Consistency and Traceability of Black Carbon Measurements Made by Laser-Induced Incandescence, Thermal-Optical Transmittance, and Filter-Based Photo-Absorption Techniques

In this study, we show that black carbon (BC) mass concentrations measured by different techniques are consistent and traceable. First, we present the volatilities of 13 organic compounds passed through a heated inlet. These data were used to quantify the interference of organic aerosols on the BC measurement techniques. The masses of the refractory particles that incandesce (m*(ref)) were used to calibrate BC mass measured by a single-particle soot photometer (SP2), which uses laser-induced incandescence. This calibration was influenced little by refractory organics and agreed well with that of fullerene soot, which indicates the consistency of the standards. We estimated the interference of pyrolyzed refractory organics on the BC measured with a filter-based absorption photometer continuous soot monitoring system (COSMOS) with a heated inlet to be small in Asia. This was also confirmed by the stable mass absorption cross section (MAC) obtained by the high correlations between BC mass concentrations measured by COSMOS (M-COSMOS) and those measured by the thermal-optical transmittance method (M-TOT) (Kondo et al. 2009). M-COSMOS was also compared with total BC mass concentrations measured with an SP2 (M-SP2) in Tokyo in 2009. M-COSMOS and M-SP2 were highly correlated (r(2) = 0.97) and agreed to within about 10% on average. These results demonstrate that M-SP2, M-COSMOS, and M-TOT were nearly identical. Use of the masses of incandescing refractory BC particles for calibration of BC mass concentrations determined by different techniques gave consistent results.