Carbon, hydrogen, nitrogen and chlorine isotope fractionation during 3-chloroaniline transformation in aqueous environments by direct photolysis, TiO photocatalysis and hydrolysis.

This study investigates carbon, hydrogen, nitrogen and chlorine isotope fractionation during the transformation of 3-chloroaniline (3-CA) via direct photolysis, TiO photocatalytic degradation at neutral condition and hydrolysis at pH 3, pH 7 and pH 11. Direct photolysis and ∙OH reaction (UV/HO) showed similar inverse isotope fractionation (ε) for carbon (1.9 ± 0.

Methanesulfonic acid (MSA) and SO formation from the addition channel of atmospheric dimethyl sulfide oxidation.

The formation of methanesulfonic acid (MSA) from the dimethyl sulfide addition channel primarily proceeds the reaction of methylsulfonyloxy radicals (CHSO) with H-atom donors, other than HO radicals. In competition with it, thermal decomposition of CHSO results in SO generation. The MSA/SO ratio is driven by the temperature dependence of CHSO decomposition.

New particle formation from isoprene under upper-tropospheric conditions.

Aircraft observations have revealed ubiquitous new particle formation in the tropical upper troposphere over the Amazon and the Atlantic and Pacific oceans. Although the vapours involved remain unknown, recent satellite observations have revealed surprisingly high night-time isoprene mixing ratios of up to 1 part per billion by volume (ppbv) in the tropical upper troposphere. Here, in experiments performed with the CERN CLOUD (Cosmics Leaving Outdoor Droplets) chamber, we report new particle formation initiated by the reaction of hydroxyl radicals with isoprene at upper-tropospheric temperatures of -30 °C and -50 °C.

Isoprene nitrates drive new particle formation in Amazon's upper troposphere.

New particle formation (NPF) in the tropical upper troposphere is a globally important source of atmospheric aerosols. It is known to occur over the Amazon basin, but the nucleation mechanism and chemical precursors have yet to be identified. Here we present comprehensive in situ aircraft measurements showing that extremely low-volatile oxidation products of isoprene, particularly certain organonitrates, drive NPF in the Amazonian upper troposphere.

Source apportionment of ultrafine particles in urban Europe.

There is a body of evidence that ultrafine particles (UFP, those with diameters ≤ 100 nm) might have significant impacts on health. Accordingly, identifying sources of UFP is essential to develop abatement policies. This study focuses on urban Europe, and aims at identifying sources and quantifying their contributions to particle number size distribution (PNSD) using receptor modelling (Positive Matrix Factorization, PMF), and evaluating long-term trends of these source contributions using the non-parametric Theil-Sen's method.

Exhalation metabolomics: A new force in revealing the impact of ozone pollution on respiratory health.

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The potential of high temporal resolution automatic measurements of PM composition as an alternative to the filter-based manual method used in routine monitoring.

Under the EU Air Quality Directive (AQD) 2008/50/EC member states are required to undertake routine monitoring of PM composition at background stations. The AQD states for PM speciation this should include at least: nitrate , sulfate , chloride (Cl), ammonium (NH4), sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), elemental carbon (EC) and organic carbon (OC). Until 2017, it was the responsibility of each country to determine the methodology used to report the composition for the inorganic components of PM.

Carbon and hydrogen isotope fractionation of phthalates during photocatalysis reactions in aqueous solution containing Fe(III) complexes or iron minerals.

The hydrogen and carbon isotope fractionation factor (εH, εC) of dimethyl-, diethyl‑ and dibutyl phthalic acid ester during photosensitized degradation by artificial sunlight with Fe(III) ions and iron minerals (hematite, goethite and magnetite) in aqueous solution were examined by compound-specific isotope analysis (CSIA) in order to analyze the degradation mechanism. Hematite does not catalyze photosensitized degradation of phthalates. The correlation of H and C isotope fractionation (Λ = ΔδH/ΔδC) of phthalates with increasing chain length (dimethyl-; diethyl‑; and dibutyl-) were compared with values of the ∙OH radical model reaction with the aromatic ring as well as acidic and alkaline hydrolysis.

Aerosol particle number concentration, ultrafine particle number fraction, and new particle formation measurements near the international airports in Berlin, Germany - First results from the BEAR study.

Studies revealed airports as a prominent source of ultrafine particles (UFP), which can disperse downwind to residential areas, raising health concerns. To expand our understanding of how air traffic-related emissions influence total particle number concentration (PNC) in the airport's surrounding areas, we conduct long-term assessment of airborne particulate exposure before and after relocation of air traffic from "Otto Lilienthal" Airport (TXL) to Berlin Brandenburg Airport "Willy Brandt" (BER) in Berlin, Germany. Here, we provide insights into the spatial-temporal variability of PNC measured in 16 schools recruited for Berlin-Brandenburg Air Study (BEAR).

Evidence driven indoor air quality improvement: An innovative and interdisciplinary approach to improving indoor air quality.

Indoor air pollution is a recognized emerging threat, claiming millions of lives annually. People are constantly exposed to ambient and indoor air pollution. The latest research shows that people in developed countries spend up to 90% of their time indoors and almost 70% at home.

Repurposing weather modification for cloud research showcased by ice crystal growth.

The representation of cloud processes in models is one of the largest sources of uncertainty in weather forecast and climate projections. While laboratory settings offer controlled conditions for studying cloud processes, they cannot reproduce the full range of conditions and interactions present in natural cloud systems. To bridge this gap, here we leverage weather modification, specifically glaciogenic cloud seeding, to investigate ice growth rates within natural clouds.

Molecular characteristics of sea spray aerosols during aging with the participation of marine volatile organic compounds.

Sea spray aerosols (SSAs) are one of the largest natural sources of aerosols globally, known to affect the earth's radiation budget and to play a pivotal role in air quality and climate. The physical and chemical properties of organic components in SSA change during long-distance atmospheric transport over the ocean. To characterize the evolution of organic components during the aging process of SSA, in this study, we use a flow reactor to simulate the oxidation processes of SSA produced by authentic seawater via OH radicals (in the presence of organic gases evaporated from seawater) and to present the molecular signatures of the nascent and aged SSA.

The impact of ammonia on particle formation in the Asian Tropopause Aerosol Layer.

During summer, ammonia emissions in Southeast Asia influence air pollution and cloud formation. Convective transport by the South Asian monsoon carries these pollutant air masses into the upper troposphere and lower stratosphere (UTLS), where they accumulate under anticyclonic flow conditions. This air mass accumulation is thought to contribute to particle formation and the development of the Asian Tropopause Aerosol Layer (ATAL).

The challenge of identifying dust events in a highly polluted Eastern Mediterranean region.

Dust pollution largely impacts our environment, health and well-being. However, there is no agreement on how dust-contaminated days are identified to study exposures, as methods differ across disciplines. Different quantitative thresholds, which rely on ground measurements, are generally used to define these events.

Strong synergistic and antagonistic effects of quinones and metal ions in oxidative potential (OP) determination by ascorbic acid (AA) assays.

A key challenge in oxidative potential (OP) assays is to accurately assess the cumulative impact of redox-active aerosol species rather than only their individual effects. This study investigates the OP of single and combined mixtures of 1,2-naphthoquinone (1,2-NQ), 1,4-naphthoquinone (1,4-NQ), 9,10-phenanthrenequinone (9,10-PQ), 1,4-benzoquinone (1,4-BQ), Cu, Fe, Mn, and Zn in standard ascorbic acid (OP) and the synthetic respiratory tract lining fluid (OP) assays. In both OP and OP, binary mixtures showed additive and synergistic effects in the presence of 1,2-NQ.

Anthropogenic sources and liquid water drive secondary organic aerosol formation over the eastern Himalaya.

Atmospheric aerosols have a serious impact on altering the radiation balance of the vulnerable Himalayan atmosphere. Organic aerosol (OA), one of the least resolved aerosol fractions in the Himalayas, constrain our competence to assess their climate impacts on the region. Here we investigate water-soluble OA molecules in PM samples collected from March to May 2019 at Lachung (27.

Estimating black carbon levels using machine learning models in high-concentration regions.

Black carbon (BC) is emitted into the atmosphere during combustion processes, often in conjunction with emissions such as nitrogen oxides (NO) and ozone (O), which are also by-products of combustion. In highly polluted regions, combustion processes are one of the main sources of aerosols and particulate matter (PM) concentrations, which affect the radiative budget. Despite the high relevance of this air pollution metric, BC monitoring is quite expensive in terms of instrumentation and of maintenance and servicing.

Energetics of the OH radical H-abstraction reactions from simple aldehydes and their geminal diol forms.

Context: Carbonyl compounds, especially aldehydes, emitted to the atmosphere, may suffer hydration in aerosols or water droplets in clouds. At the same time, they can react with hydroxyl radicals which may add or abstract hydrogen atoms from these species. The interplay between hydration and hydrogen abstraction is studied using density functional and quantum composite theoretical methods, both in the gas phase and in simulated bulk water.

Road Traffic Emissions Lead to Much Enhanced New Particle Formation through Increased Growth Rates.

New particle formation (NPF) is a major source of atmospheric aerosol particles, including cloud condensation nuclei (CCN), by number globally. Previous research has highlighted that NPF is less frequent but more intense at roadsides compared to urban background. Here, we closely examine NPF at both background and roadside sites in urban Central Europe.

Photo-Oxidation of α-Pinene Oxidation Products in Atmospheric Waters - pH- and Temperature-Dependent Kinetic Studies.

The atmospheric α-pinene oxidation leads to three carboxylic acids: norpinonic acid (NPA), pinic acid (PA), and 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA). In this study, the OH radical kinetics in the aqueous phase of these carboxylic acids were investigated at different temperatures and pH values of solutions. Activation parameters and the corresponding atmospheric lifetimes of the acids in the troposphere were derived.

Cloud micro- and macrophysical properties from ground-based remote sensing during the MOSAiC drift experiment.

In the framework of the Multidisciplinary drifting Observatory for the Study of Arctic Climate Polarstern expedition, the Leibniz Institute for Tropospheric Research, Leipzig, Germany, operated the shipborne OCEANET-Atmosphere facility for cloud and aerosol observations throughout the whole year. OCEANET-Atmosphere comprises, amongst others, a multiwavelength Raman lidar, a microwave radiometer, and an optical disdrometer. A cloud radar was operated aboard Polarstern by the US Atmospheric Radiation Measurement program.

Gas-Phase Formation of Sulfurous Acid (HSO) in the Atmosphere.

Sulfurous acid (HSO) is known to be thermodynamically instable decomposing into SO and HO. All attempts to detect this elusive acid in solution failed up to now. Reported HSO formation from an experiment carried out in a mass spectrometer as well as results from theoretical calculations, however, indicated a possible kinetic stability in the gas phase.