A hierarchical clustering approach was employed to identify the macro-source of organic compounds detected in a year-long dataset of PM2.5 samples collected from two sites using a UHPLC-HESI-HRMS system. The comparison between the agricultural and urban sites revealed that organic aerosols could affect human health differently, even when the measured organic carbon concentrations are extremely similar.

The chemical composition of the atmosphere is changing rapidly due to increasing anthropogenic activities. Especially the upper troposphere and lower stratosphere (UTLS) are sensitive to changes in chemical composition. Here, we present two case studies from the TPEx aircraft campaign in Germany in June 2024, probing different regions of the UTLS. An analysis of the collected filter samples by high-resolution orbitrap mass spectrometry and a subsequent non-target analysis allows for the identification of yet unknown compounds. Our findings reveal unique stratospheric compounds such as organoposphates, suspecting anthropogenic influence in the upper atmospheric layers.

Ultrafine particles (UFP) are of great health concern due to their small size, high surface area and potential to deeply penetrate into the lung. Sampling and analysis of UFP are challenged due to their low mass. Herein, we present results from a field campaign in which UFP were collected for 24 h on quartz fiber filters and subsequently analyzed using sophisticated analytical techniques. We found high seasonal but also daily variations for the quantified PAHs as well as the classified compound classes including hopanes. Correlations to physico-chemical and weather data were approached and the potential impact of local sources evaluated.

This study investigates the formation of SOA from the oxidation of two monoterpenes, limonene and sabinene, in an atmospheric chamber. The research aims to expand knowledge of aerosol formation, particularly the chemical structure and prominence of molecular dimers in monoterpene oxidation. Non-targeted analysis revealed oxidation products varying with temperature caused by differences in physical properties. Dimer masses were detected for sabinene and structural identification was attempted, with a dimer of MW 338 showing similarities to an equivalent beta-pinene dimer. In future, dimer investigations will be performed on aerosol samples from Hyytiala, Finland, in particular, searching for cross-product dimers.

In tropical forests, organic aerosols dominate atmospheric particles, with both, secondary (SOA) and primary organic aerosols (POA) playing key roles. However, distinguishing molecular markers for SOA and POA remains challenging. The Amazon basin provides a unique environment to study these interactions under pristine and polluted conditions. This study presents a size-resolved molecular characterization of OA using high-resolution mass spectrometry. Aerosol samples were collected at the Amazon Tall Tower Observatory, analyzed for molecular markers, and evaluated for source contributions. The results reveal multimodal distributions, highlighting the need for further research to understand the roles of POA and SOA in aerosol formation.

Surfactants characterization is essential to understand their role on cloud formation and aerosol surface properties. A new analytical procedure was developed and applied to aerosol and cloud samples from different environments to quantify surfactants and measure their surface tension properties. The results highlight the ubiquity and high concentrations of surfactants in the atmosphere, especially anionic surfactants. The surface tension of aerosol and the partitioning of surfactants between the surface and bulk phases in particles were calculated using three models derived from the literature, and applied to the surface tension results. The potential implications for cloud formation will be discussed.