Table 1.
Experiment Casesa | Add H2O2 | Reaction Time Before Making Aerosols | UV Radiation | Acidic Aerosols | Number Fraction of Generated Aerosols is Acidic | Number Fraction of Acid Aerosols Containing m/z 155 | Relative Peak Area at m/z 155 in Acidic Particles | Acid Particle Mode Diameters (µm) |
---|---|---|---|---|---|---|---|---|
A. Glyoxal + NH4HSO4 + H2SO4 | no | <1 h | no | yes | 0.17 | 0 | 0 | 0.5 |
B. Glyoxal + NH4HSO4 + H2SO4 | no | 4 days | no | yes | 0.47 | 0.01 | 2 × 10−4 | 0.6 (82%) and 1.8 (18%) |
C. Glyoxal + NH4HSO4 + H2SO4 | no | <6 h | 5 h | 0.54 | 0.03 | 3 × 10−4 | 0.6 (80%) and 2.0 (20%) | |
D. Glyoxal + NH4HSO4 + H2SO4 | no | 6 days | 5 h | yes | 0.68 | 0.11 | 3.5 × 10−4 | 1 (23%) and 2.3 (78%) |
E. Glycolic acid + NH4HSO4 + H2SO4 | no | 1 day | no | yes | 0.90 | 0.28 | 1.5 × 10−3 | 0.6 (44%) and 2.0 (56%) |
F. Glycolic acid + NH4HSO4 + H2SO4 | yes | New (<2 h) | 75 min | yes | 0.69 | 0.53 | 6 × 10−3 | 0.6 (10%) and 2.0 (90%) |
G. Glycolic acid + (NH4)2SO4 + H2SO4 | yes | New (<2 h) | 40 min | Less acidic pH = 3 | 0.1 | 0.02 | 8 × 10−4 | distributed between 0.5 and 2.0 |
H. Glycolic acid + NH4HSO4 + H2SO4 | yes | 1 day | 75 min | yes | 0.91 | 0.41 | 3 × 10−3 | 1.6 |
The solutions were exposed to lab light in the daytime after they were made.