ALBERT

Description: Interaction of anthropogenic particles with radiation and clouds plays an important role on Arctic climate change. Mixing state of aerosols is a key parameter to influence aerosol-cloud and aerosol-radiation interaction. However, little is known on this parameter in the Arctic, preventing an accurate representation of this information in global models. Here we used transmission electron microscopy with energy-dispersive X-ray spectrometry (TEM/EDS), scanning TEM, scanning electron microscopy (SEM), nanoscale secondary ion mass spectrometry (NanoSIMS), and atomic forces microscopy (AFM) to determine the size and mixing properties of individual particles at 100 nm–10 μm, with a particular focus on sulfate and carbonaceous particles. We found that non-sea salt sulfate particles with size range at 100–2000 nm were commonly coated with organic matter (OM) in summer. 20 % of sulfate particles also had soot inclusions which only appeared in the organic coating. The OM coating is estimated to contribute to 63 % of the particle volume on average. Theoretical optical calculations from the Mie code suggest that absorption cross section of individual OM-coated particles significantly increased when assuming the OM coating as light-absorbing brown carbon (BrC). The microscopic observations suggest that OM modulates the mixing structure of fine Arctic sulfate particles, which may determine their hygroscopicity and optical properties.

Description: There are limited measurements of the chemical composition, abundance, and sources of black carbon (BC) containing particles in the high Arctic. To address this, we report 93 days of Soot Particle Aerosol Mass Spectrometer (SP-AMS) data collected in the high Arctic. The period spans from February 20th until May 23rd 2015 at Villum Research Station (VRS) in Northern Greenland (81°36' N). Particulate sulfate (SO42−) accounted for 66 % of the non-refractory PM1, which amounted to 2.3 µg m−3 as an average value observed during the campaign. The second most abundant species was organic matter (24 %), averaging 0.55 µg m3. Both organic aerosol (OA) and PM1, estimated from the sum of all collected species, showed a marked decrease throughout May in accordance with Arctic haze leveling off. The refractory black carbon (rBC) concentration averaged 0.1 µg m−3 over the entire campaign. Positive Matrix Factorization (PMF) of the OA mass spectra yielded three factors: (1) a Hydrocarbon-like Organic Aerosol (HOA) factor, which was dominated by primary aerosols and accounted for 12 % of OA mass; (2) an Arctic haze Organic Aerosol (AOA) factor, which accounted for 64 % of the OA and dominated until mid-April while being nearly absent from the end of May; and (3) a more oxygenated Marine Organic Aerosol (MOA) factor, which accounted for 22 % of OA. AOA correlated significantly with SO42−, suggesting the main part of that factor being secondary OA. The MOA emerged late at the end of March, where it increased with solar radiation and reduced sea ice extent, and dominated OA for the rest of the campaign until the end of May. Important differences are observed among the factors, including the highest O/C ratio (0.95) and S/C ratio (0.011) for MOA – the marine related factor. Our data supports current understanding of the Arctic summer aerosols, driven mainly by secondary aerosol formation, but with an important contribution from marine emissions. In view of a changing Arctic climate with changing sea-ice extent, biogenic processes, and corresponding source strengths, highly time-resolved data are urgently needed in order to elucidate the components dominating aerosol concentrations.

Description: Understanding aerosol size distributions is crucial to our ability to predict aerosol number concentrations. When of favourable size and composition, both long range transported particles as well as locally formed ones may serve as Cloud Condensation Nuclei (CCN); small changes may have a large impact on the low CCN concentrations currently characteristic of the Arctic environment. Here, we present a cluster analysis of particle size distributions (PSD, size range 8–500 nm) simultaneously collected from three high Arctic sites across Europe during a three year period (2013–2015). Two sites are located in the Svalbard archipelago: Zeppelin research station (474 m above ground), and the nearby Gruvebadet Observatory (about 2 km distance from Zepplelin, 67 m above ground). The third site (Villum Research Station – Station Nord, 30 m above ground) is 600 km to the west-northwest of Zeppelin, at the tip of north-eastern Greenland. An inter-site comparison exercise is carried out for the first time including the Gruvebadet site. K-means analysis provided eight specific aerosol categories, further combined into broad PSD with similar characteristics, namely: pristine low concentrations (12–14 %), new particle formation (16–32 %), Aitken (21–35 %) and accumulation (20–50 %). Confined for longer time periods by consolidated pack sea ice regions, the Greenland site shows PSD with lower ultrafine mode aerosol concentrations during summer, but higher accumulation mode aerosol concentrations during winter relative to the Svalbard sites. By association with chemical composition and Cloud Condensation Nuclei properties, further conclusions can be derived. Three distinct types of accumulation mode aerosol are observed during winter months, associated with sea spray (largest detectable sizes), Arctic haze (main mode at 150 nm) and aged accumulation mode (main mode at 220 nm) aerosols. In contrast, locally produced and most likely of marine biogenic origin particles exhibit size distributions dominated by the nucleation and Atiken mode aerosol during summer months. The obtained data and analysis set now the stage for future studies; including apportioning the relative contribution of primary and secondary aerosol formation processes to the aerosol size distribution in high Arctic, and elucidating anthropogenic aerosol dynamics, transport and removal processes across the Greenland sea. In a region of enormous importance for future climate on Earth, it is imperative to continue strengthening international scientific cooperation, in order to address important research questions on scales beyond singular station or measurement events.

Description: The Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) provides size resolved information on the chemical composition of single particles with high time resolution. Within SAPUSS (Solving Aerosol Problems by Using Synergistic Strategies), continuous ATOFMS measurements of ambient particles were made simultaneously at two urban locations: urban background (UB) site and road side (RS) site in the city of Barcelona (Spain) from 17th September to 18th October 2010. Two different instrumental configurations were used: ATOFMS (TSI 3800) with a converging nozzle inlet (high efficiency at about 800–2000 nm) at the UB site and ATOFMS (TSI 3800–100) with an aerodynamic lens inlet (high efficiency at about 300–700 nm) at the RS site. This is the first time, to our knowledge, that two ATOFMS instruments have been deployed in the same field study. The different instrument configurations had an impact on the observed particle types at the two sites. Nevertheless, ten particle types were detected at both locations, including local and regional elemental carbon (22.7–58.9 % of total particles), fresh and aged sea salt (1.0-14.6%), local and regional nitrate -containing aerosols (3–11.6 %), local lead-containing metallic particles (0.1–0.2 %) and transported Fe-nitrate particles (0.8–2.5 %). The ATOFMS at the UB also characterised four particle types: calcium-containing dust (0.9 %), Saharan dust (1.3 %), vanadium-containing particles (0.9 %) and vegetative debris (1.7 %). By contrast, the high statistical counts of fine particles detected at the RS allowed identification of eight particle types. Four of these contained amines of primary and secondary origin. Aminium salts were found related to coarse sulphate rich particle types, suggesting heterogeneous reaction mechanisms for their formation. The other four particle types mainly containing organic carbon were found spiking at different types of the day, showing a complex single particle mixing state relationship between organic carbon and nitrate. This ATOFMS study clearly shows that the composition of atmospheric fine particles in Barcelona, and likely other Mediterranean urban areas, is complex, with a wide range of local and regional sources combining with chemical processing to produce at least twenty-two different particle types exhibiting different temporal behaviour. The advantage of using two ATOFMS instruments is also demonstrated, with the nozzle-skimmer configuration enabling detection of coarse dust particles and the aerodynamic lens configuration allowing better identification of particles rich in organic carbon and amines.

Description: Antarctic sea surface microlayer (SML) and bulk water samples were collected during the PI-ICE campaign from January until March 2019 at the west coast of the Antarctic Peninsula. SML samples were collected using the glass plate technique, corresponding bulk (subsurface) samples were collected by submerging a plastic bottle below the sea surface. Following chemical parameters were determined: dissolved organic carbon (DOC), particulate organic carbon (POC), total chlorophyll-a, main inorganic ions (chloride, sulfate, sodium, etc.), dissolved free carbohydrates (DFCHO), dissolved combined carbohydrates (DCCHO) and particulate combined carbohydrates (PCCHO). DCCHO and DFCHO were measured from filtered (0.2 µm) seawater after a desalination using electro-dialysis and high-performance anion exchange chromatography coupled with pulsed amperometric detection (HPAEC-PAD). PCCHO were measured from filters (0.2 µm polycarbonate membrane). DFCHO, DCCHO and PCCHO were determined as the sum of individual monosaccharides (e.g. arabinose, glucose, galactose, glucosamine, galactosamine, muramic acid, galacturonic acid, etc.). More details about the analytical procedures can be found in the manuscript. These data were collected in order to improve the understanding of the sea-air transfer of carbohydrates in this pristine environment. A corresponding data set for size-resolved aerosol particles can be found under following doi number (doi:10.1594/PANGAEA.927565).