Accelerator mass spectrometric determination of carbon-14 in the low-polarity organic fraction of atmospheric particles

Polycyclic aromatic hydrocarbons and other low-polarity organic compounds (LPCs) were isolated from fine atmospheric particles collected in Albuquerque, NM, during December 1985. A procedure for removing solvent and oxidizing the LPC samples to CO{sub 2} was developed. Recovery for the most volatile compound studied (phenanthrene) was > 90%, and the procedural blank was 0.98 {plus minus} 0.06 {mu}g of C (standard error, SE, for n = 5 replicates). Sixteen samples, each containing the LPC fraction from a different aerosol sample, were prepared by this method and converted to targets for accelerator mass spectrometry. The {sup 14}C/{sup 13}C ratio was measured for each target. Samples contained 38-470 {mu}g of C. High beam currents (0.4-3.7 {mu}A) and good Poisson statistics (> 900 counts) were obtained. The {sup 14}C data were used to calculate the contribution of residential wood combustion (RWC) to LPC levels in the Albuquerque atmosphere. At a residential site, RWC contributed 81 {plus minus} 1% (SE, n = 6) to the nighttime LPCs and 60 {plus minus} 8% (SE, n = 3) to daytime LPCs. At a roadway intersection, the RWC contribution was 74 {plus minus} 3% (SE, n = 5) at night and 47 {plus minus} 7% (SE, n = 2) during the day.