Application of Single-Particle Mass Spectrometer to Obtain Chemical Signatures of Various Combustion Aerosols

A single-particle mass spectrometer (SPMS) with laser ionization was constructed to determine the chemical composition of single particles in real time. The technique was evaluated using various polystyrene latex particles with different sizes (125 nm, 300 nm, 700 nm, and 1000 nm); NaCl, KCl, MgCO3, CaCO3, and Al2O3 particles with different chemical compositions; an internal mixture of NaCl and KCl; and an internal mixture of NaCl, KCl, and MgCl2 with different mixing states. The results show that the SPMS can be useful for the determination of chemical characteristics and mixing states of single particles in real time. The SPMS was then applied to obtain the chemical signatures of various combustion aerosols (diesel engine exhaust, biomass burning (rice straw), coal burning, and cooking (pork)) based on their single-particle mass spectra. Elemental carbon (EC)-rich and EC-organic carbon (OC) particles were the predominant particle types identified in diesel engine exhaust, while K-rich and EC-OC-K particles were observed among rice straw burning emissions. Only one particle type (ash-rich particles) was detected among coal burning emissions. EC-rich and EC-OC particles were observed among pork burning particles. The single-particle mass spectra of the EC or OC types of particles differed among various combustion sources. The observed chemical signatures could be useful for rapidly identifying sources of atmospheric fine particles. In addition, the detected chemical signatures of the fine particles may be used to estimate their toxicity and to better understand their effects on human health.

Impact of Nanocomposite Combustion Aerosols on A549 Cells and a 3D Airway Model

The use of nanomaterials incorporated into plastic products is increasing steadily. By using nano-scaled filling materials, thermoplastics, such as polyethylene (PE), take advantage of the unique properties of nanomaterials (NM). The life cycle of these so-called nanocomposites (NC) usually ends with energetic recovery. However, the toxicity of these aerosols, which may consist of released NM as well as combustion-generated volatile compounds, is not fully understood. Within this study, model nanocomposites consisting of a PE matrix and nano-scaled filling material (TiO2, CuO, carbon nano tubes (CNT)) were produced and subsequently incinerated using a lab-scale model burner. The combustion-generated aerosols were characterized with regard to particle release as well as compound composition. Subsequently, A549 cells and a reconstituted 3D lung cell culture model (MucilAir™, Epithelix) were exposed for 4 h to the respective aerosols. This approach enabled the parallel application of a complete aerosol, an aerosol under conditions of enhanced particle deposition using high voltage, and a filtered aerosol resulting in the sole gaseous phase. After 20 h post-incubation, cytotoxicity, inflammatory response (IL-8), transcriptional toxicity profiling, and genotoxicity were determined. Only the exposure toward combustion aerosols originated from PE-based materials induced cytotoxicity, genotoxicity, and transcriptional alterations in both cell models. In contrast, an inflammatory response in A549 cells was more evident after exposure toward aerosols of nano-scaled filler combustion, whereas the thermal decomposition of PE-based materials revealed an impaired IL-8 secretion. MucilAir™ tissue showed a pronounced inflammatory response after exposure to either combustion aerosols, except for nanocomposite combustion. In conclusion, this study supports the present knowledge on the release of nanomaterials after incineration of nano-enabled thermoplastics. Since in the case of PE-based combustion aerosols no major differences were evident between exposure to the complete aerosol and to the gaseous phase, adverse cellular effects could be deduced to the volatile organic compounds that are generated during incomplete combustion of NC.

Solid-phase excitation-emission matrix spectroscopy for chemical analysis of combustion aerosols

Exposure to ultrafine combustion aerosols such as particulate matter (PM) from residential woodburning, forest fires, cigarette smoke, and traffic emission have been linked to adverse health outcomes. Excitation-emission matrix (EEM) spectroscopy presents a sensitive and cost-effective alternative for analysis of PM organic fraction. However, as with other analytical chemistry methods, the miniaturization is hindered by a solvent extraction step and a need for benchtop instrumentation. We present a methodology for collecting and in-situ analysis of airborne nanoparticles that eliminates labor-intensive sample preparation and miniaturizes the detection platform. Nanoparticles are electrostatically collected onto a transparent substrate coated with solid-phase (SP) solvent—polydimethylsiloxane (PDMS). The PM organic fraction is extracted into PDMS and analyzed in-situ, thus avoiding liquid-phase extraction. In the SP-EEM analysis, we evaluated external and internal excitation schemes. Internal excitation shows the lowest scattering interference but leads to signal masking from PDMS fluorescence for λ<250nm. The external excitation EEM spectra are dependent on the excitation light incident angle; ranges of 30–40° and 55–65° show the best results. SP-EEM spectra of woodsmoke and cigarette smoke samples are in good agreement with the EEM spectra of liquid-phase extracts. The SP-EEM technique can be used to develop wearable sensors for exposure assessments and environmental monitoring.

An Integrative Workflow to Prioritize Toxicity Initiation Events From Air-liquid-interface Exposure of Human Lung Cells to Combustion Aerosols: First Application to Emissions From a Heavy Fuel Oil or Diesel Fuel Operated Ship Engine

BackgroundAdvancement in the instrumentation techniques made it possible to identify the compositions and concentrations of various chemicals, such as organic compounds or metals in combustion aerosols. However, the prediction of combustion aerosol-induced toxicity end points in lung epithelium cells is difficult due to the large number of non-linear chemical-biological interactions. It is evident that some chemicals present in the combustion aerosols upregulate certain genes/ proteins while other chemicals downregulate them, making the prediction of toxicity of a mixture of chemicals a challenging task. Also, the presence of large numbers of feedback and feedforward regulatory loops makes the entire prediction process highly dynamic. MethodsHere we present an integrative workflow to construct and analyze combustion aerosol-type specific chemical-gene regulatory network. For this, we develop an algorithm to estimate the combined regulatory effect of chemicals present in the combustion aerosol on each of the genes/proteins in the network. Further we rank the nodes by combining various network topological and non-topological parameters using a multi-objective optimization function. The top ranked nodes were used to identify aerosol-type specific key regulators that contributes toward the understanding of adverse outcomes due to the exposure of combustion aerosols. ResultsThe integrative workflow is evaluated using transcriptomics analysis carried out on human bronchial epithelium cell line BEAS-2B exposed at the air liquid interface (ALI) to the combustion aerosols generated by ship engine running either on distillate Diesel Fuel (DF) or on Heavy Fuel Oil (HFO) along with chemometric analysis. Based on the prioritized chemicals, we prepared DF and HFO combustion aerosols-specific chemical-gene regulatory network. Our study reveals the large differences in the observed biological effects caused by operating the same ship engine on the different fuels.ConclusionThe presented workflow can be used to investigate key regulatory processes associated with the toxicity outcomes of mixture of chemicals and also for the hazard classification and assessment of various combustion aerosols.

Responses of ocean biogeochemistry to atmospheric supply of lithogenic and pyrogenic iron-containing aerosols

Atmospheric supply of iron (Fe) to the ocean has been suggested to regulate marine productivity in large parts of the world’s ocean. However, there are still large uncertainties regarding how the atmospheric inputs of dissolved Fe (DFe) influence the seawater DFe concentrations and thus net primary production (NPP). Here, we use an atmospheric chemistry model and two ocean biogeochemistry models with high (Model H) and low (Model L) sensitivities to atmospheric sources of DFe to explore the responses of ocean biogeochemistry to different types of atmospheric inputs of DFe: mineral dust and combustion aerosols. When both Fe content in mineral dust of 3.5% and Fe solubility of 2% are prescribed in sensitivity simulations, the ocean models overestimate DFe concentration in the surface ocean downwind from the North African and East Asian dust plumes. Considering different degrees of atmospheric Fe processing reduces the overestimates of DFe concentration in the North Atlantic and North Pacific. The two ocean biogeochemistry models show substantially different magnitudes of responses to the atmospheric input of DFe. The more detailed Model H shows a much higher sensitivity of NPP to the change in combustion aerosols than to mineral dust, regardless of relative inputs of the sedimentary sources. This finding suggests that pyrogenic Fe-containing aerosols are more important sources of atmospheric bioavailable Fe for marine productivity than would be expected from the small amount of DFe deposition, especially in the Pacific and Southern oceans.

Comparison of Mainstream Smoke Composition from CR20 Resin Filter and Empty-Cavity Filter Cigarettes by Headspace SPME Coupled with GC×GC TOFMS and Chemometric Analysis

SummaryA previously established method based on headspace solidphase microextraction (HS-SPME) and comprehensive two-dimensional gas chromatography (GC×GC) coupled to time-of-flight mass spectrometry (TOFMS) has been used to evaluate and compare the profiles of semi-volatile compounds present in mainstream tobacco smoke particulate matter trapped on glass fibre filters for two types of cigarettes differing only in filter design. In the first cigarette, the filter cavity contained approximately 60 mg of a weakly basic macroporous polystyrene resin cross-linked with divinyl benzene and with surface amine functionality (CR20), whereas in the second cigarette, it was empty.Relative quantitative analysis, chemical identification, and chemical grouping allowed the use of both parametric and non-parametric analyses to identify differences in the chemical composition of the smokes from these cigarettes. The analysis demonstrated that in addition to the selective partial removal of volatile carbonyls and HCN demonstrated previously, CR20 selectively, but incompletely removed 316 compounds from the particulate phase of cigarette smoke, mainly aryl and aromatic hydrocarbons as well as other more volatile species. In contrast, the relative proportion of amines, hydroxylated aromatic compounds and less volatile species was increased in the smoke from the cigarette containing CR20 in the filter.Our findings show that high resolution GC techniques combined with mass spectrometry and chemometric approaches are powerful tools for deconvoluting the complexity of combustion aerosols, as well as helping to identify changes in chemical composition resulting from modifications to cigarette designs. [Beitr. Tabakforsch. Int. 28 (2019) 231–249]