032:analysis*; D055549:Volatile Organic Compounds / Q000032:analysis
D000336:Aerosols; D005742:Gasoline; D052638:Particulate Matter; D001335:Vehicle Emissions; D055549:Volatile Organic Compounds; D000431:Ethanol; D002244:Carbon