Browsing by Subject "AMMONIA"

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  • Kupiainen-Määttä, Oona (2016)
    Evaporation rates of small negatively charged sulfuric acid-ammonia clusters are determined by combining detailed cluster formation simulations with cluster distributions measured in the CLOUD experiment at CERN. The analysis is performed by varying the evaporation rates with Markov chain Monte Carlo (MCMC), running cluster formation simulations with each new set of evaporation rates and comparing the obtained cluster distributions to the measurements. In a second set of simulations, the fragmentation of clusters in the mass spectrometer due to energetic collisions is studied by treating also the fragmentation probabilities as unknown parameters and varying them with MCMC. This second set of simulations results in a better fit to the experimental data, suggesting that a large fraction of the observed HSO4- and HSO4-center dot H2SO4 signals may result from fragmentation of larger clusters, most importantly the HSO4-center dot(H2SO4)(2) trimer.
  • Marini, Selena; Santangeli, Olena; Saarelainen, Pirjo; Middleton, Benita; Chowdhury, Namrata; Skene, Debra J.; Costa, Rodolfo; Porkka-Heiskanen, Tarja; Montagnese, Sara (2017)
    Patients with liver cirrhosis can develop hyperammonemia and hepatic encephalopathy (HE), accompanied by pronounced daytime sleepiness. Previous studies with healthy volunteers show that experimental increase in blood ammonium levels increases sleepiness and slows the waking electroencephalogram. As ammonium increases adenosine levels invitro, and adenosine is a known regulator of sleep/wake homeostasis, we hypothesized that the sleepiness-inducing effect of ammonium is mediated by adenosine. Eight adult male Wistar rats were fed with an ammonium-enriched diet for 4 weeks; eight rats on standard diet served as controls. Each animal was implanted with electroencephalography/electromyography (EEG/EMG) electrodes and a microdialysis probe. Sleep EEG recording and cerebral microdialysis were carried out at baseline and after 6 h of sleep deprivation. Adenosine and metabolite levels were measured by high-performance liquid chromatography (HPLC) and targeted LC/MS metabolomics, respectively. Baseline adenosine and metabolite levels (12 of 16 amino acids, taurine, t4-hydroxy-proline, and acetylcarnitine) were lower in hyperammonemic animals, while putrescine was higher. After sleep deprivation, hyperammonemic animals exhibited a larger increase in adenosine levels, and a number of metabolites showed a different time-course in the two groups. In both groups the recovery period was characterized by a significant decrease in wakefulness/increase in NREM and REM sleep. However, while control animals exhibited a gradual compensatory effect, hyperammonemic animals showed a significantly shorter recovery phase. In conclusion, the adenosine/metabolite/EEG response to sleep deprivation was modulated by hyperammonemia, suggesting that ammonia affects homeostatic sleep regulation and its metabolic correlates.
  • Xie, Hong-Bin; Elm, Jonas; Halonen, Roope; Myllys, Nanna; Kurten, Theo; Kulmala, Markku; Vehkamäki, Hanna (2017)
    Monoethanolamine (MEA), a potential atmospheric pollutant from the capture unit of a leading CO2 capture technology, could be removed by participating H2SO4-based new particle formation (NPF) as simple amines. Here we evaluated the enhancing potential of MEA on H2SO4-based NPF by examining the formation of molecular clusters of MEA and H2SO4 using combined quantum chemistry calculations and kinetics modeling. The results indicate that MEA at the parts per trillion (ppt) level can enhance H2SO4-based NPF. The enhancing potential of MEA is less than that of dimethylamine (DMA), one of the strongest enhancing agents, and much greater than methylamine (MA), in contrast to the order suggested solely by their basicity (MEA <MA <DMA). The unexpectedly high enhancing potential is attributed to the role of -OH of MEA in increasing cluster binding free energies by acting as both a hydrogen bond donor and acceptor. After the initial formation of one H2SO4 and one MEA cluster, the cluster growth mainly proceeds by first adding one H2SO4, and then one MEA, which differs from growth pathways in H2SO4-DMA and H2SO4-MA systems. Importantly, the effective removal rate of MEA due to participation in NPF is comparable to that of oxidation by hydroxyl radicals at 278.15 K, indicating NPF as an important sink for MEA.
  • Yao, Lei; Garmash, Olga; Bianchi, Federico; Zheng, Jun; Yan, Chao; Kontkanen, Jenni; Junninen, Heikki; Mazon, Stephany Buenrostro; Ehn, Mikael; Paasonen, Pauli; Sipilä, Mikko; Wang, Mingyi; Wang, Xinke; Xiao, Shan; Chen, Hangfei; Lu, Yiqun; Zhang, Bowen; Wang, Dongfang; Fu, Qingyan; Geng, Fuhai; Li, Li; Wang, Hongli; Qiao, Liping; Yang, Xin; Chen, Jianmin; Kerminen, Veli-Matti; Petäjä, Tuukka; Worsnop, Douglas R.; Kulmala, Markku; Wang, Lin (2018)
    Atmospheric new particle formation (NPF) is an important global phenomenon that is nevertheless sensitive to ambient conditions. According to both observation and theoretical arguments, NPF usually requires a relatively high sulfuric acid (H2SO4) concentration to promote the formation of new particles and a low preexisting aerosol loading to minimize the sink of new particles. We investigated NPF in Shanghai and were able to observe both precursor vapors (H2SO4) and initial clusters at a molecular level in a megacity. High NPF rates were observed to coincide with several familiar markers suggestive of H2SO4-dimethylamine (DMA)water (H2O) nucleation, including sulfuric acid dimers and H2SO4-DMA clusters. In a cluster kinetics simulation, the observed concentration of sulfuric acid was high enough to explain the particle growth to similar to 3 nanometers under the very high condensation sink, whereas the subsequent higher growth rate beyond this size is believed to result fromthe added contribution of condensing organic species. These findings will help in understanding urban NPF and its air quality and climate effects, as well as in formulating policies to mitigate secondary particle formation in China.
  • Similä, Minna E.; Auranen, Mari; Piirilä, Päivi Liisa (2020)
    Background: A deficiency of muscle phosphofructokinase (PFKM) causes a rare metabolic muscle disease, the Tarui disease (Glycogen storage disease type VII, GSD VII) characterized by exercise intolerance with myalgia due to an inability to use glucose as an energy resource. No medical treatment for GSD VII currently exists. The aim of this study was to determine whether a dietary intervention with excessive fat intake would benefit GSD VII.Patient and Methods: A ketogenic diet (KD) intervention implemented as a modified Atkins diet was established for one patient with PFKM deficiency, with a low late lactate response and very high ammonia levels associated with exercise. We recorded the KD intervention for a total of 5 years with clinical and physiotherapeutic evaluations and regular laboratory parameters. Cardiopulmonary exercise testing, including breath gas analysis and venous lactate and ammonia measurements, was performed before KD and at 3, 8 months and 5 years after initiation of KD.Results: During the 5 years on KD, the patient's muscle symptoms had alleviated and exercise tolerance had improved. In exercise testing, venous ammonia had normalized, the lactate profile remained similar, but oxygen uptake and mechanical efficiency had increased and parameters showing ventilation had improved.Conclusions: This study is the first to show a long-term effect of KD in GSD VII with an alleviation of muscle symptoms, beneficial effects on breathing, and improvement in exercise performance and oxygen uptake. Based on these findings, KD can be recommended under medical and nutritional supervision for selected patients with GSD VII, although further research of this rare disease is warranted.
  • Sipilä, M.; Sarnela, N.; Jokinen, T.; Junninen, H.; Hakala, J.; Rissanen, M. P.; Praplan, A.; Simon, M.; Kürten, A.; Bianchi, F.; Dommen, J.; Curtius, J.; Petäjä, T.; Worsnop, D.R. (2015)
    Atmospheric amines may play a crucial role in formation of new aerosol particles via nucleation with sulfuric acid. Recent studies have revealed that concentrations below 1 pptV can significantly promote nucleation of sulfuric acid particles. While sulfuric acid detection is relatively straightforward, no amine measurements to date have been able to reach the critical sub-pptV concentration range and atmospheric amine concentrations are in general poorly characterized. In this work we present a proof-of-concept of an instrument capable of detecting dimethyl amine (DMA) with concentrations even down to 70 ppqV (parts per quadrillion, 0.07 pptV) for a 15 min integration time. Detection of ammonia and amines other than dimethyl amine is discussed. We also report results from the first ambient measurements performed in spring 2013 at a boreal forest site. While minute signals above the signal-to-noise ratio that could be attributed to trimethyl or propyl amine were observed, DMA concentration never exceeded the detection threshold of ambient measurements (150 ppqV), thereby questioning, though not excluding, the role of DMA in nucleation at this location.
  • Simon, Mario; Heinritzi, Martin; Herzog, Stephan; Leiminger, Markus; Bianchi, Federico; Praplan, Arnaud; Dommen, Josef; Curtius, Joachim; Kuerten, Andreas (2016)
    Amines are potentially important for atmospheric new particle formation, but their concentrations are usually low with typical mixing ratios in the pptv range or even smaller. Therefore, the demand for highly sensitive gas-phase amine measurements has emerged in the last several years. Nitrate chemical ionization mass spectrometry (CIMS) is routinely used for the measurement of gas-phase sulfuric acid in the sub-pptv range. Furthermore, extremely low volatile organic compounds (ELVOCs) can be detected with a nitrate CIMS. In this study we demonstrate that a nitrate CIMS can also be used for the sensitive measurement of dimethylamine (DMA, (CH3)(2)NH) using the NO3-center dot(HNO3)(1-2)center dot(DMA) cluster ion signal. Calibration measurements were made at the CLOUD chamber during two different measurement campaigns. Good linearity between 0 and similar to 120 pptv of DMA as well as a sub-pptv detection limit of 0.7 pptv for a 10 min integration time are demonstrated at 278 K and 38% RH.
  • Elm, Jonas; Passananti, Monica; Kurten, Theo; Vehkamäki, Hanna (2017)
    Recent experimental evidence suggests that diamines can enhance atmospheric new particle formation more efficiently compared to monoamines such as dimethylamine Here we investigate the molecular interactions between sulfuric acid (sa) and the diamine putrescine (put) using computational methods. The molecular structure of up to four sulfuric acid molecules and up to four putrescine molecules were obtained, at the omega B97X-D/6-31++G(d,p) level of theory. We utilized a domain local pair natural orbital coupled cluster method (DLPNO-CCSD(T)/aug-cc-pVTZ) to obtain highly accurate binding energies of the clusters. We find that the (sa)(1-4)(put)(1-4) clusters show more ionic character than clusters consisting of sulfuric acid and dimethylamine (dma) by readily forming several sulfate ions in the cluster. To estimate the stability of the clusters, we calculate the evaporation rates and compare them to ESI-APi-TOF measurements. Using the atmospheric cluster dynamics code (ACDC), we simulate and compare the new particle formation rates between the (sa)(1-4)(put)(1-4) and (sa),(1-4)(dma)(1-4) cluster systems. We find that putrescine significantly enhances the formation of new particles compared to dimethylamine. Our findings suggest that a large range of amines with different basicity is capable of explaining various regions of the observed new particle formation events. These results indicate that diamines, or related compounds with high basicity, might be important species in forming the initial cluster with sulfuric acid and subsequently more abundant amines with lower basicity can assist in the new particle formation process by attaching to the sulfuric acid-diamine nucleus.
  • Rondo, L.; Ehrhart, S.; Kuerten, A.; Adamov, A.; Bianchi, F.; Breitenlechner, M.; Duplissy, J.; Franchin, A.; Dommen, J.; Donahue, N. M.; Dunne, E. M.; Flagan, R. C.; Hakala, J.; Hansel, A.; Keskinen, H.; Kim, J.; Jokinen, T.; Lehtipalo, K.; Leiminger, M.; Praplan, A.; Riccobono, F.; Rissanen, M. P.; Sarnela, N.; Schobesberger, S.; Simon, M.; Sipilä, M.; Smith, J. N.; Tome, A.; Trostl, J.; Tsagkogeorgas, G.; Vaattovaara, P.; Winkler, P. M.; Williamson, C.; Wimmer, D.; Baltensperger, U.; Kirkby, J.; Kulmala, M.; Petäjä, T.; Worsnop, D. R.; Curtius, J. (2016)
    Sulfuric acid is widely recognized as a very important substance driving atmospheric aerosol nucleation. Based on quantum chemical calculations it has been suggested that the quantitative detection of gas phase sulfuric acid (H2SO4) by use of Chemical Ionization Mass Spectrometry (CIMS) could be biased in the presence of gas phase amines such as dimethylamine (DMA). An experiment (CLOUD7 campaign) was set up at the CLOUD (Cosmics Leaving OUtdoor Droplets) chamber to investigate the quantitative detection of H2SO4 in the presence of dimethylamine by CIMS at atmospherically relevant concentrations. For the first time in the CLOUD experiment, the monomer sulfuric acid concentration was measured by a CIMS and by two CI-APi-TOF (Chemical Ionization-Atmospheric Pressure interface-Time Of Flight) mass spectrometers. In addition, neutral sulfuric acid clusters were measured with the CI-APi-TOFs. The CLOUD7 measurements show that in the presence of dimethylamine (
  • Hurkuck, Miriam; Bruemmer, Christian; Mohr, Karsten; Spott, Oliver; Well, Reinhard; Flessa, Heinz; Kutsch, Werner L. (2015)
    We applied a N-15 dilution technique called Integrated Total Nitrogen Input (ITNI) to quantify annual atmospheric N input into a peatland surrounded by intensive agricultural practices over a 2-year period. Grass species and grass growth effects on atmospheric N deposition were investigated using Lolium multiflorum and Eriophorum vaginatum and different levels of added N resulting in increased biomass production. Plant biomass production was positively correlated with atmospheric N uptake (up to 102.7mg N pot(-1)) when using Lolium multiflorum. In contrast, atmospheric N deposition to Eriophorum vaginatum did not show a clear dependency to produced biomass and ranged from 81.9 to 138.2mgNpot(-1). Both species revealed a relationship between atmospheric N input and total biomass N contents. Airborne N deposition varied from about 24 to 55kgNha(-1)yr(-1). Partitioning of airborne N within the monitor system differed such that most of the deposited N was found in roots of Eriophorum vaginatum while the highest share was allocated in aboveground biomass of Lolium multiflorum. Compared to other approaches determining atmospheric N deposition, ITNI showed highest airborne N input and an up to fivefold exceedance of the ecosystem-specific critical load of 5-10kgNha(-1)yr(-1).
  • Stolzenburg, Dominik; Simon, Mario; Ranjithkumar, Ananth; Kuerten, Andreas; Lehtipalo, Katrianne; Gordon, Hamish; Ehrhart, Sebastian; Finkenzeller, Henning; Pichelstorfer, Lukas; Nieminen, Tuomo; Brilke, Sophia; Xiao, Mao; Amorim, Antonio; Baalbaki, Rima; Baccarini, Andrea; Beck, Lisa; Brakling, Steffen; Murillo, Lucia Caudillo; Chen, Dexian; Chu, Biwu; Dada, Lubna; Dias, Antonio; Dommen, Josef; Duplissy, Jonathan; El Haddad, Imad; Fischer, Lukas; Carracedo, Loic Gonzalez; Heinritzi, Martin; Kim, Changhyuk; Koenig, Theodore K.; Kong, Weimeng; Lamkaddam, Houssni; Lee, Chuan Ping; Leiminger, Markus; Li, Zijun; Makhmutov, Vladimir; Manninen, Hanna E.; Marie, Guillaume; Marten, Ruby; Mueller, Tatjana; Nie, Wei; Partoll, Eva; Petaja, Tuukka; Pfeifer, Joschka; Philippov, Maxim; Rissanen, Matti P.; Rorup, Birte; Schobesberger, Siegfried; Schuchmann, Simone; Shen, Jiali; Sipila, Mikko; Steiner, Gerhard; Stozhkov, Yuri; Tauber, Christian; Tham, Yee Jun; Tome, Antonio; Vazquez-Pufleau, Miguel; Wagner, Andrea C.; Wang, Mingyi; Wang, Yonghong; Weber, Stefan K.; Wimmer, Daniela; Wlasits, Peter J.; Wu, Yusheng; Ye, Qing; Zauner-Wieczorek, Marcel; Baltensperger, Urs; Carslaw, Kenneth S.; Curtius, Joachim; Donahue, Neil M.; Flagan, Richard C.; Hansel, Armin; Kulmala, Markku; Lelieveld, Jos; Volkamer, Rainer; Kirkby, Jasper; Winkler, Paul M.; He, Xucheng (2020)
    In the present-day atmosphere, sulfuric acid is the most important vapour for aerosol particle formation and initial growth. However, the growth rates of nanoparticles (<10 nm) from sulfuric acid remain poorly measured. Therefore, the effect of stabilizing bases, the contribution of ions and the impact of attractive forces on molecular collisions are under debate. Here, we present precise growth rate measurements of uncharged sulfuric acid particles from 1.8 to 10 nm, performed under atmospheric conditions in the CERN (European Organization for Nuclear Research) CLOUD chamber. Our results show that the evaporation of sulfuric acid particles above 2 nm is negligible, and growth proceeds kinetically even at low ammonia concentrations. The experimental growth rates exceed the hard-sphere kinetic limit for the condensation of sulfuric acid. We demonstrate that this results from van derWaals forces between the vapour molecules and particles and disentangle it from charge-dipole interactions. The magnitude of the enhancement depends on the assumed particle hydration and collision kinetics but is increasingly important at smaller sizes, resulting in a steep rise in the observed growth rates with decreasing size. Including the experimental results in a global model, we find that the enhanced growth rate of sulfuric acid particles increases the predicted particle number concentrations in the upper free troposphere by more than 50 %.
  • Myllys, Nanna; Ponkkonen, Tuomo; Chee, Sabrina; Smith, James (2020)
    The role of an oxidation product of trimethylamine, trimethylamine oxide, in atmospheric particle formation is studied using quantum chemical methods and cluster formation simulations. Molecular-level cluster formation mechanisms are resolved, and theoretical results on particle formation are confirmed with mass spectrometer measurements. Trimethylamine oxide is capable of forming only one hydrogen bond with sulfuric acid, but unlike amines, trimethylamine oxide can form stable clusters via ion-dipole interactions. That is because of its zwitterionic structure, which causes a high dipole moment. Cluster growth occurs close to the acid:base ratio of 1:1, which is the same as for other monoprotic bases. Enhancement potential of trimethylamine oxide in particle formation is much higher than that of dimethylamine, but lower compared to guanidine. Therefore, at relatively low concentrations and high temperatures, guanidine and trimethylamine oxide may dominate particle formation events over amines.
  • Kontkanen, Jenni; Olenius, Tinja; Kulmala, Markku; Riipinen, Ilona (2018)
    Atmospheric new particle formation (NPF) occurs by the formation of nanometer-sized molecular clusters and their subsequent growth to larger particles. NPF involving sulfuric acid, bases and oxidized organic compounds is an important source of atmospheric aerosol particles. One of the mechanisms suggested to depict this process is nano-Kohler theory, which describes the activation of inorganic molecular clusters to growth by a soluble organic vapor. In this work, we studied the capability of nano-Kohler theory to describe the initial growth of atmospheric molecular clusters by simulating the dynamics of a cluster population in the presence of a sulfuric acid-base mixture and an organic compound. We observed nano-Kohler-type activation in our simulations when the saturation ratio of the organic vapor and the ratio between organic and inorganic vapor concentrations were in a suitable range. However, nano-Kohler theory was unable to predict the exact size at which the activation occurred in the simulations. In some conditions, apparent cluster growth rate (GR) started to increase close to the activation size determined from the simulations. Nevertheless, because the behavior of GR is also affected by other dynamic processes, GR alone cannot be used to deduce the cluster growth mechanism.
  • Besel, Vitus; Kubecka, Jakub; Kurten, Theo; Vehkamäki, Hanna (2020)
    We tested the influence of various parameters on the new particle formation rate predicted for the sulfuric acid–ammonia system using quantum chemistry and cluster distribution dynamics simulations, in our case, Atmospheric Cluster Dynamics Code (ACDC). We found that consistent consideration of the rotational symmetry number of monomers (sulfuric acid and ammonia molecules, and bisulfate and ammonium ions) leads to a significant rise in the predicted particle formation rate, whereas inclusion of the rotational symmetry number of the clusters only changes the results slightly, and only in conditions where charged clusters dominate the particle formation rate. This is because most of the clusters stable enough to participate in new particle formation have a rotational symmetry number of 1, and few exceptions to this rule are positively charged clusters. In contrast, the application of the quasi-harmonic correction for low-frequency vibrational modes tends to generally decrease predicted new particle formation rates and also significantly alters the slope of the formation rate curve plotted against the sulfuric acid concentration, which is a typical convention in atmospheric aerosol science. The impact of the maximum size of the clusters explicitly included in the simulations depends on the simulated conditions. The errors arising from a limited set of clusters are higher for higher evaporation rates, and thus tend to increase with temperature. Similarly, the errors tend to be higher for lower vapor concentrations. The boundary conditions for outgrowing clusters (that are counted as formed particles) have only a small influence on the results, provided that the definition is chemically reasonable and that the set of simulated clusters is sufficiently large. A comparison with data from the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber and a cluster distribution dynamics model using older quantum chemistry input data shows improved agreement when using our new input data and the proposed combination of symmetry and quasi-harmonic corrections.
  • Auddy, Sayantan; Myers, Philip C.; Basu, Shantanu; Harju, Jorma; Pineda, Jaime E.; Friesen, Rachel K. (2019)
    We develop a new "core field structure" (CFS) model to predict the magnetic field strength and magnetic field fluctuation profile of dense cores using gas kinematics. We use spatially resolved observations of the nonthermal velocity dispersion from the Green Bank Ammonia survey along with column density maps from SCUBA-2 to estimate the magnetic field strength across seven dense cores located in the L1688 region of Ophiuchus. The CFS model predicts the profile of the relative field fluctuation, which is related to the observable dispersion in the direction of the polarization vectors. Within the context of our model, we find that all of the cores have a transcritical mass-to-flux ratio.
  • Wang, Mingyi; He, Xu-Cheng; Finkenzeller, Henning; Iyer, Siddharth; Chen, Dexian; Shen, Jiali; Simon, Mario; Hofbauer, Victoria; Kirkby, Jasper; Curtius, Joachim; Maier, Norbert; Kurten, Theo; Worsnop, Douglas; Kulmala, Markku; Rissanen, Matti; Volkamer, Rainer; Tham, Yee Jun; Donahue, Neil M.; Sipilä, Mikko (2021)
    Iodine species are important in the marine atmosphere for oxidation and new-particle formation. Understanding iodine chemistry and iodine new-particle formation requires high time resolution, high sensitivity, and simultaneous measurements of many iodine species. Here, we describe the application of a bromide chemical ionization mass spectrometer (Br-CIMS) to this task. During the iodine oxidation experiments in the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber, we have measured gas-phase iodine species and sulfuric acid using two Br-CIMS, one coupled to a Multi-scheme chemical IONization inlet (Br-MION-CIMS) and the other to a Filter Inlet for Gasses and AEROsols inlet (Br-FIGAERO-CIMS). From offline calibrations and intercomparisons with other instruments, we have quantified the sensitivities of the Br-MIONCIMS to HOI, I-2, and H2SO4 and obtained detection limits of 5.8 x 10(6), 3.8 x 10(5), and 2.0 x 10(5) molec. cm(-3), respectively, for a 2 min integration time. From binding energy calculations, we estimate the detection limit for HIO3 to be 1.2 x 10(5) molec. cm(-3), based on an assumption of maximum sensitivity. Detection limits in the Br-FIGAERO-CIMS are around 1 order of magnitude higher than those in the Br-MION-CIMS; for example, the detection limits for HOI and HIO3 are 3.3 x 10(7) and 5.1 x 10(6) molec. cm(-3), respectively. Our comparisons of the performance of the MION inlet and the FIGAERO inlet show that bromide chemical ionization mass spectrometers using either atmospheric pressure or reduced pressure interfaces are well-matched to measuring iodine species and sulfuric acid in marine environments.
  • Chronopoulou, Myrsini; Salonen, Iines; Bird, Clare; Reichart, Gert-Jan; Koho, Karoliina (2019)
    Foraminifera are ubiquitous marine protists with an important role in the benthic carbon cycle. However, morphological observations often fail to resolve their exact taxonomic placement and there is a lack of field studies on their particular trophic preferences. Here, we propose the application of metabarcoding as a tool for the elucidation of the in situ feeding behavior of benthic foraminifera, while also allowing the correct taxonomic assignment of the feeder, using the V9 region of the 18S (small subunit; SSU) rRNA gene. Living foraminiferal specimens were collected from two intertidal mudflats of the Wadden Sea and DNA was extracted from foraminiferal individuals and from the surrounding sediments. Molecular analysis allowed us to confirm that our foraminiferal specimens belong to three genetic types: Ammonia sp. T6, Elphidium sp. S5 and Haynesina sp. S16. Foraminiferal intracellular eukaryote communities reflected to an extent those of the surrounding sediments but at different relative abundances. Unlike sediment eukaryote communities, which were largely determined by the sampling site, foraminiferal intracellular eukaryote communities were driven by foraminiferal species, followed by sediment depth. Our data suggests that Ammonia sp. T6 can predate on metazoan classes, whereas Elphidium sp. S5 and Haynesina sp. S16 are more likely to ingest diatoms. These observations, alongside the use of metabarcoding in similar ecological studies, significantly contribute to our overall understanding of the ecological roles of these protists in intertidal benthic environments and their position and function in the benthic food webs.
  • Sipilä, O.; Caselli, P.; Harju, J. (2019)
    We constructed two new models for deuterium and spin-state chemistry for the purpose of modeling the low-temperature environment prevailing in starless and pre-stellar cores. The fundamental difference between the two models is in the treatment of ion-molecule proton-donation reactions of the form XH+ + Y -> X + YH+, which are allowed to proceed either via full scrambling or via direct proton hop, that is, disregarding proton exchange. The choice of the reaction mechanism affects both deuterium and spin-state chemistry, and in this work our main interest is on the effect on deuterated ammonia. We applied the new models to the starless core H-MM1, where several deuterated forms of ammonia have been observed. Our investigation slightly favors the proton hop mechanism over full scrambling because the ammonia D/H ratios are better fit by the former model, although neither model can reproduce the observed NH2D ortho-to-para ratio of 3 (the models predict a value of similar to 2). Extending the proton hop scenario to hydrogen atom abstraction reactions yields a good agreement for the spin-state abundance ratios, but greatly overestimates the deuterium fractions of ammonia. However, one can find a reasonably good agreement with the observations with this model by increasing the cosmic-ray ionization rate over the commonly adopted value of similar to 10(-17) s(-1). We also find that the deuterium fractions of several other species, such as H2CO, H2O, and CH3, are sensitive to the adopted proton-donation reaction mechanism. Whether the full scrambling or proton hop mechanism dominates may be dependent on the reacting system, and new laboratory and theoretical studies for various reacting systems are needed to constrain chemical models.
  • Almeida, Joao; Schobesberger, Siegfried; Kuerten, Andreas; Ortega, Ismael K.; Kupiainen, Oona; Praplan, Arnaud P.; Adamov, Alexey; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; David, Andre; Dommen, Josef; Donahue, Neil M.; Downard, Andrew; Dunne, Eimear; Duplissy, Jonathan; Ehrhart, Sebastian; Flagan, Richard C.; Franchin, Alessandro; Guida, Roberto; Hakala, Jani; Hansel, Armin; Heinritzi, Martin; Henschel, Henning; Jokinen, Tuija; Junninen, Heikki; Kajos, Maija; Kangasluoma, Juha; Keskinen, Helmi; Kupc, Agnieszka; Kurten, Theo; Kvashin, Alexander N.; Laaksonen, Ari; Lehtipalo, Katrianne; Leiminger, Markus; Leppa, Johannes; Loukonen, Ville; Makhmutov, Vladimir; Mathot, Serge; McGrath, Matthew J.; Nieminen, Tuomo; Olenius, Tinja; Onnela, Antti; Petäjä, Tuukka; Riccobono, Francesco; Riipinen, Ilona; Rissanen, Matti; Rondo, Linda; Ruuskanen, Taina; Santos, Filipe D.; Sarnela, Nina; Schallhart, Simon; Schnitzhofer, Ralf; Seinfeld, John H.; Simon, Mario; Sipilä, Mikko; Stozhkov, Yuri; Stratmann, Frank; Tome, Antonio; Troestl, Jasmin; Tsagkogeorgas, Georgios; Vaattovaara, Petri; Viisanen, Yrjo; Virtanen, Annele; Vrtala, Aron; Wagner, Paul E.; Weingartner, Ernest; Wex, Heike; Williamson, Christina; Wimmer, Daniela; Ye, Penglin; Yli-Juuti, Taina; Carslaw, Kenneth S.; Kulmala, Markku; Curtius, Joachim; Baltensperger, Urs; Worsnop, Douglas R.; Vehkamäki, Hanna; Kirkby, Jasper (2013)
  • Kuerten, Andreas; Jokinen, Tuija; Simon, Mario; Sipilä, Mikko; Sarnela, Nina; Junninen, Heikki; Adamov, Alexey; Almeida, Joao; Amorim, Antonio; Bianchi, Federico; Breitenlechner, Martin; Dommen, Josef; Donahue, Neil M.; Duplissy, Jonathan; Ehrhart, Sebastian; Flagan, Richard C.; Franchin, Alessandro; Hakala, Jani; Hansel, Armin; Heinritzi, Martin; Hutterli, Manuel; Kangasluoma, Juha; Kirkby, Jasper; Laaksonen, Ari; Lehtipalo, Katrianne; Leiminger, Markus; Makhmutov, Vladimir; Mathot, Serge; Onnela, Antti; Petäjä, Tuukka; Praplan, Arnaud P.; Riccobono, Francesco; Rissanen, Matti P.; Rondo, Linda; Schobesberger, Siegfried; Seinfeld, John H.; Steiner, Gerhard; Tome, Antonio; Troestl, Jasmin; Winkler, Paul M.; Williamson, Christina; Wimmer, Daniela; Ye, Penglin; Baltensperger, Urs; Carslaw, Kenneth S.; Kulmala, Markku; Worsnop, Douglas R.; Curtius, Joachim (2014)