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We examined the relationships linking atmospheric in-situ data of gas phase methane sulfonic acid (CH3SO3H, MSA), sulfuric acid (H2SO4, SA), iodic acid (HIO3), highly oxidized organic molecules (HOM) and aerosol particle concentrations in the size ranges of 10?50 nm and 100?450 nm with satellite-derived chlorophyll a (Chl-a) and oceanic primary production (PP) during two time spans – the phytoplankton early bloom period, April-May 2017 (30 March?1 June, springtime) and phytoplankton late bloom; June?July 2017 (2 June?4 August, summertime) – in two ocean domains; Greenland Sea and Barents Sea. Atmospheric data were collected at Ny-Ålesund site in Svalbard, Norway. In general, Chl-a and PP in the Barents Sea were higher than in the Greenland Sea during the April?May period, whereas the Greenland Sea had higher Chl-a and PP during June?July. Phytoplankton bloom started by the loss of sea ice coverage in the Barents Sea at the marginal ice zone (MIZ) during April?May, and in the Greenland Sea close to Svalbard Island during June?July. From the April?May period to the June?July period, the correlation between the ocean color data (Chl-a and PP) and MSA decreased in the Barents Sea and increased in the Greenland Sea, which establishes a direct relationship between the sea ice melting, phytoplankton bloom and atmospheric vapour composition. Both MSA and SA concentrations increased strongly during the bloom period, suggesting marine phytoplankton metabolism and resulting dimethyl sulphide (DMS) as the primary source of both MSA and SA in the Arctic atmosphere during spring–summer time. The highest correlation among all the atmospheric components and ocean color properties was observed between HIO3 and Chl-a in both ocean domains during the springtime, but this feature may be connected to processes associated with the melting of sea ice. HOMs showed a low correlation with Chl-a and PP in comparison to other atmospheric vapours. The plausible explanation for such low correlation is that the primary source of volatile organic compounds (VOC) – precursors of HOM – is the soil or terrestrial vegetation of Svalbard archipelago rather than the ocean. In springtime, small-particles (10-50 nm) correlated strongly with Chl-a in the Barents Sea and with PP in both oceanic domains, suggesting that biogenic productivity has a strong impact on new particle formation (NPF) in the springtime. In the summertime, small-particle concentrations showed almost no correlation with biogenic parameters, indicating that compounds not connected with phytoplankton metabolism, such as HOMs, have a critical role in summertime NPF. Larger particles (100?450 nm) showed an anti-correlation with Chl-a and PP in springtime, probably due to dilution of anthropogenic air pollution (arctic haze) during spring. In the end of the Arctic haze period in April, particle-phase SA (non-sea-salt sulphate, ?????? - ????42-) and particle phase MSA (MS-) showed almost no correlation, whereas a connection between the gas phase MSA and SA concentrations was found. The likely reason for this is the same origin for gas phase MSA and SA (DMS oxidation), whereas SA in particle phase mostly originated from a long-distance continental source. [ABSTRACT FROM AUTHOR]

At SMEAR II research station in Hyytiälä, located in the Finnish boreal forest, the process of new particle formation and the role of ions has been investigated for almost 20 years near the ground and at canopy level. However, above SMEAR II, the vertical distribution and diurnal variation of these different atmospheric ions are poorly characterized. In this study, we assess the atmospheric ion composition in the stable boundary layer, residual layer, mixing layer and free troposphere, and the evolution of these atmospheric ions due to photochemistry and turbulent mixing through the day. To measure the vertical profile of atmospheric ions, we developed a tailored setup for online mass spectrometric measurements, capable of being deployed in a Cessna 172 with minimal modifications. Simultaneously, instruments dedicated to aerosol properties measured in a second Cessna. We conducted a total of 16 measurement flights in May 2017, during the spring, which is the most active new particle formation season. A flight day typically consisted of three distinct flights through the day (dawn, morning and afternoon) to observe the diurnal variation and at different altitudes (from 100 m to 3200 m above ground), and to capture the boundary layer development from stable boundary layer, residual layer to mixing layer, and the free troposphere. Our observations showed that the ion composition is distinctly different in each layer and depends on the air mass origin and time of the day. Before sunrise, the layers are separated from each other and have their own ion chemistry. We observed that the ions present within the stable layer are of the same composition as the ions measured at the canopy level. During daytime when the mixing layer evolved and the compounds are vertically mixed, we observed that highly oxidised organic molecules are distributed to the top of the boundary layer. The ion composition in the residual layer varies with each day, showing similarities with either the stable boundary layer or the free troposphere. Finally, within the free troposphere, we detected a variety of carboxylic acids and ions that are likely containing halogens, originating from the Arctic Sea. [ABSTRACT FROM AUTHOR]

Several studies have investigated New Particle Formation (NPF) events from various sites ranging from pristine locations, including (boreal) forest sites to urban areas. However, there is still a dearth of studies investigating NPF processes and subsequent aerosol growth in coastal yet semi-urban sites, where the tropospheric layer is a concoction of biogenic and anthropogenic gases and particles. The investigation of factors leading to NPF becomes extremely complex due to the highly dynamic meteorological conditions at the coastline especially when combined with both continental and oceanic weather conditions. Herein, we engage a comprehensive study of particle number size distributions and aerosol-forming precursor vapors at the coastal semi-urban site in Helsinki, Finland. The measurement period, 25 June 2019-18 August 2019, was timed with the recurring cyanobacterial summer bloom in the Baltic Sea region and coastal regions of Finland. Our study recorded several regional/local NPF and aerosol burst events during this period. Although the overall anthropogenic influence on Sulfuric Acid (SA) concentrations was low during the measurement period, we observed that the regional or local NPF events, characterized by SA concentrations in the order of 107 molecules per cm-3 occurred mostly when the air mass travelled over the land areas. Interestingly, when the air mass travelled over the Baltic Sea, an area enriched with Algae and cyanobacterial blooms, high Iodic Acid (IA) concentration coincided with an aerosol burst or a spike event at the measurement site. Further, SA-rich bursts were seen when the air mass travelled over the Gulf of Bothnia, enriched with cyanobacterial blooms. The two most important factors affecting aerosol precursor vapor concentrations, and thus the aerosol formation, were (1) the type of phytoplankton species and intensity of bloom present in the coastal regions of Finland/ Baltic Sea and (2) the wind direction. During the events, most of the growth of sub-3 nm particles was probably due to SA, rather than IA or MSA, however much of the particle growth remained unexplained indicative of the strong role of organics in the growth of particles, especially in the 3-7 nm particle size range. Further studies are needed to explore the role of organics in NPF events and the potential influence of cyanobacterial blooms in coastal locations. [ABSTRACT FROM AUTHOR]

Sulfuric acid (H2SO4, SA) is the key compound in atmospheric new particle formation. Therefore, it is crucial to observe its concentration with sensitive instrumentation, such as chemical ionisation inlets coupled to Atmospheric Pressure interface Time-of-Flight mass spectrometers (CI-APi-TOF). However, there are environmental conditions and physical reasons when chemical ionisation cannot be used, for example in certain remote places or flight measurements with limitations regarding chemicals. In these cases, it is important to estimate the SA concentration based on ambient ion composition and concentration measurements that are achieved by APi-TOF alone. Here we derive a theoretical expression to estimate SA concentration and validate it with accurate CI-APi-TOF observations. The developed estimate works very well during daytime and with SA concentrations above 2⋅106 cm-3. [ABSTRACT FROM AUTHOR]

Iodic acid (HIO 3 ) is known to form aerosol particles in coastal marine regions, but predicted nucleation and growth rates are lacking. Using the CERN CLOUD (Cosmics Leaving Outdoor Droplets) chamber, we find that the nucleation rates of HIO 3 particles are rapid, even exceeding sulfuric acid-ammonia rates under similar conditions. We also find that ion-induced nucleation involves IO 3 - and the sequential addition of HIO 3 and that it proceeds at the kinetic limit below +10°C. In contrast, neutral nucleation involves the repeated sequential addition of iodous acid (HIO 2 ) followed by HIO 3 , showing that HIO 2 plays a key stabilizing role. Freshly formed particles are composed almost entirely of HIO 3 , which drives rapid particle growth at the kinetic limit. Our measurements indicate that iodine oxoacid particle formation can compete with sulfuric acid in pristine regions of the atmosphere., (Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)