IEECAS OpenIR  > 黄土与第四纪地质国家重点实验室(2010~)
Improved estimation of PM2.5 brown carbon contributions to filter light attenuation
Chow, Judith C.1,2,3; Chen, L-W Antony1,4; Wang, Xiaoliang1,3; Green, Mark C.1,3; Watson, John G.1,2,3
Corresponding AuthorChow, Judith C.(
Source PublicationPARTICUOLOGY
AbstractMultiwavelength light attenuation measurements have been acquired as part of thermal/optical carbon analysis in the U.S. Chemical Speciation Network (CSN) and the Interagency Monitoring of PROtected Visual Environments (IMPROVE) network beginning in 2016. These are used to estimate PM2.5 brown carbon (BrC) contributions to light absorption at various wavelengths, a useful method for separating biomass burning contributions from other sources. Attenuation of light transmitted through the filter deviates from Beers Law as the mass of light absorbing materials increase. This study estimates the effects of these deviations with empirical adjustment factors applied to samples for CSN from 2016 to 2017 and for IMPROVE from 2016 to 2019. Accounting for the filter loading effect results in an annual average increase of similar to 6-7% BrC contribution to light attenuation: from 3.6% to 10.7% for the urban, more heavily loaded CSN samples; and from 23.7% to 29.5% for the non-urban IMPROVE samples. An alternative method is examined for BrC and black carbon (BC) adjustments by calculating the Absorption Angstrom Exponent (AAE) for BC (i.e., AAE(BC)) based on the ratios of 635 nm/780 nm light attenuation rather than assuming AAE(BC) of unity. These paired-wavelength calculations result in a median AAE(BC) of 0.76 for CSN and 0.8 for IMPROVE, with the majority of samples (i.e., 91% of CSN and 70% of IMPROVE) showing AAE(BC) < 1. By assuming negligible contributions from BrC to AAE at longer wavelengths, the amount of light attenuation at shorter wavelengths (e.g., 405 nm) where BrC is dominant can be calculated. The paired-wavelength method applied to the filter loading adjusted data has a greater effect on urban (fresh) than on non-urban (aged) aerosols, resulting in a factor of two increase in annual averaged BrC light attenuation (from 10.7% to 21.6%) for CSN and by a factor of 1.11 (from 29.5% to 32.7%) for IMPROVE samples. This result demonstrates the importance of particle loading and AAE correction on quantifying BrC light attenuation from multi-wavelength thermal/optical analysis. Published by Elsevier B.V. on behalf of Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences.
KeywordOrganic carbon Brown carbon Elemental carbon Black carbon Absorption Angstrom Exponent
Indexed BySCI ; SCI
Funding ProjectNational Park Service IMPROVE Carbon Analysis Contract[P16PC00229]
WOS Research AreaEngineering ; Materials Science
Funding OrganizationNational Park Service IMPROVE Carbon Analysis Contract
WOS SubjectEngineering, Chemical ; Materials Science, Multidisciplinary
WOS IDWOS:000637319400001
Citation statistics
Cited Times:8[WOS]   [WOS Record]     [Related Records in WOS]
Document Type期刊论文
Corresponding AuthorChow, Judith C.
Affiliation1.Desert Res Inst, Div Atmospher Sci, Reno, NV 89512 USA
2.Chinese Acad Sci, Inst Earth Environm, State Key Lab Loess & Quaternary Geol, Xian, Peoples R China
3.Univ Nevada, Grad Fac, Dept Atmospher Sci, Reno, NV 89557 USA
4.Univ Nevada, Sch Publ Hlth, Dept Environm & Occupat Hlth, Las Vegas, NV USA
Recommended Citation
GB/T 7714
Chow, Judith C.,Chen, L-W Antony,Wang, Xiaoliang,et al. Improved estimation of PM2.5 brown carbon contributions to filter light attenuation[J]. PARTICUOLOGY,2021,56:1-9.
APA Chow, Judith C.,Chen, L-W Antony,Wang, Xiaoliang,Green, Mark C.,&Watson, John G..(2021).Improved estimation of PM2.5 brown carbon contributions to filter light attenuation.PARTICUOLOGY,56,1-9.
MLA Chow, Judith C.,et al."Improved estimation of PM2.5 brown carbon contributions to filter light attenuation".PARTICUOLOGY 56(2021):1-9.
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