Project Number: 19-031

Research

Title: Detecting events and seasonal trends in biomass burning plumes using black and brown carbon: (BC)2 El Paso

Institution(s) Represented: Baylor University - Rebecca Sheesley, University of Houston James Flynn

Lead PI: Rebecca Sheesley,

AQRP Project Manager: David Sullivan

TCEQ Project Liaison: Erik Gribbin

Awarded Amount: $131,294.00

Abstract

Recent efforts by Texas Air Quality Research Program (AQRP) and TCEQ to monitor and study air quality in Texas cities has resulted in improved understanding of the processes and sources which control urban air quality in e.g. Houston. As highlighted in the AQRP Priority Research Areas 2018-2019, El Paso is near the National Ambient Air Quality Standards for particulate matter (PM) and ozone (O3). Reductions in anthropogenic emissions through implementation of cleaner technologies for e.g. motor vehicle exhaust, coal-fired power plants, have refocused efforts to understand the contribution of biomass burning to urban air pollution. This is particularly relevant for El Paso, which can experience large impacts of periodic biomass burning/wildfire plumes transported from out-of-state. Black carbon (BC), a marker for combustion influences on air quality, has been shown to be decreasing in urban areas across the United States due to increased regulation and the use of cleaner fuels [2]. As a result, biomass burning contributions are likely becoming more important for BC and for urban air quality in general.

We will provide critical insight on the influence of biomass burning on the air quality in El Paso, TX through the characterization of BC and brown carbon (BrC). BrC is the carbon fraction of an aerosol that selectively absorbs short wavelengths of light. The (BC)2 El Paso field campaign will include the deployment of the Baylor air quality trailer, which will be outfitted with a suite of specific technologies developed to assess biomass burning through the monitoring of BC and BrC. Biomass burning plumes will be identified using aerosol composition and light absorption properties, including BC and BrC concentrations, absorption Ångström exponents (AAE), and aerosol light absorption coefficients for specific ultraviolet (UV) and visible wavelengths [3, 4]. The newest technology for real-time monitoring of aerosol absorption is the tricolor absorption photometer (TAP). The TAP measures adsorption at UV, green and red wavelengths to more specifically target biomass burning. This inexpensive and continuous photometer was designed by National Oceanic and Atmospheric Administration (NOAA) and is commercially produced by Brechtel to address issues with previous photometers, including cost, sensitivity, noise and effective scattering corrections [5]. Although it was only recently available, Baylor and UH PIs have run this instrument successfully during the 2017 San Antonio field campaign (SAFS) in the Baylor air quality trailer. The two goals of (BC)2 El Paso are to 1) address scientific air quality questions of frequency, seasonality, and optical properties of biomass burning plumes in El Paso and 2) to evaluate the TAP instrument suite for application in long-term monitoring at urban sites in Texas.

Hypothesis: Biomass burning is influencing air quality in El Paso, TX. The TAP instrument will provide a cost-effective, sensitive means of identifying biomass burning plumes in El Paso through the real-time characterization of black carbon and brown carbon.

To assess this hypothesis, a long-term field campaign, the Black Carbon, Brown Carbon El Paso or (BC)2 El Paso campaign, will be conducted deploying a suite of small footprint, low power, low maintenance, optical instruments in El Paso, TX (Fall 2018 to June 2019). This suite includes two, three wavelength TAPs, a three wavelength nephelometer, and a seven channel aethalometer. The dual goals of this deployment are to address scientific air quality questions of frequency, seasonality, and optical properties of biomass burning plumes in El Paso as well as the instrument evaluation of the TAP for application in long-term monitoring at urban sites in Texas. The science questions will utilize aerosol absorption measurements at two different wavelengths (e.g., UV and red wavelengths) to 1) identify biomass burning plumes and 2) use the range in observed absorption Ångström exponents (AAE) to characterize the biomass burning plumes. The results of this study could be used to develop effective strategies to improve air quality in El Paso. In addition, the instrument evaluation of the TAP will help TCEQ determine the suitability of this instrument for future deployment in Texas for characterization of biomass burning impacts.

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Research

Research

FY 2018 - 2019

Project Number: 19-031