1
|
Zimmermann K, Jariyasopit N, Massey Simonich SL, Tao S, Atkinson R, Arey J. Formation of nitro-PAHs from the heterogeneous reaction of ambient particle-bound PAHs with N2O5/NO3/NO2. Environ Sci Technol 2013; 47:8434-42. [PMID: 23865889 PMCID: PMC4167764 DOI: 10.1021/es401789x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Reactions of ambient particles collected from four sites within the Los Angeles, CA air basin and Beijing, China with a mixture of N2O5, NO2, and NO3 radicals were studied in an environmental chamber at ambient pressure and temperature. Exposures in the chamber system resulted in the degradation of particle-bound PAHs and formation of molecular weight (mw) 247 nitropyrenes (NPYs) and nitrofluoranthenes (NFLs), mw 273 nitrotriphenylenes (NTPs), nitrobenz[a]anthracenes (NBaAs), nitrochrysene (NCHR), and mw 297 nitrobenzo[a]pyrene (NBaP). The distinct isomer distributions resulting from exposure of filter-adsorbed deuterated fluoranthene to N2O5/NO3/NO2 and that collected from the chamber gas-phase suggest that formation of NFLs in ambient particles did not occur by NO3 radical-initiated reaction but from reaction of N2O5, presumably subsequent to its surface adsorption. Accordingly, isomers known to result from gas-phase radical-initiated reactions of parent PAHs, such as 2-NFL and 2- and 4-NPY, were not enhanced from the exposure of ambient particulate matter to N2O5/NO3/NO2. The reactivity of ambient particles toward nitration by N2O5/NO3/NO2, defined by relative 1-NPY formation, varied significantly, with the relative amounts of freshly emitted particles versus aged particles (particles that had undergone atmospheric chemical processing) affecting the reactivity of particle-bound PAHs toward heterogeneous nitration. Analyses of unexposed ambient samples suggested that, in nighttime samples where NO3 radical-initiated chemistry had occurred, heterogeneous formation of 1-NPY on ambient particles may have contributed to the ambient 1-NPY concentrations at downwind receptor sites. These results, together with observations that 2-NFL is consistently the dominant particle-bound nitro-PAH measured in ambient atmospheres, suggest that for PAHs that exist in both the gas- and particle-phase, the heterogeneous formation of particle-bound nitro-PAHs is a minor formation route compared to gas-phase formation.
Collapse
Affiliation(s)
- Kathryn Zimmermann
- Air Pollution Research Center, University of California Riverside, California 92521, USA
- Environmental Toxicology Graduate Program, University of California, Riverside, California 92521, USA
| | - Narumol Jariyasopit
- Department of Chemistry, Oregon State University Corvallis, Oregon 97331, USA
| | - Staci L. Massey Simonich
- Department of Chemistry, Oregon State University Corvallis, Oregon 97331, USA
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, Oregon 97331, USA
| | - Shu Tao
- College of Urban and Environmental Science, Peking University Beijing, China 100871
| | - Roger Atkinson
- Air Pollution Research Center, University of California Riverside, California 92521, USA
- Environmental Toxicology Graduate Program, University of California, Riverside, California 92521, USA
- Department of Environmental Sciences, University of California, Riverside, California, United States
- Department of Chemistry, University of California, Riverside, California, United States
| | - Janet Arey
- Air Pollution Research Center, University of California Riverside, California 92521, USA
- Environmental Toxicology Graduate Program, University of California, Riverside, California 92521, USA
- Department of Environmental Sciences, University of California, Riverside, California, United States
| |
Collapse
|