Absence of ¹⁴C in PM2.5 Emissions from Gasohol Combustion in Small Engines

PM2.5 combustion emissions from small engines (string trimmer and chainsaw) using gasoline containing biogenic ethanol were collected and analyzed for their ¹⁴ C content. The sampling methodology was designed to minimize potential bias from organic artifact effects. The ¹⁴ C in the PM2.5 emissions was found to be drastically smaller (approximately a factor of 40) than the ¹⁴ C amounts measured in the fuels. This suggests that the current method of using ¹⁴ C measurements on ambient aerosol to estimate the contribution from fossil fuel combustion will be little affected by increased use of ethanol-containing gasoline.

Acknowledgments

The United States Environmental Protection Agency through its Office of Research and Development managed and funded the research described here under Contract No. 68-D-00-269 to Bevilacqua-Knight, Inc. and Purchase Order No. 3D-5079-NTHX to Woods Hole Oceanographic Institution. It has been subjected to Agency review and approved for publication. We thank Jerry Faircloth, Mike Pleasant, Kevin Hicks, Jason Mills, and Richard Snow for their assistance in collecting the small engine samples. We also thank Li Xu and Dana Gerlach for their technical expertise and assistance with ¹⁴C analysis of the fuel and filter samples.

Notes

^a Average of two background measurements, adjusted for run duration.

^b One background measurement, adjusted for run duration.

^a Datum from Run 1.

^b Datum from Run 2.

^c Datum from Run 5.

¹ > 99% organic carbon (OC).