Name: Third workshop on Air-Ice Chemical Interactions (AICI)
Start: 2011-06-06T08:00:00-04:00
End: 2011-06-08T23:00:00-04:00
Location: Columbia University

Third workshop on Air-Ice Chemical Interactions (AICI)

from Monday, 6 June 2011 (08:00) to Wednesday, 8 June 2011 (23:00)

Monday, 6 June 2011

08:00 Registration Desk (outside Davis Auditorium)
Registration Desk (outside Davis Auditorium)
08:00 - 09:00

09:00 Welcome & Scope & Reviews
Welcome & Scope & Reviews
09:00 - 09:20
What the meeting is for, presentation of the 3 review papers, info on local arragements

09:20

09:20 - 12:05
Organics in Snow and Ice: Recent Findings from Field and Modeling Studies - Amanda Grannas (Villanova University)
Organics in Snow and Ice: Recent Findings from Field and Modeling Studies
- Amanda Grannas (Villanova University)
09:20 - 09:50
It has become increasingly apparent that snow and ice are important media for both homogeneous and heterogeneous environmental chemical reactions. A variety of chemistry occurs in/on snow and ice, including photochemical, redox and biologically-mediated reactions. Organic components play an important role in many of these processes. Organics can be the reactive chromophore or a photosensitizer in photochemical processes; they may take part in electron shuttling for redox processes; or they can serve the role of carbon source for biological metabolism. These myriad processes all play an important role in the exchange of reactive species between snow and the atmosphere. This presentation will focus on the state of the science with respect to identifying and characterizing organic materials present in snow and ice, and the interactions of snow and ice in the environment with VOCs, from a field and modeling perspective.
09:50 Marcello Guzman: organics - mechanism - Marcelo Guzman (University of Kentucky)
Marcello Guzman: organics - mechanism
- Marcelo Guzman (University of Kentucky)
09:50 - 10:20
10:20 Coffee & put posters up
Coffee & put posters up
10:20 - 10:50
10:50 Carbonaceous species and HUmic LIke Substances in Arctic Snow: contribution to the speciation of total carbon and optical properties during OASIS – Barrow 2009 campaign. - D. Voisin (UJF-grenoble / CNRS, LGGE, BP 96, 38402 St Martin d’Heres, France)
Carbonaceous species and HUmic LIke Substances in Arctic Snow: contribution to the speciation of total carbon and optical properties during OASIS – Barrow 2009 campaign.
- D. Voisin (UJF-grenoble / CNRS, LGGE, BP 96, 38402 St Martin d’Heres, France)
10:50 - 11:10
Carbonaceous species play critical roles in the interaction of snow with the overlying atmosphere. Elemental or Black Carbon strongly decreases snow albedo, therefore influencing the snow-climate feedback loop. Carbonyls and complex organic molecules such as Humic Like Substances also absorb UV and visible light, therefore influencing photochemistry and light penetration depths in the snowpack. It has been proposed that some of those complex organic molecules, acting as electron donors in photochemical reactions might change the photolysis paths of nitric acid from NO / NO2 to HONO. Yet, global investigations of the organic matter in arctic snowpack are scarce, and often limited to a few specific species. During the OASIS campaign in Barrow, 2009, we investigated the global carbonaceous content of continental snowpack. On most samples, analysis included Dissolved Organic Carbon, short chain mono and di-carboxylic acids (ion chromatography), and some aldehydes (LC-fluorimetry). Additional samples were also analyzed for EC and Water Insoluble Organic Carbon. This enables to discuss the contribution of various carbon fraction to the total carbon load of the snowpack, as a function of snowtypes A small subset of samples was used to isolate HULIS fraction. Their carbon content was measured together with their UV-Vis absorption spectrum. This enables us to calculate spectral mass absorptivities for HULIS in snow and the contribution of HULIS to the total absorbance measured separately on melted snow samples, and to discuss their potential contribution to snow photochemistry.
11:10 The Applicability of Artificial Snow for Environmental Studies - Petr Klan (Masaryk University, Brno, Czech republic)
The Applicability of Artificial Snow for Environmental Studies
- Petr Klan (Masaryk University, Brno, Czech republic)
11:10 - 11:30
The freezing of aqueous solutions of most of the organic (and inorganic) compounds causes ice and solute molecules to separate. It results in their increased local concentrations in a liquid (or quasi-liquid) phase covering the ice crystal surface or residing in a limited volume, referred to as micropockets, at the boundary of solid ice. Contrary to this, a shock freezing preparation technique can produce artificial snow grains which grow freely without the physical restrictions. Recently we investigated the surface coverage of artificial snow grains by organic contaminants in relation to their surface self-association, diffusion, and bimolecular reactions. Our study revealed that hydrophobic organic molecules can be located on the surface of snow grains in associations rather than as isolated species even at very low concentrations. It is demonstrated that snow represents a readily available study matrix that can be used to emulate the natural chemical processes of trace contaminants occurring in natural snow and stratospheric cloud particles.
11:30 Speciation, location, and reactivity of aldehydes in snow - Florent Domine (CNRS, Glaciology Laboratory) Didier Voisin (CNRS, Glaciology Laboratory)
Speciation, location, and reactivity of aldehydes in snow
- Florent Domine (CNRS, Glaciology Laboratory)
- Didier Voisin (CNRS, Glaciology Laboratory)
11:30 - 11:50
Aldehydes are key reactive species produced by photochemical processes in the snow. They have the potential to be released to the atmosphere, affecting its oxidative capacity. We have performed measurements of formaldehyde, acetaldehyde, glyoxal and methylglyoxal in polar snow, and in particular at Barrow, Alaska, where atmospheric mixing ratios of formaldehyde were also measured. The predominant aldehyde is formaldehyde, HCHO. Based on recent laboratory studies of HCHO diffusion and solubility in ice, we demonstrate that HCHO forms a solid solution with ice and that the variations of its concentrations in snow can be explained by solid state diffusion in and out of snow grains. Events are observed where HCHO concentrations in snow increase, while HCHO is also emitted by snow, demonstrating a photochemical source of HCHO in the snow. Acetaldehyde, glyoxal and methylglyoxal concentrations are correlated to those of formaldehyde. However, the lack of basic data on the interactions of those species with ice, and the absence of measurement of their atmospheric mixing ratios prevents a detailed quantitative interpretation of their concentrations. Together, these three species can be as abundant as formaldehyde, so that their role can be important and warrant further studies.
11:50 short discussion
short discussion
11:50 - 12:05
12:05
12:05 - 13:15
Contributions

12:05 Nitrate and Protons at the Air-Ice Interface - Sumi Wren (University of Toronto)

12:05 BRDF measurements of the spectral reflectivity of Antarctic sea-ice: The first results from the deployment of the GRASS system. - Martin King (Royal Holloway University of London)

12:05 Can HULIS and Black carbon explain the absorption properties of Polar snows and their effects on the rate of photo-production of radicals in the snowpack? - Martin King (Royal Holloway University of London)

12:05 Investigation of boundary layer photochemistry at the WAIS-Divide site through measurement of major photochemically active species in snow and air - Sylvain M. Masclin (University of California, Merced)

12:05 The Effect of Liquid-Like Layers on the Interaction of Nitric Acid with Ice Surfaces - Samar Moussa (Columbia University)

12:05 The depth of UV light extinction (e-folding depths) at Summit, Greenland - Patrick Wright (University of Houston)

12:05 Freeze-Induced Reactions: Formation of Iodine−Bromine Interhalogen Species from Aqueous Halide Ion Solutions - Daniel O'Sullivan (University College Cork)

12:05 Model simulations of polar boundary layer ozone depletion events in spring - Xin Yang (University of Cambridge)

12:05 Modelling of the interaction of halogenated molecules with the ice surface - Céline TOUBIN (PHLAM)

12:05 Exploring high resolution measurements of ozone depletion chemistry in coastal Antarctica through use of a 1D marine boundary layer chemistry model (MISTRA) - Zak Buys (British Antarctic Survey)

12:05 Liquid-like layers on ice in the environment: bridging the quasi-liquid and brine layer paradigms - Min H. Kuo (Department of Chemical Engineering, Columbia University, New York, NY USA 10027)

12:05 Interactions of hydroxyl radicals with ice: A molecular dynamics study - Tara Kahan (University of Colorado Boulder)

12:05 Ice Photochemistry Mediated by Dissolved Organic Matter: Degradation of Persistent Organic Pollutants - Amanda Grannas (Villanova University)

12:05 The Effect of the Novel HNO3(g) Production - Christopher Boxe (NASA-JPL)

12:05 Overview of the NITEDC (NItrate Evolution in Dome C snow) program and presentation of its preliminary results - Markus Frey (British Antarctic Survey)

12:05 Pernitric and nitric acid in a coastal Antarctic boundary layer – a winter time study - Markus Frey (British Antarctic Survey)

12:05 Photochemistry of Model Organic Matter in Ice - Marcelo Guzman (University of Kentucky)

12:05 Investigating Brine on Frost Flowers with Absorption Tomography - Peter Peterson (Geophysical Institute and Department of Chemistry and Biochemistry, University of Alaska Fairbanks)

12:05 Post-depositional fractionation of nitrate stable isotopes in Antarctic snow: towards an ice core proxy of surface UV - Markus Frey (British Antarctic Survey)

12:05 Reactive nitrogen chemistry in surface snow during the OASIS spring campaign 2009 at Barrow, AK - Hans-Werner Jacobi (Laboratoire de Glaciologie et Géophysique de l’Environnement LGGE)

12:05 Probing the liquid-like surface of frozen salt solutions via infrared spectroscopy - Rebecca Michelsen (Randolph-Macon College)

12:05 Simulating the fate of cryospheric mercury - Dorothy Durnford (Independent researcher)

12:05 Greenland Summit HOx/Halogen Experiment: 2007 and 2008 - Jennie Thomas (LATMOS/UCLA)

12:05 Chemical composition of the snowpack during the OASIS spring campaign 2009 at Barrow, AK - Hans-Werner Jacobi (Laboratoire de Glaciologie et Géophysique de l’Environnement LGGE)

12:05 The Adsorption of HO2NO2 on Ice - Thorsten Bartels-Rausch (Paul Scherrer Institut)
13:15

13:15 - 15:10
Perspective on Halogens - Paul Shepson Shepson (Purdue University)
Perspective on Halogens
- Paul Shepson Shepson (Purdue University)
13:15 - 13:45
13:45 Exploring new pathways on ice - John Sodeau (University College Cork)
Exploring new pathways on ice
- John Sodeau (University College Cork)
13:45 - 14:15
Snow-packs, cirrus clouds, polar stratospheric clouds, frost flowers and sea-ices can all be viewed as part of the Earth’s Cryosphere. Not mere spectactors on chemistry in the atmosphere, ices often play an active role due to the presence of their surfaces, triple points and internal pores. The effects manifest as rate changes for known chemical processes as well as the promotion of “unexpected” pathways. Therefore in this talk some new results on a number of systems relevant to atmospheric processing on ice surfaces will be discussed. The first topic concerns the influence of freezing on the chemical composition of halide ions in dilute aqueous solutions. The “freeze-enhanced” chemistry discussed is particularly relevant to the anomalously high levels of halogen oxides observed in the Polar troposphere. The focus then moves to investigations of the low-temperature reactivities of sulfur dioxide on/within ices using FT-RAIRS and TPD as probes of the chemistry. Similar methodologies are adopted for an investigation of the low-temperature photochemistry of organo-nitrates in the presence of water-ice surfaces. The question to be answered here is: are these long-lived compounds, which are mainly anthropogenic in origin, transformed by heterogeneous processing on cryospheric ice surfaces? Finally the dark oxidation of dissolved gaseous mercury in ice will be illustrated from experiments based on atomic fluorescence detection. Very few results on the chemical interaction between mercury and water-ices are available to the atmospheric chemistry community currently and the data obtained in this work clearly show that freezing does play an effect on the oxidation processes studied.
14:15 The Importance of Sea Ice for Halocarbon and Mercury Chemistry - Anna Granfors (University of Gothenburg, Sweden) Katarina Abrahamsson (University of Gothenburg, Sweden)
The Importance of Sea Ice for Halocarbon and Mercury Chemistry
- Anna Granfors (University of Gothenburg, Sweden)
- Katarina Abrahamsson (University of Gothenburg, Sweden)
14:15 - 14:35
Sea ice is thought of as being a barrier for the transportation of dissolved gases between the ocean and the atmosphere. However, sea ice as a source of gases has not been considered to any larger extent. The gaseous fluxes of halocarbons and mercury in polar waters are poorly known, particularly in regards to the role of sea ice. The fluxes are predicted to change in accordance with changes in the biological processes and by melting of sea ice resulting in more open water. The ice is a habitat for a number of autotrophic and heterotrophic organisms. It is a highly variable ecosystem governed by salinity, temperature, limitation in nutrients as well as light conditions. Sea ice is also a barrier to light transmission, and, therefore, ice algae must be physiologically adapted to low light conditions. It has been shown that their photosynthetic systems are saturated at relatively low light intensities, and have high photosynthetic efficiencies. A consequence of such high activity is an increase in pH as well as a depletion of inorganic carbon. We have measured the distribution of halocarbons and mercury in sea ice and snow during expeditions to the Amundsen Sea, Antarctica, with the Swedish icebreaker Oden. Our results indicate sea ice as a source of halocarbons, in particular iodinated compounds. For the latter ones the contribution to the atmosphere is in the same order of magnitude as that of seawater. The importance of irradiance for the distribution of dissolved gaseous mercury in ice cores was also studied. The difference in concentrations of volatile mercury was significantly altered due to different light conditions. This indicates that photo reduction of oxidized mercury is occurring in ice, possibly in the aqueous fractions, brine, within the ice structure.
14:35 1D multiphase modeling of NOx and halogen photochemistry at Summit, Greenland using MISTRA-SNOW - Jennie Thomas (LATMOS/UCLA)
1D multiphase modeling of NOx and halogen photochemistry at Summit, Greenland using MISTRA-SNOW
- Jennie Thomas (LATMOS/UCLA)
14:35 - 14:55
Motivated by observations of reactive halogens and NOx at Summit, Greenland in the center of the Greenland ice sheet we have developed a 1D model for snow physics and chemistry. This model has been coupled to the boundary layer model MISTRA, which includes detailed multiphase chemistry in the atmosphere and snow. We have developed the model with the goal of understanding how chemical species evolve with time in the interstitial air and to study the interplay between the chemistry in and above the snow. Measurements of gas phase bromine species were undertaken as part of the GSHOX field campaign, conduced during summer 2007 and 2008 at Summit Research Station on the Greenland ice sheet. We compare model results with data collected from the field including meteorology, as well as observed NO and BrO mixing ratios. We have found that both ambient NO and BrO mixing ratios can be explained by fluxes out of the snow pack. The methodology for modeling the multiphase in-snow chemistry will be presented along with results from the model, including vertical profiles of halogens in the snow pack and in the atmosphere along with their evolution in time.
14:55 short discussion
short discussion
14:55 - 15:10

15:10

15:10 - 15:40

15:40 General Discussion and questions
General Discussion and questions
15:40 - 16:10

16:10 General Discussion about Review Paper
General Discussion about Review Paper
16:10 - 17:30

18:00 Dinner
Dinner
18:00 - 21:00
Tuesday, 7 June 2011
09:00 Atmospheric nitrogen oxides (NO and NO2) at Dome C: first observations & implications for reactive nitrogen cycling above the East Antarctic Ice Sheet - Markus Frey (British Antarctic Survey)
Atmospheric nitrogen oxides (NO and NO2) at Dome C: first observations & implications for reactive nitrogen cycling above the East Antarctic Ice Sheet
- Markus Frey (British Antarctic Survey)
09:00 - 09:20
The nitrogen oxides NO and NO2 (NOx) play a key role in determining the oxidizing capacity of the boundary layer in high latitudes. Previous Arctic and Antarctic field campaigns have demonstrated that the polar snow pack can release significant amounts of NOx and that one of the major driving mechanisms is UV-photolysis of snow nitrate (NO3-). Unusually high levels of NO observed at South Pole and on an airborne campaign suggested that the East Antarctic Ice Sheet (EAIS) can be perceived as a gigantic chemical reactor, processing many chemical trace species at the surface and thereby modifying their concentration eventually preserved in ice cores. However, the database for a quantitative understanding of reactive nitrogen recycling across Antarctica is still weak. First measurements of atmospheric NOx mixing ratios at Dome C (DC), East Antarctica (75.1ºS 123.3ºE, 3233 m) during austral summer 2009/2010 yield new insights: NOx mixing ratios were large, ranging between 3 pptv and >1000 pptv, but unlike at South Pole showed a strong diurnal variability. Concentration maxima in ambient air at 0.01, 1.0 and 4.0m above the snow occurred in the evening hours. They coincided with the strongest concentration gradients between the snow surface and 4.0 m, highlighting the importance of the interplay between snow pack source strength and the evolution of the boundary layer diffusivity profile. Conversely, near-surface firn air levels of NOx varied in phase with solar radiation, consistent with a photolytic source in the near-surface snow. Steady-state analysis shows strong increases in the Leighton ratio around solar noon, confirming the importance of oxidants other than ozone, i.e. hydroxyl radicals. Comparison of observations with a potential NO2 flux based on a radiation transfer model (TUV-snow) allows to improve the parameterization of NOx emissions in a quantitative model of reactive nitrogen recycling above Antarctica.
09:00 - 10:55
09:20 On or in? Where does atmospheric ice chemistry occur? - James DONALDSON (Department of Chemistry, University of Torontro)
On or in? Where does atmospheric ice chemistry occur?
- James DONALDSON (Department of Chemistry, University of Torontro)
09:20 - 09:50
Chemical reactions of importance to the atmosphere are generally assumed to take place at the air-ice interface, where a combination of atmospheric deposition and solute exclusion are thought to give rise to high reagent concentrations. Using glancing-angle fluorescence and Raman spectroscopies we have made direct measurements of photochemical and bimolecular kinetics at this interface, and compared the results with those obtained using more traditional techniques. We find that the ice and liquid water surfaces show very different reactive natures. The liquid surface and bulk kinetics are consistent with bulk ice results and the ice surface typically different by up to an order of magnitude. As well, we have shown that solute exclusion to the air-ice interface is neither complete, nor always well predicted by the relevant phase diagram.
09:50 The ice - air interface in snow - the molecular to micron scale perspective - Markus Ammann (Paul Scherrer Institut)
The ice - air interface in snow - the molecular to micron scale perspective
- Markus Ammann (Paul Scherrer Institut)
09:50 - 10:20
Ice is a high temperature material in the sense that under environmental conditions it is close to its melting temperature. This leads to peculiarities that determine the physical and chemical properties of the ice - air interface but also the larger scale snow structure. While this is reasonably well understood for pure ice, contaminants present in environmental snow interact with the structure of ice and are believed to significantly alter the ice surface. This overview presents results of novel spectroscopic experiments that directly probe this interface in presence of a number of different contaminants. It highlights that the molecular environment around soluble species at the surface is resembling that of a concentrated solution containing this solute. The surface energy is minimized by accommodating the trace species into a local solution like environment. Therefore, at low contaminant levels, the elusive quasi-liquid layer is not extending over larger scales than the hydration shells of solutes present at the surface, and the majority of the ice surface remains ice-like. Whether such hydrated species prefer the ice - air interface or grain boundary remains an open question. In contrast, if solutes may form a stable solution in equilibrium with ice, they form a separate phase. For halides, such brines tend to be excluded to the ice surface, while their surface chemical properties are consistent with the halide - water - ice phase diagram. These features of the contaminated ice surface govern the chemical properties and thus reactivity. When scaled up to the level of snow, the continuously evolving structure of snow becomes important, as it determines in what way the contaminant species are exposed to the interstitial air or the transport processes into and out of the snowpack
10:20 Can detailed oxidation kinetics indicate where reactivity occurs in ice? - Jon Abbatt
Can detailed oxidation kinetics indicate where reactivity occurs in ice?
- Jon Abbatt
10:20 - 10:40
One of the significant challenges to the ice chemistry community is to identify the medium in which reactive chemistry occurs, ie. on a QLL surface, in an associated brine, or in the bulk ice, and how fast it occurs in each medium. This talk will present the results from two reactive systems which help to identify the location of the reactive chemistry. In particular, detailed kinetics will be presented for: i) the heterogeneous oxidation of bromide by gas-phase ozone in both liquid and frozen salt solutions, and ii) the oxidation of succinic acid in liquid and frozen solutions, by photolytically generated hydroxyl radicals. In the case of ozone/bromide, the kinetics indicate that both a surface and bulk phase reaction occur simultaneously with kinetics very similar between the frozen and liquid solutions. This suggests that brine chemistry is dominant. For the case of succinic acid, the unfrozen solution kinetics are substantially faster than for the frozen solutions, suggesting that the reactants are physically separated in the ice.
10:40 short discussion
short discussion
10:40 - 10:55

10:55

10:55 - 11:25

11:25

11:25 - 12:25

12:25

12:25 - 13:25

13:25

13:25 - 14:55

14:55

14:55 - 15:55

15:55 Writing teams can meat seperately
Writing teams can meat seperately
15:55 - 17:55

17:55 Meeting ends: Summary & Deadlines
Meeting ends: Summary & Deadlines
17:55 - 18:25
Wednesday, 8 June 2011
09:00
09:00 - 17:20
Contributions

09:00 Introduction

09:15 Microstructural Modeling of Snow- and Firn Processes - Thomas Kaempfer (AF Colenco Ltd / CRREL)

09:45 Comparative molecular dynamics study of vapor-exposed basal, prismatic and pyramidal surfaces of ice - Martina Roeselova (Institute of Organic Chemistry and Biochemistry ASCR Prague)

10:00 Parameterizing Trace Gas - Ice Interactions: A look into laboratories - Thorsten Bartels-Rausch (Paul Scherrer Institut)

10:15 Discussion: Representing physical and chemical processes on the micro scale in models

11:30 Photolysis rates of nitrate, hydrogen peroxide and nitrite in Arctic and Antarctic snows: A field and modelling study - Martin King (Royal Holloway University of London)

11:45 Investigating the Impact of Snowpack Photodenitrification on Antarctic Atmospheric Chemistry Utilizing Results from a Snowpack Radiative Transfer Model in a Global Chemical Transport Model - Maria Zatko (University of Washington)

12:00 Discussion: Radiative transfer and photolysis rates in snow

13:30 Development of a mechanistic representation of snow-atmosphere exchange of reactive compounds for implementation in large-scale models - Laurens Ganzeveld (1Earth System Sciences - Climate Change group, department of Environmental Sciences, Wageningen University and Research Centre, Wageningen, Netherlands)

14:00 Reactive halogen release from the polar snowpack and the depletion of ozone and mercury in the air: Insights from 1-D (mechanistic) and 3-D (chemical transport) models - Kenjiro Toyota (York University / Environment Canada)

14:15 How different would tropospheric oxidation be over an ice-free Arctic? - Apostolos Voulgarakis (NASA Goddard Institute for Space Studies at Columbia University, New York, USA)

14:30 Discussion: representing processes in the snow in global models

16:00 Summary + Outlook

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