Closure between particulate matter concentrations measured ex situ by thermal–optical analysis and in situ by the CPMA–electrometer reference mass system

Abstract

The thermal-optical analysis (TOA) of black carbon in particulate matter (PM) collected on filters has been recommended and used for the calibration of mass-concentration instruments. However, filter-based TOA calibrations have substantial practical limitations, requiring high sample flow rates (>10 litres per minute), long sampling times (up to 3 h), and subsequently manual filter processing with long analysis times (>15 min per filter). These limitations are avoided by in situ calibration techniques such as the centrifugal particle mass analyzer (CPMA)-electrometer reference mass system (CERMS). The CERMS is capable of producing and monitoring in situ reference mass concentrations below 1 mg m À3 and in realtime ($1 Hz). Additional advantages of the CERMS are its improved repeatability (1.1%) over TOA (9-11%), and its measurement of a well-defined quantity: total post-CPMA suspended PM mass. In the present work, we demonstrate closure between these two techniques in terms of PM mass concentration for three different soot generators (viz., the Argonaut miniature inverted soot generator, Jing miniCAST, and National Research Council inverted-flame burner) under carefully controlled conditions. We also demonstrate the sensitivity of the CERMS by characterizing the limits of detection of a commercial laser-induced incandescence instrument and a photoacoustic instrument. Our data support the use of the CERMS with well-characterized PM sources to provide reference mass concentrations for the calibration of instruments measuring PM or black-carbon mass concentration.

Size-dependent mass absorption cross-section of soot particles from various sources

“…Scanning mobility particle sizers (SMPSs; TSI Inc., USA) were used to characterize the size distributions of the non-volatile particles measured downstream of a 350 °C catalytic stripper (CS015, Catalytic Instruments GmbH, Germany). Below this temperature, the volatile mass fraction of MISG [47] and mature miniCAST soot (i.e. miniCAST soot without fuel dilution by premixing with N2) [42,48] is negligible.…”

“…[46]. The general laboratory setup for the measurements performed at the NRC has been described previously [47]. S1).…”

“…We measured 𝑀 PM using the CPMA-Electrometer Reference Mass Standard (CERMS) [47,[50][51][52] shown in Figure 1. In the CERMS, sample particles are highly charged by a unipolar diffusion aerosol charger (UDAC, Cambustion, UK) before being transmitted to a centrifugal particle mass analyzer (CPMA, Cambustion, UK) and then a faraday cup aerosol electrometer (FCAE, TSI 3068B, TSI Inc., USA).…”

Comparison of co-located refractory black carbon (rBC) and elemental carbon (EC) mass concentration measurements during field campaigns at several European sites

“…Bologna 24.1 ± 6.4 17.8 ± 7.4 0.2 ± 0.3 −6.5 ± 1.9 118.6 ± 0.3 Cabauw 22.4 ± 4.9 19.7 ± 4.6 0.7 ± 0.3 −3.4 ± 1.0 127.2 ± 0.4 Melpitz summer 24.5 ± 8.5 20.5 ± 7.3 0.4 ± 0.3 −4.5 ± 3.7 142.9 ± 0.3 Melpitz winter 2.9 ± 2.1 2.5 ± 1.4 1.1 ± 0.4 −1.5 ± 1.5 227.9 ± 0.7 Palaiseau 20.3 ± 8.7 18.0 ± 7.0 2.5 ± 2.0 −4.9 ± 2.1 136.7 ± 0.3 (b atn,corr ) (Virkkula et al, 2007;Drinovec et al, 2015). The attenuation coefficient is greater than the absorption coefficient due to multi-scattering effects within the filter matrix, described with a proportionality constant C. From a pair of b atn,corr coefficients at two different wavelengths, λ 1 and λ 2 , it is possible to calculate the absorption Ångström exponent, AAE(λ 1 , λ 2 ), a coefficient commonly used to describe the spectral dependence of the aerosol light absorption coefficient (Moosmüller et al, 2009):…”

“…In the other campaigns, Aethalometer AE33 (Magee Scientific) instruments were used. These data did not need further correction since the algorithm developed by Drinovec et al (2015), which takes into account the filter loading effect, is incorporated into the instrument. However, the AE33 firmware correction was not working properly during the Bologna campaign.…”