Oxidative Properties of Atmospheric Particles and their Biological Effects.

Particulate Matter (PM) is the most toxic component in polluted air causing over 6 million deaths per year worldwide according to World Health Organisation estimates. Due to the highly complex composition of PM in the atmosphere, with thousands of inorganic and especially organic components, it is unknown which particle sources are responsible for their toxicity. In recent years it emerged that overall oxidising particle properties might directly link particle composition with health effects.

Black carbon and particle lung-deposited surface area in residential wood combustion emissions: Effects of an electrostatic precipitator and photochemical aging.

Residential wood combustion (RWC) remains a significant global source of particulate matter (PM) emissions with adverse impacts on regional air quality, climate, and human health. The lung-deposited surface area (LDSA) and equivalent black carbon (eBC) concentrations have emerged as important metrics to assess particulate pollution. In this study we estimated combustion phase-dependent emission factors of LDSA for alveolar, tracheobronchial, and head-airway regions of human lungs and explored the relationships between eBC and LDSA in fresh and photochemically aged RWC emissions.

Prolonged Dark Chemical Processes in Secondary Organic Aerosols on Filters and in Aqueous Solution.

Secondary organic aerosol (SOA) represents a large fraction of atmospheric aerosol particles that significantly affect both the Earth's climate and human health. Laboratory-generated SOA or ambient particles are routinely collected on filters for a detailed chemical analysis. Such filter sampling is prone to artifactual changes in composition during collection, storage, sample workup, and analysis.

Synthesis and Characterization of Organic Peroxides from Monoterpene-Derived Criegee Intermediates in Secondary Organic Aerosol.

Ozonolysis of alkenes is known to produce reactive intermediates─stabilized Criegee intermediates (SCIs), and their subsequent bimolecular reactions with various carboxylic acids can form α-acyloxyalkyl hydroperoxides (AAHPs), which is considered a major class of organic peroxides in secondary organic aerosol (SOA). Despite their atmospheric and health importance, the molecular-level identification of organic peroxides in atmospheric aerosols is highly challenging, preventing further assessment of their environmental fate. Here, we synthesize 20 atmospherically relevant AAHPs through liquid-phase ozonolysis, in which two types of monoterpene-derived SCIs from either α-pinene or 3-carene are scavenged by 10 different carboxylic acids to form AAHPs with diverse structures.

Iron and Copper Alter the Oxidative Potential of Secondary Organic Aerosol: Insights from Online Measurements and Model Development.

The oxidative potential (OP) of particulate matter has been widely suggested as a key metric for describing atmospheric particle toxicity. Secondary organic aerosol (SOA) and redox-active transition metals, such as iron and copper, are key drivers of particle OP. However, their relative contributions to OP, as well as the influence of metal-organic interactions and particulate chemistry on OP, remains uncertain.

A high-resolution monitoring approach of urban CO fluxes. Part 2 - surface flux optimisation using eddy covariance observations.

Achieving climate neutrality by 2050 requires ground-breaking technological and methodological advancements in climate change mitigation planning and actions from local to regional scales. Monitoring the cities' CO emissions with sufficient detail and accuracy is crucial for guiding sustainable urban transformation. Current methodologies for CO emission inventories rely on bottom-up (BU) approaches which do not usually offer information on the spatial or temporal variability of the emissions and present substantial uncertainties.

Dynamic Wood Smoke Aerosol Toxicity during Oxidative Atmospheric Aging.

Wildfires are a major source of biomass burning aerosol to the atmosphere, with their incidence and intensity expected to increase in a warmer future climate. However, the toxicity evolution of biomass burning organic aerosol (BBOA) during atmospheric aging remains poorly understood. In this study, we report a unique set of chemical and toxicological metrics of BBOA from pine wood smoldering during multiphase aging by gas-phase hydroxyl radicals (OH).

Cuticle chemistry drives the development of diffraction gratings on the surface of Hibiscus trionum petals.

Plants combine both chemical and structural means to appear colorful. We now have an extensive understanding of the metabolic pathways used by flowering plants to synthesize pigments, but the mechanisms remain obscure whereby cells produce microscopic structures sufficiently regular to interfere with light and create an optical effect. Here, we combine transgenic approaches in a novel model system, Hibiscus trionum, with chemical analyses of the cuticle, both in transgenic lines and in different species of Hibiscus, to investigate the formation of a semi-ordered diffraction grating on the petal surface.

A high-resolution monitoring approach of urban CO fluxes. Part 1 - bottom-up model development.

Monitoring carbon dioxide (CO) emissions of urban areas is increasingly important to assess the progress towards the Paris Agreement goals for climate neutrality. Cities are currently voluntarily developing their local inventories, however, the approaches used across different cities are not systematically assessed, present consistency issues, neglect the biogenic fluxes and have restricted spatial and temporal resolution. In order to assess the accuracy of the urban emission inventories and provide information which is useful for planning local climate change mitigation actions, high resolution modelling approaches combined or evaluated with atmospheric observations are needed.

Characterization and Quantification of Particle-Bound Criegee Intermediates in Secondary Organic Aerosol.

The ozonolysis of alkenes contributes substantially to the formation of secondary organic aerosol (SOA), which are important modulators of air quality and the Earth's climate. Criegee intermediates (CIs) are abundantly formed through this reaction. However, their contributions to aerosol particle chemistry remain highly uncertain.

Effect of Atmospheric Aging on Soot Particle Toxicity in Lung Cell Models at the Air-Liquid Interface: Differential Toxicological Impacts of Biogenic and Anthropogenic Secondary Organic Aerosols (SOAs).

Background: Secondary organic aerosols (SOAs) formed from anthropogenic or biogenic gaseous precursors in the atmosphere substantially contribute to the ambient fine particulate matter [PM in aerodynamic diameter ()] burden, which has been associated with adverse human health effects. However, there is only limited evidence on their differential toxicological impact.

Objectives: We aimed to discriminate toxicological effects of aerosols generated by atmospheric aging on combustion soot particles (SPs) of gaseous biogenic () or anthropogenic (naphthalene) precursors in two different lung cell models exposed at the air-liquid interface (ALI).

Atmospheric conditions and composition that influence PM oxidative potential in Beijing, China.

Epidemiological studies have consistently linked exposure to PM with adverse health effects. The oxidative potential (OP) of aerosol particles has been widely suggested as a measure of their potential toxicity. Several acellular chemical assays are now readily employed to measure OP; however, uncertainty remains regarding the atmospheric conditions and specific chemical components of PM that drive OP.

Ascorbate oxidation by iron, copper and reactive oxygen species: review, model development, and derivation of key rate constants.

Ascorbic acid is among the most abundant antioxidants in the lung, where it likely plays a key role in the mechanism by which particulate air pollution initiates a biological response. Because ascorbic acid is a highly redox active species, it engages in a far more complex web of reactions than a typical organic molecule, reacting with oxidants such as the hydroxyl radical as well as redox-active transition metals such as iron and copper. The literature provides a solid outline for this chemistry, but there are large disagreements about mechanisms, stoichiometries and reaction rates, particularly for the transition metal reactions.

Measurement of the fluorescence lifetime of GFP in high refractive index levitated droplets using FLIM.

Green fluorescent protein (GFP) is a widely used fluorescent probe in the life sciences and biosciences due to its high quantum yield and extinction coefficient, and its ability to bind to biological systems of interest. This study measures the fluorescence lifetime of GFP in sucrose/water solutions of known molarity in order to determine the refractive index dependent lifetime of GFP. A range of refractive indices from 1.

Comparison of Heated Electrospray Ionization and Nanoelectrospray Ionization Sources Coupled to Ultra-High-Resolution Mass Spectrometry for Analysis of Highly Complex Atmospheric Aerosol Samples.

Direct infusion analysis using soft ionization techniques coupled to ultra-high-resolution mass spectrometers (UHRMS) allows screening of thousands of organic species in complex samples. Despite the high analytical throughput of direct infusion, this technique is known to be prone to matrix effects caused by changes in the ionization efficiency of an analyte, ion suppression, or enhancement due to the presence of certain compounds and inorganic salts in the sample. In this study we compared two soft ionization sources, that is, heated electrospray ionization (HESI) and nano-ESI for the analysis of atmospheric aerosol samples in the negative ionization mode.

Organic Compounds in a Sub-Antarctic Ice Core: A Potential Suite of Sea Ice Markers.

Investigation of organic compounds in ice cores can potentially unlock a wealth of new information in these climate archives. We present results from the first ever ice core drilled on sub-Antarctic island Bouvet, representing a climatologically important but understudied region. We analyze a suite of novel and more familiar organic compounds in the ice core, alongside commonly measured ions.

Formation of metal-organic ligand complexes affects solubility of metals in airborne particles at an urban site in the Po valley.

Metals in atmospheric aerosols play potentially an important role in human health and ocean primary productivity. However, the lack of knowledge about solubility and speciation of metal ions in the particles or after solubilisation in aqueous media (sea or surface waters, cloud or rain droplets, biological fluids) limits our understanding of the underlying physico-chemical processes. In this work, a wide range of metals, their soluble fractions, and inorganic/organic compounds contained in urban particulate matter (PM) from Padua (Italy) were determined.

Radical Formation by Fine Particulate Matter Associated with Highly Oxygenated Molecules.

Highly oxygenated molecules (HOMs) play an important role in the formation and evolution of secondary organic aerosols (SOA). However, the abundance of HOMs in different environments and their relation to the oxidative potential of fine particulate matter (PM) are largely unknown. Here, we investigated the relative HOM abundance and radical yield of laboratory-generated SOA and fine PM in ambient air ranging from remote forest areas to highly polluted megacities.

Development of a Physiologically Relevant Online Chemical Assay To Quantify Aerosol Oxidative Potential.

Large-scale epidemiological studies have shown a close correlation between adverse human health effects and exposure to ambient particulate matter (PM). The oxidative potential (OP) of ambient PM has been implicated in inducing toxic effects associated with PM exposure. In particular, reactive oxygen species (ROS), either bound to PM or generated by particulate components in vivo, substantially contribute to the OP and therefore toxicity of PM by lowering antioxidant concentrations in the lung, which can subsequently lead to oxidative stress, inflammation, and disease.

Direct Depolymerization Coupled to Liquid Extraction Surface Analysis-High-Resolution Mass Spectrometry for the Characterization of the Surface of Plant Tissues.

The cuticle, the outermost layer covering the epidermis of most aerial organs of land plants, can have a heterogeneous composition even on the surface of the same organ. The main cuticle component is the polymer cutin which, depending on its chemical composition and structure, can have different biophysical properties. In this study, we introduce a new on-surface depolymerization method coupled to liquid extraction surface analysis (LESA) high-resolution mass spectrometry (HRMS) for a fast and spatially resolved chemical characterization of the cuticle of plant tissues.

Quantification of Particle-Bound Organic Radicals in Secondary Organic Aerosol.

The chemical composition and evolution of secondary organic aerosol (SOA) in the atmosphere represents one of the largest uncertainties in our current understanding of air quality. Despite vast research, the toxicological mechanisms relating to adverse human health effects upon exposure to particulate matter are still poorly understood. Particle-bound reactive oxygen species (ROS) may substantially contribute to observed health effects by influencing aerosol oxidative potential (OP).

Direct Injection Liquid Chromatography High-Resolution Mass Spectrometry for Determination of Primary and Secondary Terrestrial and Marine Biomarkers in Ice Cores.

Many atmospheric organic compounds are long-lived enough to be transported from their sources to polar regions and high mountain environments where they can be trapped in ice archives. While inorganic components in ice archives have been studied extensively to identify past climate changes, organic compounds have rarely been used to assess paleo-environmental changes, mainly due to the lack of suitable analytical methods. This study presents a new method of direct injection high performance liquid chromatography-mass spectrometry (HPLC-MS) analysis, without the need of preconcentrating the melted ice, for the determination of a series of novel biomarkers in ice core samples indicative of primary and secondary terrestrial and marine organic aerosol sources.