A Review of More Than 20 Years of Aerosol Observation at the High Altitude Research Station Jungfraujoch, Switzerland (3580 m asl)
Among the worldwide existing long-term aerosol monitoring sites, the Jungfraujoch (JFJ) belongs to the category where both free tropospheric (FT) conditions and influence from planetary boundary layer (PBL) injections can be observed. Thus, it is possible to characterize free tropospheric aerosol as well as the effects of vertical transport of more polluted air from the PBL. This paper summarizes the current knowledge of the key properties for the JFJ aerosol, gained from the large number of in-situ studies from more than 20 years of aerosol measurements at the site. This includes physical, chemical and optical aerosol properties as well as aerosol-cloud interactions and cloud characteristics. It is illustrated that the aerosol size distribution and the aerosol chemical composition are fairly constant in time due to the long distance from aerosol sources, and that many climate relevant aerosol properties can be derived due to this behavior.
A transition metal oxofluoride offering advantages in electrocatalysis and potential use in applications
Bioconcentration of Dissolved Organic Compounds from Oil Sands Process-Affected Water by Medaka (Oryzias latipes): Importance of Partitioning to Phospholipids
The complex mixture of dissolved organics in oil sands process-affected water (OSPW) is acutely lethal to fish at environmentally relevant concentrations, but few bioconcentration factors (BCFs) have been measured for its many chemical species. Japanese medaka (Oryzias latipes) were exposed to 10% OSPW, and measured BCFs were evaluated against predicted BCFs from octanol water distribution ratios (D-OW) and phospholipid membrane water distribution ratios (D-MW). Two heteroatomic chemical classes detected in positive ion mode (SO+, NO+) and one in negative mode (O-2(-), also known as naphthenic acids) had the greatest D-MW, values, as high as 10 000. Estimates of D-MW were similar to and correlated with D-OW for O+, O-2(+), SO+, and NO+ chemical species, but for O-2 and SO2 species the D-MW values were much greater than the corresponding D-OW, suggesting the importance of electrostatic interactions for these ionizable organic acids. Only SO+, NO+, and O-2(-) species were detectable in medaka exposed to OSPW, and BCFs for SO+ and NO+ species ranged from 0.6 to 28 L/kg, lower than predicted (i.e., 1.4-1.7 X 10(3) L/kg), possibly because of biotransformation of these hydrophobic substances. BCFs of O-2(-) species ranged from 0.7 to 53 L/kg, similar to predicted values and indicating that phospholipid partitioning was an important bioconcentration mechanism.
Carbon isotope composition of carbohydrates and polyols in leaf and phloem sap of Phaseolus vulgaris L. influences predictions of plant water use efficiency
Unexpectedly acidic nanoparticles formed in dimethylamine-ammonia-sulfuric-acid nucleation experiments at CLOUD
New particle formation driven by acid-base chemistry was initiated in the CLOUD chamber at CERN by introducing atmospherically relevant levels of gas-phase sulfuric acid and dimethylamine (DMA). Ammonia was also present in the chamber as a gas-phase contaminant from earlier experiments. The composition of particles with volume median diameters (VMDs) as small as 10 nm was measured by the Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS). Particulate ammonium-to-dimethylaminium ratios were higher than the gas-phase ammonia-to-DMA ratios, suggesting preferential uptake of ammonia over DMA for the collected 10-30 nm VMD particles. This behavior is not consistent with present nanoparticle physicochemical models, which predict a higher dimethylaminium fraction when NH3 and DMA are present at similar gas-phase concentrations. Despite the presence in the gas phase of at least 100 times higher base concentrations than sulfuric acid, the recently formed particles always had measured base : acid ratios lower than 1 : 1. The lowest base fractions were found in particles below 15 nm VMD, with a strong size-dependent composition gradient. The reasons for the very acidic composition remain uncertain, but a plausible explanation is that the particles did not reach thermodynamic equilibrium with respect to the bases due to rapid heterogeneous conversion of SO2 to sulfate. These results indicate that sulfuric acid does not require stabilization by ammonium or dimethylaminium as acid-base pairs in particles as small as 10 nm.
Highly functionalized organic nitrates in the southeast United States: Contribution to secondary organic aerosol and reactive nitrogen budgets
Speciated particle-phase organic nitrates (pONs) were quantified using online chemical ionization MS during June and July of 2013 in rural Alabama as part of the Southern Oxidant and Aerosol Study. A large fraction of pONs is highly functionalized, possessing between six and eight oxygen atoms within each carbon number group, and is not the common first generation alkyl nitrates previously reported. Using calibrations for isoprene hydroxynitrates and the measured molecular compositions, we estimate that pONs account for 3% and 8% of total submicrometer organic aerosol mass, on average, during the day and night, respectively. Each of the isoprene-and monoterpenes-derived groups exhibited a strong diel trend consistent with the emission patterns of likely biogenic hydrocarbon precursors. An observationally constrained diel box model can replicate the observed pON assuming that pONs (i) are produced in the gas phase and rapidly establish gas-particle equilibrium and (ii) have a short particle-phase lifetime (similar to 2-4 h). Such dynamic behavior has significant implications for the production and phase partitioning of pONs, organic aerosol mass, and reactive nitrogen speciation in a forested environment.