An overview of optical and thermal methods for the characterization of carbonaceous aerosol

Abstract

Carbon is present in the atmosphere not only as $$\hbox {CO}_2$$ CO 2 and other gaseous compounds: it is also one of the major components of the atmospheric aerosols. Carbonaceous Aerosols, CA, have a high but still not fully understood impact on climate and human health, furthermore, their composition is part of the “fingerprint” characteristic of different “sources” of airborne Particulate Matter (PM). The set of methodologies to quantify the concentration of specific carbonaceous species in the atmospheric aerosols is extremely ample, however a completely assessed standard has not been defined yet. In this review article we summarize the state of the art in such wide and multi-disciplinary field, with a focus on optical and thermo-optical methodologies and insights on the more relevant open problems.

Reply on RC4

“…The optical properties of the MISG aerosol were determined in terms of the absorption coefficient (b_abs; i.e. the absorbance per unit length) (Massabò and Prati, 2021). The b_abs definition applies both to measurements directly performed on the aerosol dispersed in the atmosphere (by PAXs, in this work) and to off-line analyses on aerosol sampled on filters (by MWAA, in this work), provided a proper data reduction is adopted (Massabò and Prati, 2021;and references therein).…”

A New PM Sampler with a Built-In Black Carbon Continuous Monitor

“…The World Health Organization (WHO) included atmospheric particulate air pollution in the list of the most severe public health issues, mainly impacting in urban areas [1]. Carbonaceous aerosols are a major component of atmospheric particulate matter with significant impacts on health as well as on the total environment [2]. While present regulations [3] are worldwide based on the monitoring of the atmospheric concentration of PM10 and PM2.5 (i.e., mass concentration of particulate matter, PM, with aerodynamic diameter ≤ 10 and 2.5 µm, respectively), the monitoring of the carbonaceous species inside the PM is more and more requested, even in view of possible new metrics to adopt for human health protection [4].…”

“…The literature on the measuring methodologies and equipment for carbonaceous aerosol is extremely wide with several comprehensive review articles [2,18,19]. So far, instruments to sample the PM on filters according to the standard regulations and on-line monitoring of the concentration of carbonaceous species (Elemental Carbon, EC, Organic Carbon, OC and Black Carbon, BC) have been separately and independently developed.…”

“…In the last years, the Multi Wavelength Absorbance Analyzer, MWAA, [22,23] has been developed with the aim of performing a firm, non-destructive, black and brown carbon (BrC) determination [2,18,19] on PM samples collected on filter media. Brown carbon corresponds to a class of organic light-absorbing carbonaceous compounds with an imaginary part of the refractive index that increases moving toward short-visible and UV wavelengths [19], this resulting in a brownish or yellowish appearance.…”

“…The coupling of optical and thermo-optical analyses offers several advantages as the possibility to retrieve the MAC value [2,18,19] of the PM in a particular site [23] and to improve the accuracy in the OC/EC separation [23]. Finally, not neglecting the partial mismatching between BC and EC, the OC concentration could be simply determined as OC = TC − BC, with TC = total carbon retrieved from the thermal analysis only and BC determined by optical absorption.…”