Barbara Zielinska

The formation of nitro-PAH from the gas-phase reactions of fluoranthene and pyrene with the OH radical in the presence of NOx

The products of the gas-phase reactions of the OH radical with fluoranthene and pyrene in the presence of NOx have been studied in a ~6400-l environmental chamber. 2-Nitropyrene was the sole nitro-PAH formed from pyrene, while 2-nitrofluoranthene, together with much smaller amounts of 7- and 8-nitrofluoranthene, were formed from fluoranthene. 2-Nitrofluoranthene and 2-nitropyrene have not been reported to be present in direct combustion-generated emissions nor to be formed during sampling of ambient particulate matter. It is estimated that this daytime OH radical-initiated formation route to 2-nitrofluoranthene, the major mononitro-PAH observed in ambient particulate matter, is comparable in importance to night-time formation via reaction of fluoranthene with N2O5.

Determination of 2-nitrofluoranthene and 2-nitropyrene in ambient particulate organic matter: Evidence for atmospheric reactions

Abstract We have identified and quantified 2-nitrofluoranthene (2-NO2-FL) and 2-nitropyrene (2-NO2-PY), both strong, direct mutagens in paniculate organic matter (POM) samples collected in polluted ambient air in southern California. Samples were collected during four consecutive 6-h periods on 18–19 September 1984, during which the ambient concentrations of gaseous co-pollutants were characterized by long pathlength spectroscopic techniques and conventional analyzers. Concentrations ranged up to 0.3 ng m−3 for 2-NO2-FL and 0.02 ng m−3 for 2-NO2-PY. The 2-nitro isomers of fluoranthene and pyrene have not been observed in direct emissions of POM (e.g. diesel exhaust and wood smoke). However, we recently observed these isomers from laboratory reactions involving N2O5 or OH radicals and the parent compounds. Thus the identification of 2-NO2-FL and 2-NO2-PY in ambient POM suggests that chemical transformations of fluoranthene and pyrene may take place in polluted atmospheres.

Polycyclic aromatic hydrocarbon and nitroarene concentrations in ambient air during a wintertime high-NOx episode in the Los Angeles basin

Abstract The ambient concentrations of polycyclic aromatic hydrocarbons (PAH) (including biphenyl) and nitroarenes were measured during a wintertime, high-NOx episode at a location in Southern California. Daytime and night-time ambient air samples were collected using Hi-vol filters, polyurethane foam (PUF) plugs and Tenax-GC solid adsorbent. 2-Nitrofluoranthene was the most abundant particle-associated nitroarene, but higher concentrations of 1- and 2-nitronaphthalene, methylnitronaphthalenes and 3-nitrobiphenyl were observed on the PUF plugs. Our data show that the ambient concentrations of the more volatile PAH and nitroarenes can be far greater than those of the less volatile species, and suggest that the most abundant nitroarenes in ambient air arise from atmospheric transformations of PAH emitted from combustion sources.

The nitroarenes of molecular weight 247 in ambient particulate samples collected in southern california

Abstract In addition to the dominant nitroarenes 2-nitrofluoranthene and 1- and 2-nitropyrene, the less abundant nitroarenes of molecular weight 247 in ambient particles collected during summer and winter pollutant episode conditions in southern California have been identified by gas chromatography/mass spectrometry. The approximate order of abundance of these nitroarenes was: 2-nitrofluoranthene > 1-nitropyrene ∼ 2-nitropyrene > 8-nitrofluoranthene ≳ 3-nitrofluoranthene > 7-nitrofluoranthene > a nitroacephenanthrylene ∼ 4-nitropyrene. The concentrations of 2-nitrofluoranthene, 1- and 2-nitropyrene and, in some cases, 3- and 8-nitrofluoranthene in 12 ambient samples are given. Significant differences in the distributions of these nitroarene isomers were observed among these samples and these are attributed to the varying importance of direct emission and atmospheric formation by reaction of the gaseous parent polycyclic aromatic hydrocarbon with N 2 O 5 and/or the OH radical (in the presence of NO x ). In particular, a very high (≳ 100) 2-nitrofluoranthene/2-nitropyrene concentration ratio appears to be indicative of nitroarene formation through night-time N 2 O 5 reaction.

A Possible formation pathway for the 2-nitrofluoranthene observed in ambient particulate organic matter

Abstract The reaction of N2O5 with gaseous fluoranthene has been shown to be a possible formation pathway for the 2-nitrofluoranthene observed in ambient particulate organic matter.

The gas-phase reaction of naphthalene with N2O5 to form nitronaphthalenes

Abstract While the formation of nitroarenes from the reaction of NO 2 , containing traces of HNO 3 , in air with polycyclic aromatic hydrocarbons (PAH) adsorbed on combustion generated particles is now well recognized, little is known about the gas-phase reactions of PAH. In this study, the gas-phase reactions in air of N 2 O 3 with part-per-million levels of naphthalene have been studied at room temperature and atmospheric pressure in a 5800V Teflon-coated environmental chamber. The kinetic data obtained showed that in these N 2 O 5 -NO 3 -NO 2 -air mixtures studied, naphthalene did not react with the NO 3 radical at an observable rate, but that it reacted with N 2 O 5 with a rate constant of ~ (2–3) × 10 −17 cm 3 molecule −1 s −1 . Significant yields of 1-nitronaphthalene and 2-nitronaphthalene ( ~ 18 and ~ 7.5%, respectively) were obtained from this reaction. The latter is a procarcinogen capable of being metabolized in animals to the carcinogen β-naphthylamine. These results and their atmospheric implications are discussed.

Factors influencing the reactivity of polycyclic aromatic hydrocarbons adsorbed on filters and ambient POM with ozone

Abstract Five polycyclic aromatic hydrocarbons (PAH), pyrene (PY), fluoranthene (FL), benz(a)anthracene (BaA), benzo(a)pyrene (BaP), and benzo(e)pyrene (BeP) adsorbed on glass fiber (GF) and Teflon impregnated glass fiber (TIGF) filters and on ambient particulate organic matter (POM) were exposed to ozone (50–300 ppb) passively in a 360-liter Teflon chamber and actively in a flow system. The influence of ozone concentration, exposure time and relative humidity (RH) on the degree of degradation of these PAH was established. The most reactive PAH both on filters and in ambient POM were PY, BaA and BaP. Up to 50–80% of these PAH degraded in 3-hr exposures to 200 ppb of ozone at ∼1% RH; in a flow system, most of the degradation occurred within the first 10 minutes of exposure. With the exception of BaP, the degradation of the PAH tested on GF and TIGF filters were much lower at 50% RH than at 1% RH, whether they were exposed to ozone in an active or passive mode. Interestingly, RH did not significantly affect the reactivity of PAH present in ambient POM passively exposed to ozone. Our results show that PAH are susceptible to ozone degradation under many typical atmospheric conditions.

Reactions of adsorbed pyrene and perylene with gaseous N2O5 under simulated atmospheric conditions

Abstract We report here results of studies concerning the reactions of two representative polycyclic aromatic hydrocarbons (PAH), pyrene and perylene, adsorbed on glass fiber filters, towards gaseous N 2 O 5 , NO 3 radicals, NO 2 and HNO 3 at part-per-million or lower concentrations and at ⩽ 5% relative humidity. These exposures were carried out in a passive mode in an ~ 6400-l all-Teflon environmental chamber. As is the case for naphthalene vapor, neither adsorbed pyrene nor perylene reacted to any observable extent with the NO 3 radical. However, pyrene reacted rapidly with N 2 O 3 to form 1-nitropyrene (1-NP) with a 60–70% yield after 50 min exposure to an initial N 2 O 5 concentration of 1.5 ppm. Under these conditions, no reaction of perylene with N 2 O 5 was observed. In control runs of the same duration, neither pyrene nor perylene reacted significantly ( 3 but, consistent with earlier studies, a ~ 3% yield of 3-nitroperylene (and NO 2 + 0.35 ppm HNO 3 . These data show for the first time that gas phase N 2 O 5 can be a strong nitrating agent for adsorbed pyrene to produce 1-nitropyrene, a powerful bacterial mutagen. Clearly, uncertainties occur in extrapolating our laboratory data to ambient atmospheres. However, when our results are combined with estimated N 2 O 5 concentrations of up to ~ 15 ppb in polluted night-time atmospheres, they suggest that nitro-PAH, could be formed at significant rates in ambient air.

Mutagenic activities of selected nitrofluoranthene derivatives in Salmonella typhimurium strains TA98, TA98NR and TA98/1,8-DNP6

The mutagenic activities of novel nitrofluoranthene derivatives in Salmonella strains TA98, TA98NR and TA98/1,8-DNP6 (with and without S9 addition) are given. These derivatives were produced from the reactions of fluoranthene (FL) and its directly mutagenic 2- and 3-nitro derivatives with covalent dinitrogen pentoxide (N2O5) in CCl4 solution at ambient temperature. The influence of the addition of a nitro group on the observed activity of the resulting di- and tri-nitrofluoranthenes is discussed.