Characterizing elemental, equivalent black, and refractory black carbon aerosol particles: a review of techniques, their limitations and uncertainties

Abstract

Elemental-, equivalent black- and refractory black-carbon are terms that have been defined in order to dissect the more general term, black carbon, into its component parts related to its specific chemical and optical properties and its impact on climate and health. Recent publications have attempted to clarify the meaning of these terms with respect to their environmental impact, particularly on climate. Here, we focus on the measurement aspects, reviewing the most commonly implemented techniques for the direct and indirect derivation of black carbon properties, their strengths, limitations, and uncertainties, and provide a non-exhaustive bibliography where the reader can find more detailed information. This review paper is designed as a guide for those wishing to learn about the current state of black carbon measurement instrumentation, how calibration is carried out, when one instrument may have the advantage over another, and where new techniques are needed to fill important knowledge gaps.

Seasonal Characteristics of Aerosol Black Carbon in Relation to Long Range Transport over Tripura in Northeast India

“…Black carbon (BC) is the by-product of incomplete combustion of carbonaceous fuel (of fossil fuels, biomass and agricultural wastes and forest fires). The most refractory and lightabsorbing component of carbonaceous combustion particles are synonymously referred as "black carbon", "soot", "elemental carbon", "equivalent black carbon" and "refractory black carbon", but the underlying definitions and measurement methods are different (Petzold et al, 2013;Lack et al, 2014). In the present study, we have used optical technique for the measurement of Black Carbon (BC).…”

Estimation of black carbon emissions from Siberian fires using satellite observations of absorption and extinction optical depths

“…The eBC measurements were calibrated against gravimetric measurements of BC mass concentration, using BC particles produced by 10 a pyrolysis generator. It should be noted that the accuracy of aethalometer measurements may be affected by several factors, including the SSA of real aerosol particles, particle size, composition and filter loading (see, e.g., Liousse et al, 1993;Sharma et al, 2002;Lack et al, 2014). In particular, the eBC concentration may be strongly overestimated due to greater light scattering by real aerosol particles compared to scattering by the soot particles used in the calibration procedure, although this effect can be counterbalanced by lower attenuation for larger filter loadings (see, e.g., Weingartner et al, 15 2003).…”

“…In view of the above rather controversial findings and the important role that BC emissions from BB are likely to play in climate processes in the Arctic, it is critical to obtain stronger observational constraints on BC emissions from fires in northern Eurasia and its major BB BC source regions such as Siberia. 25 Note that the general term "black carbon", which is used throughout this paper, is rather generic and can be broken down into more specific terms, including refractory black carbon (rBC), elemental carbon (EC), and equivalent black carbon (eBC); these terms refer to three major measurement approaches which are used to characterize carbonaceous matter, such as laserinduced incandescence, thermal or thermal optical methods distinguishing between more and less volatile fractions of carbonaceous aerosol material, and optical methods based on measurements of light-absorption coefficients (Andreae and 30 Gelencsér, 2006;Bond et al, 2013;Petzold et al, 2013;Lack et al, 2014). Accordingly, BC emission data reported by a given emission inventory may be based on one or more specific methods that were employed to evaluate the emission factors used in the inventory.…”

“…15 The main difficulty in using the OMI AAOD retrievals for constraining BC emissions stems from the well-established fact (see, e.g., Andreae and Gelencsér, 2006;Jethva and Torres, 2011;Bahadur et al, 2012;Mok et al, 2016) that the absorption of UV and shortwave visible radiation by BB aerosol is strongly affected by brown carbon (that is, by the light-absorbing fraction of organic carbon). In view of this fact, explicit modeling of AAOD in the case of BB aerosol as a function of its composition would inevitably involve major uncertainties associated with the assumptions regarding the magnitude of the 20 imaginary part of the refractive index for organic carbon (OC) and the mixing state of aerosol particles; these characteristics are likely strongly variable, depending on sources and atmospheric processing of BB aerosol (Lack et al, 2012, Saleh et al, 2013Wong et al, 2017). To overcome this difficulty, we follow an empirical approach (Konovalov et al, 2017a) that involves parameterization of AAOD as a function of the EC/OC (elemental carbon to organic carbon) ratio and the aerosol extinction optical depth (AOD).…”

Real-time analysis of insoluble particles in glacial ice using single-particle mass spectrometry

“…More recent SP2 studies have highlighted the necessity of quantifying instrumental errors and systematic uncertainties when extracting trace amounts of highly heterogeneous material from snow and ice (Schwarz et al, 2012;Ohata et al, 2013;Wendl et al, 2014). Specifically, these studies have shown that correction factors, primarily a result of the efficacy achieved in nebulizing insoluble particles from a melted ice core matrix and aerodynamically delivering them to the SP2 for analysis, can be large and vary significantly between laboratory setups (Lack et al, 2014;Katich et al, 2017).…”