Thomas Ramdahl

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.

Occurrence of nitro-pah in the atmosphere in a rural area

By means of gas chromatography with nitrogen sensitive detection and negative ion chemical ionization mass spectrometric detection 7 mononitro-PAH, 9-nitroanthracene, x-nitro-4,5-methylene-phenanthrene, 3-nitrofluoranthene, 1- and 2-nitropyrene, 10-nitrobenz(a)anthracene and 6-nitrobenzo-(a)pyrene have been identied in samples of airborne particulate matter. Furthermore, 8-nitrofluoranthene has been tentatively identified. The amounts of mononitro-PAH are one to two orders of magnitude lower than the most common carcinogenic PAH, as e.g. benzo(a)pyrene. Filter effects have been studied, 9-nitroanthracene can be transformed during sampling at low atmospheric concentrations of NO2 and photochemical oxidants to 9,10-dinitroanthracene and 10-nitroanthrone.

Chemical and biological characterization of emissions from small residential stoves burning wood and charcoal

Abstract Emissions from a small residential wood stove and a newly developed residential stove burning charcoal have been characterized by chemical analysis and mutagenicity testing (Ames Salmonella test). For wood burning the samples were taken under normal and starved air conditions burning birch and spruce separately. The burning conditions in the stove seemed to influence the emissions to a larger extent than the type of wood. The emissions of aldehydes, benzene and polycyclic aromatic hydrocarbons from the charcoal-burning stove are lower by a factor of 25–1000 as compared to the wood stove. The mutagenicity of the emissions showed a similar trend.

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.

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.

Mutagenicity of polycyclic aromatic compounds (PAC) identified in source emissions and ambient air

Several polycyclic aromatic compounds (PAC) including nitrated and oxygenated derivatives of polycyclic aromatic hydrocarbons (PAH) were tested for mutagenic activity in the Salmonella/microsome assay. Among the compounds tested the isomer mix of nitro-1-hydroxypyrenes showed the highest direct mutagenic response in both the Salmonella strain TA98 and TA100 (1251 revertants/micrograms and 463 revertants/micrograms, respectively). The direct-acting mutagenicity of the nitro-1-hydroxypyrene isomer mix was dependent upon reduction of the nitro function as evidenced by the decrease in activity observed with the nitroreductase-deficient and arylhydroxylamine esterifying-deficient tester strains. The oxygenated derivatives of PAH containing aldehyde or keto groups showed weak or no mutagenic responses. In most cases addition of S9 was essential for any mutagenic activity and the strain TA100 was more sensitive than the strain TA98. Within this group, 7H-dibenzo[c,g]fluoren-7-one showed the highest mutagenic effect; 7 and 22 revertants/micrograms using the strains TA98 and TA100, respectively.

Nitration of polycyclic aromatic hydrocarbons adsorbed to different carriers in a fluidized bed reactor

Abstract The reactivity of selected polycyclic aromatic hydrocarbons (PAH) adsorbed to various surfaces has been studied. PAH were adsorbed to silica, alumina or charcoal particles and exposed to ambient concentrations of NO 2 in air in a fluidized bed reactor. The reaction products were analyzed by capillary gas chromatography and gas chromatograpy/mass spectrometry. The results show that silica is a more reactive surface than alumina. The charcoal used showed to be very adsorbtive and too little material was recovered for analyses. The reactivity of the PAH compounds studied decrease in the order perylene > benzo(a)pyrene > pyrene > chrysene > fluoranthene and phenanthrene. The relevance of these results to the assessment of the possible formation of nitro-PAH in the atmosphere is discussed.

Chemical and biological characterization of emissions from a cereal straw burning furnace

Emissions from a cereal straw through-burning furnace have been characterized by chemical analysis and the Ames Salmonella/microsome assay. The emissions of polycyclic aromatic hydrocarbons (PAH) were considerable, from 24 to 64 mg per kilo dry fuel. Most of the mutagenic activity was found in the extracts of the particles, while the condensate fractions and the XAD-2 extracts showed much lower mutagenic responses.

Characterization of polar compounds such as polycyclic aromatic ketones in air pollution including wood smoke

Abstract The moderately polar compounds from various combustion emissions including wood smoke have been isolated by high performance liquid chromatography on silica gel. The compounds were analyzed by gas chromatography mass spectrometry. The various polycyclic aromatic compound (PAC) classes were determined by their characteristic mass spectra. Special emphasis has been given to the polycyclic aromatic ketones (PAK), which often are as abundant in environmental samples as polycyclic aromatic hydrocarbons (PAH). A number of moderately polar PACs have been synthesized and tested for mutagenicity in the Ames Salmonella mutagenicity assay and some PAKs were shown to be mutagenic but weaker mutagens than the nitro-PAH.

Emissions of organic micropollutants from discontinuously operated municipal waste incinerators

Abstract The emission of particles and organic micropollutants (PAH, PCDD and PCDF) was measured from three intermittently operated municipal waste incinerators of medium size. The mutagenicity of the stack gas samples were measured as well. The results show a good agreement between the PAH emitted and the mutagenicity in the stack gases, but none of these parameters correlate with the PCDD/PCDF content.