On-road traffic emissions of polycyclic aromatic hydrocarbons and their oxy- and nitro- derivative compounds measured in road tunnel environments

Abstract

Vehicular emissions are a key source of polycyclic aromatic compounds (PACs), including polycyclic aromatic hydrocarbons (PAHs) and their oxygenated (OPAH) and nitrated (NPAH) derivatives, in the urban environment. Road tunnels are a useful environment for the characterisation of on-road vehicular emissions, providing a realistic traffic fleet and a lack of direct sunlight, chemical reactivity and non-traffic sources. In the present investigation the concentrations of selected PAHs, OPAHs and NPAHs have been measured in the Parc des Princes Tunnel in Paris (PdPT, France), and at the Queensway Road Tunnel and an urban background site in Birmingham (QT, U.K). A higher proportion of semi-volatile (3-4 ring) PAH, OPAH and NPAH compounds are associated with the particulate phase compared with samples from the ambient environment. A large (~85%) decline in total PAH concentrations is observed between 1992 and 2012 measurements in QT. This is attributed primarily to the introduction of catalytic converters in the U.K as well as increasingly stringent EU vehicle emissions legislation. In contrast, NPAH concentrations measured in 2012 are similar to those measured in 1996. This observation, in addition to an increased proportion of (Phe+Flt+Pyr) in the observed PAH burden in the tunnel, is attributed to the increased number of diesel passenger vehicles in the U.K during this period. Except for OPAHs, comparable PAH and NPAH concentrations are observed in both investigated tunnels (QT and PdP). Significant differences are shown for specific substances between PAC chemical profiles in relation with the national traffic fleet differences (33% diesel passenger cars in U.K. vs 69% in France and up to 80% taking into account all vehicle categories). The dominating and sole contribution of 1-Nitropyrene observed in the PdPT NPAH profile strengthens the promising use of this compound as a diesel exhaust marker for PM source apportionment studies.

Speciation of organic fraction does matter for source apportionment. Part 1: A one-year campaign in Grenoble (France)

“…(1-NP), expected to be a marker of diesel emissions (Keyte et al, 2016), was associated with this factor. Despite several efforts, PMF was unable to increase the 1-NP contribution into this factor and it remained distributed in the biomass burning factor due its strong correlation with levoglucosan.…”

Recent analytical methods for atmospheric polycyclic aromatic hydrocarbons and their derivatives

“…More recently, a GC–MS/MS method for determining 37 PAHQs in atmospheric samples has been developed and the adopted reductive TMS derivatization achieved a considerable improvement in their sensitivity (Toriba et al, ) (Figure ). On the other hand, GC‐NICI‐MS provided a practical direct detection of PAHQs without the derivatization (Albinet, Leoz‐Garziandia, Budzinski, & Villenave, ; Albinet, Nalin, Tomaz, Beaumont, & Lestremau, ; Keyte, Albinet, & Harrison, ).…”

“…samples, even though almost all GC-MS methods need acetyl derivatization to improve the sensitivity. More recently, a GC-MS/MS method for determining 37 PAHQs in atmospheric samples has been developed and the adopted reductive TMS derivatization achieved a considerable improvement in their sensitivity (Figure 2).On the other hand, GC-NICI-MS provided a practical direct detection of PAHQs without the derivatization (Albinet, Leoz-Garziandia,Budzinski, & Villenave, 2006; Albinet, Nalin, Tomaz, Beaumont, & Lestremau, 2014;Keyte, Albinet, & Harrison, 2016).PAHQs are generated by incomplete combustion in the same manner as PAHs and are subsequently released to the atmosphere.PAHQs have been reported as a typical organic substance included in airborne PM and gas phases(Andreou & Rapsomanikis, 2009; Bandowe et al, 2014;Delgado-Saborit et al, 2013;Eiguren-Fernandez et al, 2008a;Wei et al, 2015;Wingfors, Hägglund, & Magnusson, 2011). Although diesel PM is considered as a specific candidate for the primary source of PAHQs(Cho et al, 2004;Jakober et al, 2007), secondary formation from reactions of PAHs with ozone and radical species in the atmosphere have also been reported(Eiguren-Fernandez et al, 2008b;Lee, Lane, & Kim, 2015;Wang, L. et al, 2007).…”

Fast oxidation processes from emission to ambient air introduction of aerosol emitted by residential log wood stoves

“…Therefore, no formation of benz[a]anthracene-7,12-dione could occur. Additionally, (Keyte et al, 2016) showed that this compound had a primary origin in ambient air. This result supports the argument that the formation of typical by-products from PAH oxidation, observed from E to CF, was major and not a consequence of sampling artefacts or analytical drift.…”