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Using radiocarbon to constrain black and organic carbon aerosol sources in Salt Lake City
Author(s) -
Mouteva Gergana O.,
Randerson James T.,
Fahrni Simon M.,
Bush Susan E.,
Ehleringer James R.,
Xu Xiaomei,
Santos Guaciara M.,
Kuprov Roman,
Schichtel Bret A.,
Czimczik Claudia I.
Publication year - 2017
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2017jd026519
Subject(s) - aerosol , environmental science , radiocarbon dating , environmental chemistry , particulates , biomass burning , carbon black , atmospheric sciences , fossil fuel , total organic carbon , sulfate , isotopes of carbon , combustion , biomass (ecology) , chemistry , geology , geography , meteorology , oceanography , natural rubber , organic chemistry , paleontology
Black carbon (BC) and organic carbon (OC) aerosols are important components of fine particulate matter (PM 2.5 ) in polluted urban environments. Quantifying the contribution of fossil fuel and biomass combustion to BC and OC concentrations is critical for developing and validating effective air quality control measures and climate change mitigation policy. We used radiocarbon ( 14 C) to measure fossil and contemporary biomass contributions to BC and OC at three locations in Salt Lake City, Utah, USA, during 2012–2014, including during winter inversion events. Aerosol filters were analyzed with the Swiss_4S thermal‐optical protocol to isolate BC. We measured fraction modern ( f M ) of BC and total carbon in PM 2.5 with accelerator mass spectrometry and derived the f M of OC using isotope mass balance. Combined with 14 C information of end‐member composition, our data set of 31 14 C aerosol measurements provided a baseline of the fossil and contemporary biomass components of carbonaceous aerosol. We show that fossil fuels were the dominant source of carbonaceous aerosol during winter, contributing 88% (80–98%) of BC and 58% (48–69%) of OC. While the concentration of both BC and OC increased during inversion events, the relative source contributions did not change. The sources of BC also did not vary throughout the year, while OC had a considerably higher contemporary biomass component in summer at 62% (49–76%) and was more variable. Our results suggest that in order to reduce PM 2.5 levels in Salt Lake City to meet national standards, a more stringent policy targeting mobile fossil fuel sources may be necessary.