The atmospheric chemistry of particulate-bound polycyclic aromatic hydrocarbons : concentration, prediction, laboratory studies, and mutagenicity

The trans-Pacific atmospheric transport of particulate matter (PM)-bound polycyclic aromatic hydrocarbons (PAHs) to remote sites in western North America has been well documented and has triggered research questions regarding to atmospheric transformation of PM-bound PAHs and the potential impacts on human health from their inhalation exposure. In this dissertation, field measurements, theoretical studies, laboratory experiments, and mutagenicity studies were used to begin the address the questions as to whether PM-bound PAHs undergo atmospheric transformation into mutagenic nitro-PAHs (NPAHs) during trans-Pacific atmospheric transport. PM extracts were tested in the Salmonella mutagenicity assay, using Salmonella typhimurium strain TA98 (with and without metabolic activation), to determine the mutagenic activities in relation to the chemical composition of the extracts. The sampling of atmospheric PM with diameter < 2.5 μm (PM₂.₅) before, during, and after the Olympic Games 2008 in Beijing provided some insights into the concentrations, chemical composition, photochemistry, and mutagenicity at the source of emission. The PAH, NPAH and OPAH composition of the PM₂.₅ was similar throughout the sampling periods, which included the period when a wide range of combustion sources were controlled. In addition, it showed that PAHs were associated with both local and regional emissions, while the NPAH and OPAH concentrations were only correlated with the NO concentrations, indicating that the NPAH and OPAH were primarily associated with local emissions. The characteristic NPAH ratios suggested a predominance of photochemical formation of NPAHs through OH radical-initiated reactions in the atmosphere. Subsequently, the heterogeneous reactions of PAHs bound to Beijing ambient PM with various oxidants, including NO₃/N₂O₅, OH radical and O₃, were studied using an environmental reaction chamber under simulated trans-Pacific transport conditions. In addition, PM collected from Riverside, CA was simultaneously exposed along with the Beijing PM in order to allow us to compare the reactivity between two different sites. In general, O₃ was most effective in degrading PM-bound PAHs with more than five rings, except for benzo[a]pyrene which was degraded by O₃ and NO₃/N₂O₅ equally well. However, the NPAHs were most effectively formed during the NO₃/N₂O₅ exposure. The reactivity of the PM could be explained by the degree to which the PM had been photochemically aged because the accumulation of degradation products on the surface of PM appeared to inhibit further atmospheric degradation of parent PAHs. For the NO₃/N₂O₅ exposure, the increase in direct-acting mutagenicity was associated with the formation of mutagenic NPAHs. Additional laboratory experiments were carried out in order to identify NPAH products of 5- to 6-ring PAHs through the heterogeneous reactions of surface-bound PAHs with NO₂, NO₃/N₂O₅, O₃, and OH radicals. Five PAHs, benzo[a]pyrene-d₁₂, benzo[k]fluoranthene-d₁₂, benzo[g,h,i]perylene-d₁₂, dibenzo(a,i)pyrene-d₁₄, and dibenzo[a,l]pyrene, were spiked onto quartz fiber filters and exposed in the chamber. Some of the identified NPAH products have not yet been measured in the environment. In parallel to the laboratory experiments, a theoretical study was conducted to assist in predicting the formation of NPAH isomers based on the gas-phase OH radical-initiated reaction. This study has shown that NO₂ and NO₃/N₂O₅ were effective oxidizing agents in transforming PAHs deposited on filters to NPAHs, under these experimental conditions. The lighter of the PAHs studied, including benzo[a]pyrene-d₁₂, benzo[k]fluoranthene-d₁₂ and benzo[ghi]perylene-d₁₂, yielded more than one mono-nitro isomer product, whereas dibenzo[a,l]pyrene and dibenzo[a,i]pyrene-d₁₄ resulted in the formation of only one mono-nitro isomer product. The direct-acting mutagenicity increased the most after NO₃/N₂O₅ exposure, particularly for benzo[k]fluoranthene-d₁₂ in which dinitro PAHs were observed

Heterogeneous reactions of particulate matter-bound PAHs and NPAHs with NO3/N2O5, OH radicals, and O3 under simulated long-range atmospheric transport conditions: reactivity and mutagenicity.

The heterogeneous reactions of ambient particulate matter (PM)-bound polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs (NPAHs) with NO3/N2O5, OH radicals, and O3 were studied in a laboratory photochemical chamber. Ambient PM2.5 and PM10 samples were collected from Beijing, China, and Riverside, California, and exposed under simulated atmospheric long-range transport conditions for O3 and OH and NO3 radicals. Changes in the masses of 23 PAHs and 20 NPAHs, as well as the direct and indirect-acting mutagenicity of the PM (determined using the Salmonella mutagenicity assay with TA98 strain), were measured prior to and after exposure to NO3/N2O5, OH radicals, and O3. In general, O3 exposure resulted in the highest relative degradation of PM-bound PAHs with more than four rings (benzo[a]pyrene was degraded equally well by O3 and NO3/N2O5). However, NPAHs were most effectively formed during the Beijing PM exposure to NO3/N2O5. In ambient air, 2-nitrofluoranthene (2-NF) is formed from the gas-phase NO3 radical- and OH radical-initiated reactions of fluoranthene, and 2-nitropyrene (2-NP) is formed from the gas-phase OH radical-initiated reaction of pyrene. There was no formation of 2-NF or 2-NP in any of the heterogeneous exposures, suggesting that gas-phase formation of NPAHs did not play an important role during chamber exposures. Exposure of Beijing PM to NO3/N2O5 resulted in an increase in direct-acting mutagenic activity which was associated with the formation of mutagenic NPAHs. No NPAH formation was observed in any of the exposures of the Riverside PM. This was likely due to the accumulation of atmospheric degradation products from gas-phase reactions of volatile species onto the surface of PM collected in Riverside prior to exposure in the chamber, thus decreasing the availability of PAHs for reaction

UPLC-ESI-MRM/MS for Absolute Quantification and MS/MS Structural Elucidation of Six Specialized Pyranonaphthoquinone Metabolites From Ventilago harmandiana

Pyranonaphthoquinones (PNQs) are important structural scaffolds found in numerous natural products. Research interest in these specialized metabolites lies in their natural occurrence and therapeutic activities. Nonetheless, research progress has thus far been hindered by the lack of analytical standards and analytical methods for both qualitative and quantitative analysis. We report here that various parts of Ventilago harmandiana are rich sources of PNQs. We developed an ultraperformance liquid chromatography-electrospray ionization multiple reaction monitoring/mass spectrometry method to quantitatively determine six PNQs from leaves, root, bark, wood, and heartwood. The addition of standards in combination with a stable isotope of salicylic acid-D-6 was used to overcome the matrix effect with average recovery of 82% +/- 1% (n = 15). The highest concentration of the total PNQs was found in the root (11,902 mu g/g dry weight), whereas the lowest concentration was found in the leaves (28 mu g/g dry weight). Except for the root, PNQ-332 was found to be the major compound in all parts of V. harmandiana, accounting for similar to 48% of the total PNQs quantified in this study. However, PNQ-318A was the most abundant PNQ in the root sample, accounting for 27% of the total PNQs. Finally, we provide novel MS/MS spectra of the PNQs at different collision induction energies: 10, 20, and 40 eV (POS and NEG). For structural elucidation purposes, we propose complete MS/MS fragmentation pathways of PNQs using MS/MS spectra at collision energies of 20 and 40 eV. The MS/MS spectra along with our discussion on structural elucidation of these PNQs should be very useful to the natural products community to further exploring PNQs in V. harmandiana and various other sources

Heterogeneous Reactions of PM-Bound PAHs and NPAHs with NO₃/N₂O₅, OH Radicals, and O₃ under Simulated Long-Range Atmospheric Transport Conditions: Reactivity and Mutagenicity

The heterogeneous reactions of ambient particulate matter (PM)-bound polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs (NPAHs) with NO₃/N₂O₅, OH radicals, and O₃ were studied in a laboratory photochemical chamber. Ambient PM[subscript 2.5] and PM₁₀ samples were collected from Beijing, China and Riverside, California, and exposed under simulated atmospheric long-range transport conditions for O₃ and OH and NO₃ radicals. Changes in the masses of 23 PAHs and 20 NPAHs, as well as the direct and indirect-acting mutagenicity of the PM (determined using the Salmonella mutagenicity assay with TA98 strain), were measured prior to and after exposure to NO₃/N₂O₅, OH radicals, and O₃. In general, O₃ exposure resulted in the highest relative degradation of PM-bound PAHs with more than four rings (benzo[a]pyrene was degraded equally well by O₃ and NO₃/N₂O₅). However, NPAHs were most effectively formed during the Beijing PM exposure to NO₃/N₂O₅. In ambient air 2-nitrofluoranthene (2-NF) is formed from gas-phase NO₃ radical- and OH radical-initiated reactions of fluoranthene, and 2-nitropyrene (2-NP) is formed from gas-phase OH radical-initiated reaction of pyrene. There was no formation of 2-NF or 2-NP in any of the heterogeneous exposures, suggesting that gas-phase formation of NPAHs did not play an important role during chamber exposures. Exposure of Beijing PM to NO₃/N₂O₅ resulted in an increase in direct-acting mutagenic activity which was associated with the formation of mutagenic NPAHs. No NPAH formation was observed in any of the exposures of the Riverside PM. This was likely due to the accumulation of atmospheric degradation products from gas phase reactions of volatile species onto the surface of PM collected in Riverside prior to exposure in the chamber, thus decreasing the availability of PAHs for reaction

GAPS-megacities: A new global platform for investigating persistent organic pollutants and chemicals of emerging concern in urban air

A pilot study was initiated in 2018 under the Global Atmospheric Passive Sampling (GAPS) Network named GAPS-Megacities. This study included 20 megacities/major cities across the globe with the goal of better understanding and comparing ambient air levels of persistent organic pollutants and other chemicals of emerging concern, to which humans residing in large cities are exposed. The first results from the initial period of sampling are reported for 19 cities for several classes of flame retardants (FRs) including organophosphate esters (OPEs), polybrominated diphenyl ethers (PBDEs), and halogenated flame retardants (HFRs) including new flame retardants (NFRs), tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCDD). The two cities, New York (USA) and London (UK) stood out with ∼3.5 to 30 times higher total FR concentrations as compared to other major cities, with total concentrations of OPEs of 15,100 and 14,100 pg/m3, respectively. Atmospheric concentrations of OPEs significantly dominated the FR profile at all sites, with total concentrations in air that were 2-5 orders of magnitude higher compared to other targeted chemical classes. A moderately strong and significant correlation (r = 0.625, p < 0.001) was observed for Gross Domestic Product index of the cities with total OPEs levels. Although large differences in FR levels were observed between some cities, when averaged across the five United Nations regions, the FR classes were more evenly distributed and varied by less than a factor of five. Results for Toronto, which is a "reference city" for this study, agreed well with a more in-depth investigation of the level of FRs over different seasons and across eight sites representing different urban source sectors (e.g. traffic, industrial, residential and background). Future sampling periods under this project will investigate trace metals and other contaminant classes, linkages to toxicology, non-targeted analysis, and eventually temporal trends. The study provides a unique urban platform for evaluating global exposome.Fil: Saini, Amandeep. Environment and Climate Change; CanadáFil: Harner, Tom. Environment and Climate Change; CanadáFil: Chinnadhurai, Sita. Environment and Climate Change; CanadáFil: Schuster, Jasmin K.. Environment and Climate Change; CanadáFil: Yates, Alan. Environment and Climate Change; CanadáFil: Sweetman, Andrew. Lancaster Environment Centre; Reino UnidoFil: Aristizabal Zuluaga, Beatriz H.. Universidad Nacional de Colombia; ColombiaFil: Jiménez, Begoña. Consejo Superior de Investigaciones Científicas; EspañaFil: Manzano, Carlos A.. Universidad de Chile; ChileFil: Gaga, Eftade O.. Eskisehir Technical University; TurquíaFil: Stevenson, Gavin. National Measurement Institute; AustraliaFil: Falandysz, Jerzy. Uniwersytet Gdanski; PoloniaFil: Ma, Jianmin. Peking University; ChinaFil: Miglioranza, Karina Silvia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Kannan, Kurunthachalam. Nyu Grossman School Of Medicine; Estados UnidosFil: Tominaga, Maria. Sao Paulo State Environmental Company; BrasilFil: Jariyasopit, Narumol. No especifíca;Fil: Rojas, Nestor Y.. Universidad Nacional de Colombia; ColombiaFil: Amador-Muñoz, Omar. Universidad Nacional Autónoma de México; MéxicoFil: Sinha, Ravindra. Patna University; IndiaFil: Alani, Rose. University of Lagos; NigeriaFil: Suresh, R.. No especifíca;Fil: Nishino, Takahiro. Tokyo Metropolitan Research Institute for Environmental Protection; JapónFil: Shoeib, Tamer. American University In Cairo; Egipt

GAPS-megacities: A new global platform for investigating persistent organic pollutants and chemicals of emerging concern in urban air

A pilot study was initiated in 2018 under the Global Atmospheric Passive Sampling (GAPS) Network named GAPS-Megacities. This study included 20 megacities/major cities across the globe with the goal of better understanding and comparing ambient air levels of persistent organic pollutants and other chemicals of emerging concern, to which humans residing in large cities are exposed. The first results from the initial period of sampling are reported for 19 cities for several classes of flame retardants (FRs) including organophosphate esters (OPEs), polybrominated diphenyl ethers (PBDEs), and halogenated flame retardants (HFRs) including new flame retardants (NFRs), tetrabromobisphenol A (TBBPA) and hexabromocyclododecane (HBCDD). The two cities, New York (USA) and London (UK) stood out with ∼3.5 to 30 times higher total FR concentrations as compared to other major cities, with total concentrations of OPEs of 15,100 and 14,100 pg/m, respectively. Atmospheric concentrations of OPEs significantly dominated the FR profile at all sites, with total concentrations in air that were 2–5 orders of magnitude higher compared to other targeted chemical classes. A moderately strong and significant correlation (r = 0.625, p < 0.001) was observed for Gross Domestic Product index of the cities with total OPEs levels. Although large differences in FR levels were observed between some cities, when averaged across the five United Nations regions, the FR classes were more evenly distributed and varied by less than a factor of five. Results for Toronto, which is a ‘reference city’ for this study, agreed well with a more in-depth investigation of the level of FRs over different seasons and across eight sites representing different urban source sectors (e.g. traffic, industrial, residential and background). Future sampling periods under this project will investigate trace metals and other contaminant classes, linkages to toxicology, non-targeted analysis, and eventually temporal trends. The study provides a unique urban platform for evaluating global exposome.A global study across 20 megacities/major cities reporting urban air concentrations of flame retardants and plasticizers.Authors thank the United Nations Environment Programme (UNEP) and the Chemicals Management Plan (CMP) for financial support. The worldwide implementation of the Global Monitoring Plan is made possible thanks to the generous contributions to the Stockholm Convention Voluntary Trust Fund from the Governments of Japan, Norway, Sweden, and through the European Commission’s Thematic Programme for Environment andSustainable Management of Natural Resources, including Energy (ENRTP). Further, the contribution of the projects to support POPs monitoring activities in regions, funded through the Global Environment Facility (GEF) and the Strategic Approach to International Chemicals Management (SAICM), is greatly acknowledged. Monitoring activities and data collection and analysis are implemented in the five UN regions in cooperation with strategic partners and through the involvement of Regional Organization Groups and Global Coordination Group. We also thank Yasuyuki Shibata and Yoshikatsu Takazawa (Tokyo, Japan); Juan Mu~noz-Arnanz (Madrid, Spain) and Dilek €Ozkan and Sinan Kızıltug (_Istanbul, Turkey) for their help and assistance in the sampling campaign

Novel Nitro-PAH Formation from Heterogeneous Reactions of PAHs with NO₂, NO₃/N₂O₅, and OH Radicals: Prediction, Laboratory Studies and Mutagenicity

The heterogeneous reactions of benzo[a]pyrene-d₁₂ (BaP-d₁₂), benzo[k]fluoranthene-d₁₂ (BkF-d₁₂), benzo[ghi]perylene-d₁₂ (BghiP-d₁₂), dibenzo[a,i]pyrene-d₁₄ (DaiP-d₁₄), and dibenzo[a,l]pyrene (DalP) with NO₂, NO₃/N₂O₅, and OH radicals were investigated at room temperature and atmospheric pressure in an indoor Teflon chamber and novel mono NO₂-DaiP, and mono NO₂-DalP products were identified. Quartz fiber filters (QFF) were used as a reaction surface and the filter extracts were analyzed by GC/MS for nitrated-PAHs (NPAHs) and tested in the Salmonella mutagenicity assay, using Salmonella typhimurium strain TA98 (with and without metabolic activation). In parallel to the laboratory experiments, a theoretical study was conducted to rationalize the formation of NPAH isomers based on the thermodynamic stability of OH-PAH intermediates, formed from OH-radical-initiated reactions. NO₂ and NO₃/N₂O₅ were effective oxidizing agents in transforming PAHs to NPAHs, with BaP-d₁₂ being the most readily nitrated. Reaction of BaP-d₁₂, BkF-d₁₂ and BghiP-d₁₂ with NO₂ and NO₃/N₂O₅ resulted in the formation of more than one mono-nitro isomer product, while the reaction of DaiP-d₁₄ and DalP resulted in the formation of only one mono-nitro isomer product. The direct-acting mutagenicity increased the most after NO₃/N₂O₅ exposure, particularly for BkF-d₁₂ in which di-NO₂-BkF-d₁₀ isomers were measured. The deuterium isotope effect study suggested that substitution of deuterium for hydrogen lowered both the direct and indirect acting mutagenicity of NPAHs and may result in an underestimation of the mutagenicity of the novel NPAHs identified in this study.This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by the American Chemical Society and can be found at: http://pubs.acs.org/journal/esthag