Investigation of black and brown carbon multiple-wavelengthdependent light absorption from biomass and fossil fuel combustion source emissions

TitleInvestigation of black and brown carbon multiple-wavelengthdependent light absorption from biomass and fossil fuel combustion source emissions
Publication TypeJournal Article
Year of Publication2015
AuthorsMR Olson, MV Garcia, MA Robinson, P Van Rooy, MA Dietenberger, M Bergin, and JJ Schauer
JournalJournal of Geophysical Research
Volume120
Issue13
Start Page6682
Pagination6682 - 6697
Date Published01/2015
Abstract

© 2015. American Geophysical Union. All Rights Reserved. Quantification of the black carbon (BC) and brown carbon (BrC) components of source emissions is critical to understanding the impact combustion aerosols have on atmospheric light absorption. Multiple-wavelength absorption was measured from fuels including wood, agricultural biomass, coals, plant matter, and petroleum distillates in controlled combustion settings. Filter-based absorption measurements were corrected and compared to photoacoustic absorption results. BC absorption was segregated from the total light extinction to estimate the BrC absorption from individual sources. Results were compared to elemental carbon (EC)/organic carbon (OC) concentrations to determine composition’s impact on light absorption. Multiple-wavelength absorption coefficients, Angstrom exponent (6.9 to <1.0), mass absorption cross section (MAC), and Delta C (97 µgm-3 to ~0 µgm-3) were highly variable. Sources such as incense and peat emissions showed ultraviolet wavelength (370nm) BrC absorption over 175 and 80 times (respectively) the BC absorption but only 21 and 11 times (respectively) at 520nm wavelength. The bulk EC MACEC, λ (average at 520nm=9.0±3.7m2 g-1; with OC fraction <0.85 = ~7.5m2 g-1) and the BrC OC mass absorption cross sections (MACBrC,OC,λ) were calculated; at 370 nm ultraviolet wavelengths; the MACBrC,OC,λ ranged from 0.8m2 g-1 to 2.29m2 g-1 (lowest peat, highest kerosene), while at 520nm wavelength MACBrC,OC,λ ranged from 0.07m2g-1 to 0.37m2 g-1 (lowest peat, highest kerosene/incensemixture). These MAC results show that OC content can be an important contributor to light absorption when present in significant quantities (>0.9 OC/TC), source emissions have variable absorption spectra, and nonbiomass combustion sources can be significant contributors to BrC.

DOI10.1002/2014JD022970
Short TitleJournal of Geophysical Research