Amines are likely to enhance neutral and ion-induced sulfuric acid-water nucleation in the atmosphere more effectively than ammonia

We have studied the structure and formation thermodynamics of dimer clusters containing H<sub>2</sub>SO<sub>4</sub> or HSO<sub>4</sub><sup>−</sup> together with ammonia and seven different amines possibly present in the atmosphere, using the high-level ab initio methods RI-MP2 and RI-CC2. As expected from e.g. proton affinity data, the binding of all studied amine-H<sub>2</sub>SO<sub>4</sub> complexes is significantly stronger than that of NH<sub>3</sub>•H<sub>2</sub>SO<sub>4</sub>, while most amine-HSO<sub>4</sub><sup>−</sup> complexes are only somewhat more strongly bound than NH<sub>3</sub>•HSO<sub>4</sub><sup>−</sup>. Further calculations on larger cluster structures containing dimethylamine or ammonia together with two H<sub>2</sub>SO<sub>4</sub> molecules or one H<sub>2</sub>SO<sub>4</sub> molecule and one HSO<sub>4</sub><sup>−</sup> ion demonstrate that amines, unlike ammonia, significantly assist the growth of not only neutral but also ionic clusters along the H<sub>2</sub>SO<sub>4</sub> co-ordinate. A sensitivity analysis indicates that the difference in complexation free energies for amine- and ammonia-containing clusters is large enough to overcome the mass-balance effect caused by the fact that the concentration of amines in the atmosphere is probably 2 or 3 orders of magnitude lower than that of ammonia. This implies that amines might be more important than ammonia in enhancing neutral and especially ion-induced sulfuric acid-water nucleation in the atmosphere

The role of ammonia in sulfuric acid ion induced nucleation

We have developed a new multi-step strategy for quantum chemical calculations on atmospherically relevant cluster structures that makes calculation for large clusters affordable with a good accuracy-to-computational effort ratio. We have applied this strategy to evaluate the relevance of ternary ion induced nucleation; we have also performed calculations for neutral ternary nucleation for comparison. The results for neutral ternary nucleation agree with previous results, and confirm the important role of ammonia in enhancing the growth of sulfuric acid clusters. On the other hand, we have found that ammonia does not enhance the growth of ionic sulfuric acid clusters. The results also confirm that ion-induced nucleation is a barrierless process at high altitudes, but at ground level there exists a barrier due to the presence of a local minimum on the free energy surface

Highly oxygenated organic molecule cluster decomposition in atmospheric pressure interface time-of-flight mass spectrometers

Identification of atmospheric molecular clusters and measurement of their concentrations by atmospheric pressure interface time-of-flight (APi-TOF) mass spectrometers may be affected by systematic error due to possible decomposition of clusters inside the instrument. Here, we perform numerical simulations of decomposition in an APi-TOF mass spectrometers and formation in the atmosphere of a set of clusters which involve a representative kind of highly oxygenated organic molecule (HOM), with the molecular formula C10H16O8. This elemental composition corresponds to one of the most common mass peaks observed in experiments on ozone-initiated autoxidation of alpha-pinene. Our results show that decomposition is highly unlikely for the considered clusters, provided their bonding energy is large enough to allow formation in the atmosphere in the first place.Peer reviewe

Communication: Tolman length and rigidity constants of water and their role in nucleation

A proper understanding of nucleation is crucial in several natural and industrial processes. However, accurate quantitative predictions of this phenomenon have not been possible. The most popular tool for calculating nucleation rates, classical nucleation theory (CNT), deviates by orders of magnitude from experiments for most substances. We investigate whether part of this discrepancy can be accounted for by the curvature-dependence of the surface tension. To that end, we evaluate the eading order corrections for water, the Tolman length and the rigidity constants, using square gradient theory coupled with the accurate cubic plus association equation of state. The Helfrich expansion is then used to incorporate them into the CNT-framework. For water condensation, the modified framework successfully corrects the erroneous temperature dependence of the nucleation rates given by the classical theory and reproduces experimental nucleation rates

Fatty acids on continental sulfate aerosol particles

Published 2005 American Geophysical Union. Reproduced by permission of American Geophysical Union.Surface analyses of atmospheric aerosols from different continental sources, such as forest fires and coal and straw burning, show that organic surfactants are found on such aerosols. The predominant organic species detected by time-of-flight secondary ion mass spectrometry on the sulfate aerosols are fatty acids of different carbon chain length up to the C32 acid. These observations are consistent with literature accounts of functional group analysis of bulk samples, but this is the first direct evidence of fatty acid films on the surface of sulfate aerosols. Surface analysis leads to the conclusion that fatty acid films on continental aerosols may be more common than has been previously suggested

Corrigendum to "The role of ammonia in sulfuric acid ion induced nucleation" published in Atmos. Chem. Phys., 8, 2859–2867, 2008

No abstract available

Composition and temporal behavior of ambient ions in the boreal forest

A recently developed atmospheric pressure interface mass spectrometer (APi-TOF) measured the negative and positive ambient ion composition at a boreal forest site. As observed in previous studies, the negative ions were dominated by strong organic and inorganic acids (e.g. malonic, nitric and sulfuric acid), whereas the positive ions consisted of strong bases (e.g. alkyl pyridines and quinolines). Several new ions and clusters of ions were identified based on their exact masses, made possible by the high resolution, mass accuracy and sensitivity of the APi-TOF. Time series correlograms aided in peak identification and assigning the atomic compositions to molecules. Quantum chemical calculations of proton affinities and cluster stabilities were also used to confirm the plausibility of the assignments. Acids in the gas phase are predominantly formed by oxidation in the gas phase, and thus the concentrations are expected to vary strongly between day and night. This was also the case in this study, where the negative ions showed strong diurnal behavior, whereas the daily changes in the positive ions were considerably smaller. A special focus in this work was the changes in the ion distributions occurring during new particle formation events. We found that sulfuric acid, together with its clusters, dominated the negative ion spectrum during these events. The monomer (HSO<sub>4</sub><sup>−</sup>) was the largest peak, together with the dimer (H<sub>2</sub>SO<sub>4</sub> · HSO<sub>4</sub><sup>−</sup>) and trimer ((H<sub>2</sub>SO<sub>4</sub>)<sub>2</sub> · HSO<sub>4</sub><sup>−</sup>). SO<sub>5</sub><sup>−</sup> also tracked HSO<sub>4</sub><sup>−</sup> at around 20% of the HSO<sub>4</sub><sup>−</sup> concentration at all times. During the strongest events, the tetramer and a cluster with the tetramer and ammonia were also detected. Quantum chemical calculations predict that sulfuric acid clusters containing ammonia are much more stable when neutral, thus the detection of a single ion cluster implies that ammonia can be an important compound in the nucleation process. We also believe to have made the first observations of an organosulfate (glycolic acid sulfate) in the gas phase. This ion, and its cluster with sulfuric acid, correlates with the HSO<sub>4</sub><sup>−</sup>, but peaks in the early afternoon, some hours later than HSO<sub>4</sub><sup>−</sup> itself. A list of all identified ions is presented in the supplementary material, and also a list of all detected masses not yet identified

LITHOSPHERE 2021: ELEVENTH SYMPOSIUM ON STRUCTURE, COMPOSITION AND EVOLUTION OF THE LITHOSPHERE: PROGRAMME AND EXTENDED ABSTRACTS

The Central Svecofennian Arc Complex (CSAC) and the Southern Svecofennian Arc Complex (SSAC) showdifferent ages of peak metamorphism: ~1.88 Ga in the CSAC and ~1.83 Ga in the SSAC. In the present project we study the age of the metamorphism in SW Finland. We have collected two samples. Of these the Eurajoki leucosome zircons were > 1.92 Ga, i.e.,inherited, but monazites show two populations: ~1.83 Ga and ~1.7 Ga. The zircons from the Rauma leucosome yielded two populations: ~1.86 Ga and ~1.83 Ga. The monazites show ages of ~1.83 Ga and ~1.7 Ga. We interpret that the ~1.86 Ga zircons represent the older metamorphism and the 1.83 Ga zircon and monazite group to represent the younger metamorphism. The 1.7 Ga group is unusual and needs further investigation.</p

The legacy of Finnish-Estonian air ion and aerosol workshops

Atmospheric air ions, clusters and aerosol particles participate in a variety of atmospheric processes and considerably affect e.g. global climate and human health. When measured, air ions as well as atmospheric clusters and particles have been observed to be present practically always and everywhere. In this overview, we present a brief summary of the main achievements and legacy of the series of workshops organized mainly by the University of Helsinki and the University of Tartu. The legacy covers the development and standardization of new instruments, such as ion spectrometers, mass spectrometers and aerosol particle counters, as well as work toward theoretical understanding of new-particle formation and evolution of atmospheric clusters. One important legacy is the establishment of the SMEAR-Estonia station at Jarvselja.Peer reviewe

Characterization and source identification of a fine particle episode in Finland

A strong long-range transported (LRT) fine particle (PM2.5) episode occurred from March 17–22, 2002 over large areas of Finland. Most of the LRT particle mass was in the submicrometre size fraction. The number of concentrations of 90–500 nm particles increased by a factor of 5.6 during the episode, but the concentrations of particles smaller than 90 nm decreased. This reduction of the smallest particles was caused by suppressed gas-to-particle conversion due to the vapour uptake of LRT particles. Individual particle analyses using SEM/EDX showed that the proportion of sulphur-rich particles rose strongly during the episode and that the relative weight percentage of potassium was unusually high in these particles. The median S/K ratios of S-rich particles were 2.1 at the beginning of the episode, 5.2 at the peak stage of the episode and 8.9 during the reference days. The high proportion of K is a clear indication of emissions from biomass burning, because K is a good tracer of biomass-burning aerosols. Trajectories and satellite detections of fire areas indicated that the main source of biomass-burning aerosols was large-scale agricultural field burning in the Baltic countries, Belarus, Ukraine and Russia. The higher S/K ratio of S-rich particles during the peak stage was obviously due to the increased proportion of fossil fuel-burning emissions in the LRT particle mass, since air masses arrived from the more polluted areas of Europe at that time. The concentrations of sulphate, total nitrate and total ammonium increased during the episode. Our results suggest that large-scale agricultural field burning may substantially affect PM2.5 concentrations under unfavourable meteorological conditions even at distances over 1000 km from the burning areas