Nitro polycyclic aromatic hydrocarbons in atmospheric particulate matter of Athens, Greece

Photolysis of Nitroaromatic Compounds under Sunlight: A Possible Daytime Photochemical Source of Nitrous Acid?

“…NPs concentrations of 0.2–52 and 0.08–768 ng·m –3 were detected in the gas and particle phases, − respectively. The concentration of NPAHs was found to be 0.01–2.22 ng·m –3 in aerosols. − Biomass burning and fossil fuel combustion contribute to primary sources of Ar-NO 2 in the atmosphere, , with Ar-NO 2 emission factors of 0.14–11.1 and 0.64–2.4 mg·kg –1 , respectively. , Ar-NO 2 can be also produced from the homogeneous and heterogeneous oxidation of parent aromatics. − The homogeneous reaction, occurring between benzene and NO 3 – /NO 2 – in the aqueous solution, can lead to the formation of nitrophenols through the hydroxylation and nitration. , Catechol was oxidized by OH and NO 3 radicals in the gas phase to generate a β -hydroxyphenoxy/ ο -semiquinone radical, which further reacted with NO 2 to form nitrocatechol . Acting as important contributors to the light absorption of brown carbon (BrC), Ar-NO 2 have potential impacts on the global radiative balance, climate, and photochemistry .…”

Transient IR Spectroscopic Observation of Singlet and Triplet States of 2-Nitrofluorene: Revisiting the Photophysics of Nitroaromatics

“…Nitrated polycyclic aromatic hydrocarbons (NPAHs) have been studied extensively as they generally are considered atmospheric pollutants 1,2 and pose certain health concerns. Many NPAHs have been shown to be carcinogenic and mutagenic 3−7 and 2-nitrofluorene is such a substance, which has been investigated for its carcinogenicity 3 and mutagenic properties.…”

“…Nitrated polycyclic aromatic hydrocarbons (NPAHs) have been studied extensively as they generally are considered atmospheric pollutants , and pose certain health concerns. Many NPAHs have been shown to be carcinogenic and mutagenic − and 2-nitrofluorene is such a substance, which has been investigated for its carcinogenicity and mutagenic properties. − Not only 2-NF but also its possible photodegradation products (for instance NO • and ArO • , among others) , have been shown to be harmful species. , However, the photodegradation of 2-NF is inefficient compared to, e.g., 9-nitroanthracene, − and the primary relaxation pathway of 2-NF does not appear to lead to photodegradation.…”

Effects of Humidity and [NO3]/[N2O5] Ratio on the Heterogeneous Reaction of Fluoranthene and Pyrene with N2O5/NO3/NO2

“…Considering that neither 2-NFL nor 2-NPY have been directly observed from combustion emissions, − most research has focused on the contribution of the atmospheric reactions of FL and PY with gas-phase oxidants (OH or NO 3 radicals in the presence of NO 2 ). Some studies have suggested that these two nitro-PAHs were formed exclusively via atmospheric gas-phase reactions of FL and PY. , The production of 2-NFL involves the gas-phase reaction between FL and either OH or NO 3 radicals in the presence of NO 2 , whereas the production of 2-NPY mainly involves the gas-phase reaction of PY initiated by OH radical. − The formation of both 2-NFL and 2-NPY in the gas phase is a multistep addition–elimination reaction initiated by OH or NO 3 radical species. This radical-initiated reaction is postulated to proceed by an initiated-addition of OH radical (present during the day time) or the NO 3 radical (present during evening and night time) to the position with the highest electron density (the 3-position in FL and 1-position in PY), followed by the ortho addition of NO 2 (2-position) and subsequent loss of H 2 O or HNO 3 . − By contrast, many reports have also focused on the heterogeneous reactions of FL and PY with N 2 O 5 /NO 3 /NO 2 , but only 1-, 3-, 7-, 8-NFL, and 1-NPY have been observed as the reaction products. ,,, The formation of these NPAHs via heterogeneous chemistry has been proposed to occur via an ionic electrophilic nitration by the nitronium ion (NO 2 + ) .…”