Title | Formation of nitro-PAHs from the heterogeneous reaction of ambient particle-bound PAHs with N2O5/NO3/NO2. |
Publication Type | Journal Article |
Year of Publication | 2013 |
Authors | Zimmermann, K, Jariyasopit, N, Simonich, SLMassey, Tao, S, Atkinson, R, Arey, J |
Journal | Environ Sci Technol |
Volume | 47 |
Issue | 15 |
Pagination | 8434-42 |
Date Published | 2013 Aug 6 |
ISSN | 1520-5851 |
Keywords | Adsorption, Nitrogen Oxides, Particulate Matter, Polycyclic Hydrocarbons, Aromatic, Surface Properties |
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. |
DOI | 10.1021/es401789x |
Alternate Journal | Environ. Sci. Technol. |
PubMed ID | 23865889 |
PubMed Central ID | PMC4167764 |
Grant List | P30 ES000210 / ES / NIEHS NIH HHS / United States P30ES00210 / ES / NIEHS NIH HHS / United States P42 ES016465 / ES / NIEHS NIH HHS / United States P42 ES016465 / ES / NIEHS NIH HHS / United States |