Grantee Research Project Results
2013 Progress Report: Development and Deployment of an Instrumentation Suite for Comprehensive Air Quality Characterization Including Aerosol ROS
EPA Grant Number: R834799C001Subproject: this is subproject number 001 , established and managed by the Center Director under grant R834799
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: The Southeastern Center for Air Pollution and Epidemiology: Multiscale Measurements and Modeling of Mixtures
Center Director: Tolbert, Paige
Title: Development and Deployment of an Instrumentation Suite for Comprehensive Air Quality Characterization Including Aerosol ROS
Investigators: Weber, Rodney J. , Sarnat, Stefanie Ebelt , Strickland, Matthew J , Nenes, Athanasios , Mulholland, James , Sarnat, Jeremy , Bergin, Michael
Institution: Georgia Institute of Technology , Emory University
Current Institution: Georgia Institute of Technology , Duke University , Emory University , University of Nevada - Reno
EPA Project Officer: Chung, Serena
Project Period: January 1, 2011 through December 31, 2016
Project Period Covered by this Report: August 1, 2012 through July 31,2013
RFA: Clean Air Research Centers (2009) RFA Text | Recipients Lists
Research Category: Human Health , Air
Objective:
To provide a chemically comprehensive data set on ambient particle composition at various sites relative to roadway emissions that will be used by other SCAPE Projects. As a part of this effort, our goal is to develop new instruments and analytical methods to quantify concentrations of particle-bound reactive oxygen species (ROS) and the ability of aerosols to catalyze the production of ROS through interactions with antioxidants. These techniques will be deployed during SCAPE to provide a data set for investigating ROS sources and atmospheric processing.
Progress Summary:
- Deployment of a particle-bound ROS system and publication of method and results: In the past year, the MC-DCFH instrument was deployed as part of a suite of instruments for Project 1 field sampling (discussed next). The data were analyzed and a paper describing the method and results was published (King et al., 2013).
- Project 1 Ambient Sampling Program: A main goal of Project 1 was to provide detailed aerosol chemical characterization over different seasons at paired sampling sites: a fixed site (JST) and a mobile site. Both sites included a suite of identical instrumentation. Table 1 summarizes the field deployments completed. Each paired study involved roughly one month of intensive sampling with both online and offline (filter) instrumentation. Periodically, the mobile site was stationed at the fixed site (JST/JST) for instrument intercomparisons. The data generated have gone through initial QC and are available to other SCAPE investigators through an FTP site.
- Development of an Automated ROS-DTT Assay Analytical System for High Volume & EPA CAPS Filter Extract Analysis: Two automated analytical systems capable of unattended operation were developed for quantifying ROS via the acellular dithiothreitol (DTT) assay. One system was designed for analysis of the more concentrated Project 1 high volume filter extracts and is capable of running 14 samples autonomously. The second system was developed and constructed for analysis of the lower concentration extracts from EPA (CAPS filters), as part of a collaboration with Bob Devlin, and can run eight filters autonomously. Each system requires roughly one hour per sample. These new instruments allow for the analysis of many more filters than what was previously possible manually.
- ROS-DTT Analysis of Project 1 Filters: In the past year, significant effort has focused on analysis of the high volume filters collected at the site. Table 1 identifies sites where DTT analysis has been completed. The automated system discussed in (3) allows for extensive analysis and we have used it to investigate the DTT activity of various chemical fractions of ambient aerosols. Our filter extraction and analysis procedure involves: i. Extraction in water with DTT analysis for water soluble DTT. ii. A portion of the water extract is passed through a C18 SPE column and the DTT activity of the pass-through fraction is determined (i.e., hydrophilic DTT). The difference between the water soluble DTT and hydrophilic DTT is the hydrophobic DTT activity (or HULIS DTT activity). iii. After the water extraction, the remaining portion of the filter is extracted in methanol to obtain the DTT activity of insoluble (primary) aerosol species. iv. Hydrophilic and hydrophobic DTT activity is determined for the methanol extract. Thus, for each high volume filter, four (4) DTT analyses are done. To date DTT activity on roughly 170 filters has been quantified. The data are now being combined with the other chemical data collected at these sites to analyze sources and processes contributing to the ROS activity of ambient PM2.5 particles.
- ROS-DTT analysis of EPA CAPS Filters: As part of a collaborative study with Bob Devlin, the automated DTT system was used to analyze CAPS filters from two studies. A similar analysis to what was described above (without hydrophilic/hydrophobic analysis on methanol extract) has been completed on roughly 50 EPA filters. The data have been delivered to Bob Devlin and data analysis is in progress.
Minor Areas of Work:
- ROS-DTT Analysis of Project 2 In-Vehicle Filters: ROS analysis with the DTT probe has also been completed on a number of Project 2 filters. Because these filters contain significantly less mass than the high volume or EPA CAPS filters, the DTT analysis has been done by hand. These data have been provided to Project 2.
- GC-MS Method Development and Filter Analysis: Organic Tracers, PAHs and Quinones: Methods have been developed for quantification of a group of PAHs and quinones, in addition to a suite of organic tracer species. Analysis of PAHs and quinones on filters is proceeding. Also, methods were explored for various solvent extractions of the hydrophobic components (e.g., HULIS) from the C18 column for both water and methanol samples. The extracts will be chemically characterized via GC-MS and DTT assay.
- Provided Samples for Cellular Assays: With the goal to compare acellular assays of ROS to cellular assays, filter samples were collected and extracted at appropriate concentrations for preliminary testing of a cyto-toxicity assay in collaboration with Project 2 PI, Jeremy Sarnat, and Investigator Michael Caudle, who is supported by non-sponsored Emory departmental funds.
Future Activities:
- Finish field measurements in the next few months, including deployments in St. Louis and at the RS site for the CCAR collaborative study.
- Finish DTT analysis on all Project 1 high volume filters and EPA CAPS filters.
- Develop a method for analysis of water soluble metals and use this system to analyze Project 1 high volume filters for soluble metals in water extracts and the hydrophilic/hydrophobic portions of water extracts. This method will use an online metals instrument (Xact) based on XRF detection borrowed from the U of Massachusetts, Amherst.
- Develop an acellular method sensitive to metals. Previous studies show ROS is primarily associated with organic species and redox-active metals. The DTT assay is mainly sensitive to organics, and the ascorbate depletion assay has been found to be most sensitive to metals. Thus, by employing these two methods we hope to establish a comprehensive method for quantifying the ROS activity of all components in ambient particles. The ascorbate assay data will also be compared to the soluble metals results.
- Continue collaborations with EPA (Bob Devlin) for analysis of additional CAPS and possibly to provide filter extracts for EPA ROS analysis with other probes. Preliminary results suggest that different DTT assay fractions appear to be associated with different groups of biological endpoints, and that the DTT assay was at least as predictive of biological changes as PM mass or particle number.
- Continue collaborations with Project 2 and Emory researchers in the development, and possibly analysis, of a selective group of Project 1 high volume filters using a cellular assay to provide contrast to the extensive acellular assays ROS data generated as part of this project.
- Further analyze filters for quinones for a correlation analysis with the DTT data. Also, develop methods for chemical speciation of various organic fractions isolated by the C18 SPE method.
- Data analysis and publication: More detailed papers are planned for the next year focusing on the DTT results.
Journal Articles on this Report : 4 Displayed | Download in RIS Format
| Other subproject views: | All 62 publications | 17 publications in selected types | All 17 journal articles |
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| Other center views: | All 338 publications | 139 publications in selected types | All 135 journal articles |
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King LE, Weber RJ. Development and testing of an online method to measure ambient fine particulate Reactive Oxygen Species (ROS) based on the 2’,7’-dichlorofluorescin (DCFH) assay. Atmospheric Measurement Techniques 2013;6(7):1647-1658. |
R834799 (2013) R834799 (2014) R834799 (2015) R834799 (2016) R834799 (Final) R834799C001 (2013) R834799C001 (2014) R834799C001 (2015) R834799C001 (Final) |
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Liu J, Bergin M, Guo H, King L, Kotra N, Edgerton E, Weber RJ. Size-resolved measurements of brown carbon in water and methanol extracts and estimates of their contribution to ambient fine-particle light absorption. Atmospheric Chemistry and Physics 2013;13(24):12389-12404. |
R834799 (2014) R834799 (2015) R834799 (2016) R834799 (Final) R834799C001 (2013) R834799C001 (2014) R834799C001 (2015) R834799C001 (Final) |
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Verma V, Rico-Martinez R, Kotra N, King L, Liu J, Snell TW, Weber RJ. Contribution of water-soluble and insoluble components and their hydrophobic/hydrophilic subfractions to the reactive oxygen species-generating potential of fine ambient aerosols. Environmental Science & Technology 2012;46(20):11384-11392. |
R834799 (2012) R834799 (2013) R834799 (2014) R834799 (2015) R834799 (2016) R834799 (Final) R834799C001 (2012) R834799C001 (2013) R834799C001 (2014) R834799C001 (2015) R834799C001 (Final) |
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Verma V, Rico-Martinez R, Kotra N, Rennolds C, Liu J, Snell TW, Weber RJ. Estimating the toxicity of ambient fine aerosols using freshwater rotifer Brachionus calyciflorus (Rotifera: Monogononta). Environmental Pollution 2013;182:379-384. |
R834799 (2014) R834799 (2015) R834799 (2016) R834799 (Final) R834799C001 (2013) R834799C001 (2014) R834799C001 (2015) R834799C001 (Final) |
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Supplemental Keywords:
reactive oxygen species, ROS, oxidative stress, oxidative potential, Scientific Discipline, Health, Health Risk Assessment, Risk Assessments, Environmental Monitoring, Biochemistry, children's health, particulate matter, ambient air monitoring, climate change, air pollution, airshed modeling, ambient particle health effects, human health riskRelevant Websites:
Southeastern Center for Air Pollution & Epidemiology - Emory/Georgia Tech EPA Clean Air Research Center ExitProgress and Final Reports:
Original AbstractMain Center Abstract and Reports:
R834799 The Southeastern Center for Air Pollution and Epidemiology: Multiscale Measurements and Modeling of Mixtures Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R834799C001 Development and Deployment of an Instrumentation Suite for Comprehensive Air Quality Characterization Including Aerosol ROS
R834799C002 Examining In-Vehicle Pollution and Oxidative Stress in a Cohort of Daily Commuters
R834799C003 Novel Estimates of Pollutant Mixtures and Pediatric Health in Two Birth Cohorts
R834799C004 A Multi-City Time-Series Study of Pollutant Mixtures and Acute Morbidity
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.