A negative feedback between anthropogenic ozone pollution and enhanced ocean emissions of iodine

Naturally emitted from the oceans, iodine compounds efficiently destroy atmospheric ozone and reduce its positive radiative forcing effects in the troposphere. Emissions of inorganic iodine have been experimentally shown to depend on the deposition to the oceans of tropospheric ozone, whose concentrations have significantly increased since 1850 as a result of human activities. A chemistry-climate model is used herein to quantify the current ocean emissions of inorganic iodine and assess the impact that the anthropogenic increase in tropospheric ozone has had on the natural cycle of iodine in the marine environment since pre-industrial times. Our results indicate that the human-driven enhancement of tropospheric ozone has doubled the oceanic inorganic iodine emissions following the reaction of ozone with iodide at the sea surface. The consequent build-up of atmospheric iodine, with maximum enhancements of up to 70% with respect to pre-industrial times in continental pollution outflow regions, has in turn accelerated the ozone chemical loss over the oceans with strong spatial patterns. We suggest that this ocean-atmosphere interaction represents a negative geochemical feedback loop by which current ocean emissions of iodine act as a natural buffer for ozone pollution and its radiative forcing in the global marine environment.Fil: Prados Roman, C.. Consejo Superior de Investigaciones Científicas. Instituto de Química Física; EspañaFil: Cuevas, Carlos Alberto. Consejo Superior de Investigaciones Científicas. Instituto de Química Física; EspañaFil: Fernandez, Rafael Pedro. Consejo Superior de Investigaciones Científicas. Instituto de Química Física; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; ArgentinaFil: Kinnison, Douglas E.. National Center For Atmospheric Research. Amospheric Chemistry División; Estados UnidosFil: Lamarque, Jean Francoise. National Center For Atmospheric Research. Amospheric Chemistry División; Estados UnidosFil: Saiz-lopez, Alfonso. Consejo Superior de Investigaciones Científicas. Instituto de Química Física; Españ

Seasonal impact of biogenic very short-lived bromocarbons on lowermost stratospheric ozone between 60° N and 60° S during the 21st century

Biogenic very short-lived bromocarbons (VSLBr) currently represent ∼25 % of the total stratospheric bromine loading. Owing to their much shorter lifetime compared to anthropogenic long-lived bromine (e.g. halons) and chlorine (e.g. chlorofluorocarbons), the impact of VSLBr on ozone peaks in the lowermost stratosphere, which is a key climatic and radiative atmospheric region. Here we present a modelling study of the evolution of stratospheric ozone and its chemical loss within the tropics and at mid-latitudes during the 21st century. Two different experiments are explored: considering and neglecting the additional stratospheric injection of 5 ppt biogenic bromine naturally released from the ocean. Our analysis shows that the inclusion of VSLBr results in a realistic stratospheric bromine loading and improves the agreement between the model and satellite observations of the total ozone column (TOC) for the 1980?2015 period at mid-latitudes. We show that the overall ozone response to VSLBr at mid-latitudes follows the stratospheric evolution of long-lived inorganic chlorine and bromine throughout the 21st century. Additional ozone loss due to VSLBr is maximized during the present-day period (1990?2010), with TOC differences of −8 DU (−3 %) and −5.5 DU (−2 %) for the Southern Hemisphere and Northern Hemisphere mid-latitudes (SH-MLs and NH-MLs), respectively. Moreover, the projected TOC differences at the end of the 21st century are ∼50 % lower than the values found for the present-day period.We find that seasonal VSLBr impact on lowermost stratospheric ozone at mid-latitude is influenced by the seasonality of the heterogeneous inorganic-chlorine reactivation processes on ice crystals. Indeed, due to the more efficient reactivation of chlorine reservoirs (mainly ClONO2 and HCl) within the colder SH-ML lowermost stratosphere, the seasonal VSLBr impact shows a small but persistent hemispheric asymmetry through the whole modelled period. Our results indicate that, although the overall VSLBr-driven ozone destruction is greatest during spring, the halogen-mediated (Halogx-Loss) ozone loss cycle in the mid-latitude lowermost stratosphere during winter is comparatively more efficient than the HOx cycle with respect to other seasons. Indeed, when VSLBr are considered, Halogx-Loss dominates wintertime lowermost stratospheric ozone loss at SH-MLs between 1985 and 2020, with a contribution of inter-halogen ClOx?BrOx cycles to Halogx-Loss of ∼50 %.Within the tropics, a small (<−2.5 DU) and relatively constant (∼−1 %) ozone depletion mediated by VSLBr is closely related to their fixed emissions throughout the modelled period. By including the VSLBr sources, the seasonal Halogx-Loss contribution to lowermost stratospheric ozone loss is practically dominated by the BrOx cycle, reflecting the low sensitivity of very short-lived (VSL) bromine to background halogen abundances to drive tropical stratospheric ozone depletion. We conclude that the link between biogenic bromine sources and seasonal changes in heterogeneous chlorine reactivation is a key feature for future projections of mid-latitude lowermost stratospheric ozone during the 21st century.Fil: Barrera, Javier Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Interdisciplinario de Ciencias Básicas. - Universidad Nacional de Cuyo. Instituto Interdisciplinario de Ciencias Básicas; ArgentinaFil: Fernandez, Rafael Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Interdisciplinario de Ciencias Básicas. - Universidad Nacional de Cuyo. Instituto Interdisciplinario de Ciencias Básicas; Argentina. Consejo Superior de Investigaciones Científicas; España. Universidad Tecnológica Nacional; ArgentinaFil: Iglesias Suarez, Fernando. Consejo Superior de Investigaciones Científicas; EspañaFil: Cuevas, Carlos Alberto. Consejo Superior de Investigaciones Científicas; EspañaFil: Lamarque, Jean Francois. National Center for Atmospheric Research; Estados UnidosFil: Saiz-lopez, Alfonso. Consejo Superior de Investigaciones Científicas; Españ

Modelling the Inorganic Bromine Partitioning in the Tropical Tropopause over the Pacific Ocean

The stratospheric inorganic bromine burden (Bry) arising from the degradation of brominated very short-lived organic substances (VSL org ), and its partitioning between reactive and reservoir species, is needed for a comprehensive assessment of the ozone depletion potential of brominated trace gases. Here we present modelled inorganic bromine abundances over the Pacific tropical tropopause based on aircraft observations of VSL org of two campaigns of the Airborne Tropical TRopopause EXperiment (ATTREX 2013 carried out over eastern Pacific and ATTREX 2014 carried out over the western Pacific) and chemistry-climate simulations (along ATTREX flight tracks) using the specific meteorology prevailing. Using the Community Atmosphere Model with Chemistry (CAM-Chem), we model that BrO and Br are the daytime dominant species. Integrated across all ATTREX flights BrO represents ~ 43 % and 48 % of daytime Bry abundance at 17 km over the Western and Eastern Pacific, respectively. The results also show zones where Br/BrO >1 depending on the solar zenith angle (SZA), ozone concentration and temperature. On the other hand, BrCl and BrONO 2 were found to be the dominant night-time species with ~ 61% and 56 % of abundance at 17 km over the Western and Eastern Pacific, respectively. The western-to-eastern differences in the partitioning of inorganic bromine are explained by different abundances of ozone (O3), nitrogen dioxide (NO2) , and total inorganic chlorine (Cly).Fil: Navarro, María A.. University of Miami; Estados UnidosFil: Saiz-lopez, Alfonso. Consejo Superior de Investigaciones Científicas. Instituto de Química Física; EspañaFil: Cuevas, Carlos Alberto. Consejo Superior de Investigaciones Científicas. Instituto de Química Física; EspañaFil: Fernandez, Rafael Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; Argentina. Universidad Tecnologica Nacional. Facultad Regional Mendoza. Secretaría de Ciencia, Tecnología y Postgrado; ArgentinaFil: Atlas, Elliot. University of Miami; Estados UnidosFil: Rodriguez Lloeveras, Xavier. Consejo Superior de Investigaciones Científicas. Instituto de Química Física; EspañaFil: Kinnison, Douglas E.. National Center For Atmospheric Research. Amospheric Chemistry División; Estados UnidosFil: Lamarque, Jean Francois. National Center For Atmospheric Research. Amospheric Chemistry División; Estados UnidosFil: Tilmes, Simone. National Center For Atmospheric Research. Amospheric Chemistry División; Estados UnidosFil: Thornberry, Troy. State University of Colorado at Boulder; Estados Unidos. Earth System Research Laboratory; Estados UnidosFil: Rollins, Andrew. State University of Colorado at Boulder; Estados Unidos. Earth System Research Laboratory; Estados UnidosFil: Elkins, James W.. Earth System Research Laboratory; Estados UnidosFil: Hintsa, Eric J.. State University of Colorado at Boulder; Estados Unidos. Earth System Research Laboratory; Estados UnidosFil: Moore, Fred L.. State University of Colorado at Boulder; Estados Unidos. Earth System Research Laboratory; Estados Unido

Détermination expérimentale des émissions gazeuses de trois espèces végétales potentiellement impliquées dans les feux de forêt accélérés

La plupart des espèces végétales impliquées dans les feux de forêt produisent et émettent des composés organiques volatils (COV). Ces gaz ont des limites inférieures d’inflammabilité de l’ordre de 1 % volumique dans l’air et sont donc fortement inflammables. Les modèles physiques de propagation des feux de forêt n’intègrent pas jusqu’à présent la combustion de ces composés et l’objectif de cette étude est de fournir des données expérimentales afin d’améliorer ces modèles pour mieux prévoir et contrôler les incendies. L’accent est mis sur un phénomène particulièrement dangereux, les feux de forêts accélérés. Il a en effet été noté dans la littérature que sous certaines conditions (de topographie, d’humidité, etc.) les feux de forêt peuvent se comporter de manière surprenante, passant soudainement d’un comportement (vitesse de propagation et énergie dégagée) modéré à un comportement « explosif ». Une hypothèse qualifiée de thermochimique a été proposée pour expliquer ces phénomènes : les COV émis par les plantes (mélangés ou non avec les gaz de pyrolyse) pourraient s’accumuler près du sol en concentration suffisante pour former un prémélange inflammable avec l’air et ainsi entrainer l’accélération du feu. Il existe dans la littérature des données sur les émissions gazeuses des végétaux à température ambiante mais très peu sur les émissions en fonction de la température. Trois espèces typiques des régions méditerranéennes et correspondant à différentes hauteurs du couvert végétal sont étudiées entre 343 et 453 K : Thymus vulgaris, Rosmarinus officinalis et Pinus pinea. Les émissions sont étudiées à l’aide d’un pyrolyseur flash relié à un chromatographe en phase gazeuse couplé à un spectromètre de masse. Les résultats sont discutés et comparés à ceux de la littérature à température ambiante

Injection of iodine to the stratosphere

We report a new estimation of the injection of iodine into the stratosphere based on novel daytime (solar zenith angle < 45°) aircraft observations in the tropical tropopause layer and a global atmospheric model with the most recent knowledge about iodine photochemistry. The results indicate that significant levels of total reactive iodine (0.25-0.7 parts per trillion by volume), between 2 and 5 times larger than the accepted upper limits, can be injected into the stratosphere via tropical convective outflow. At these iodine levels, modeled iodine catalytic cycles account for up to 30% of the contemporary ozone loss in the tropical lower stratosphere and can exert a stratospheric ozone depletion potential equivalent to, or even larger than, that of very short-lived bromocarbons. Therefore, we suggest that iodine sources and chemistry need to be considered in assessments of the historical and future evolution of the stratospheric ozone layer.Fil: Saiz López, Alfonso. Consejo Superior de Investigaciones Científicas. Instituto de Química Física; España. National Center For Atmospheric Research. Amospheric Chemistry División; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Baidar, S.. Cooperative Institute For Research In Environmental Science; Estados Unidos. State University of Colorado at Boulder; Estados UnidosFil: Cuevas, Carlos Alberto. Consejo Superior de Investigaciones Científicas. Instituto de Química Física; EspañaFil: Koening, T. K.. State University of Colorado at Boulder; Estados UnidosFil: Fernandez, Rafael Pedro. Consejo Superior de Investigaciones Científicas. Instituto de Química Física; España. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Dix, Barbara. State University of Colorado at Boulder; Estados UnidosFil: Douglas E. KINNISON. National Center For Atmospheric Research. Amospheric Chemistry División; Estados UnidosFil: Jean-Francoise LAMARQUE. National Center For Atmospheric Research. Amospheric Chemistry División; Estados UnidosFil: Xavier Rodriguez-Lloeveras. Consejo Superior de Investigaciones Científicas. Instituto de Química Física; EspañaFil: Campos, T.L.. National Center For Atmospheric Research. Amospheric Chemistry División; Estados UnidosFil: Volkamer, Rainer. Cooperative Institute For Research In Environmental Science; Estados Unidos. State University of Colorado at Boulder; Estados Unido

CAM6-chem with very short-lived halogen chemistry: evaluation with the whole air sampler aircraft data from multiple seasons and locations

A new version of the Community Atmosphere Model with chemistry (CAM6-chem) has recently been released to the atmospheric science community (June 2018). CAM6-chem has updated boundary layer processes, shallow convection and liquid cloud macrophysics, and two-moment cloud microphysics with prognostic cloud mass andconcentration. A 4-mode prognostic aerosol representation (MAM4) has been added that includes a representation of dust, sea-salt black carbon, organic carbon, and sulfate in three size categories (Gettelman et al., 2019). CAM6-Chem has a detailed representation of both tropospheric and stratospheric chemistry. The tropospheric chemistry includes updates to the representation the organic nitrates, isoprene oxidization, and the speciation of the aromaticand terpenes (Emmons et al., 2019). This mechanism also includes a comprehensive secondary organic aerosol parameterization based on the Volatility Basic Set (VBS) model framework (Hodzic et al. 2016; Tilmes et al., 2019). The stratospheric halogen chemistry represents the distribution of CH3Cl, CFCs, HCFCs, CH3Br, and halons (Kinnison et al., 2007). For this study, the emissions, wet and dry depositions, and chemical processes that represent Very Short-Lived Halogens (VSLH) were added (e.g., Saiz-Lopez et al., 2016). Evaluation of the organic VSLH distributions are to compare with trace gas measurements collected during seven field campaigns, two withmultiple deployments, to evaluate the model performance over multiple years. The campaigns include HIPPO (2009-2011) pole to pole observations in the Pacific on the NSF/NCAR GV over multiple seasons; SEAC4RS (Aug./Sept., 2013) in the central and southern U.S. and western Gulf of Mexico on the NASA ER-2 and DC8; ATTREX (2011-2015) on the NASA Global Hawk over multiple seasons and locations; CONTRAST (Jan/Feb, 2014) in the western Pacific on the NSF/NCAR GV; VIRGAS (Oct., 2015) in the south central US and western Gulf of Mexico on the NASA WB-57; ORCAS (Jan/Feb, 2016) over the southern ocean on the NSF/NCAR GV; and POSIDON (Oct, 2016) in the western Pacific on the NASA WB-57. The model was ?nudged? to NASA Modern-Era Retrospective analysis for Research and Applications, version 2 meteorological fields to represent the synoptic meteorology for each mission. The analysis will focus on along the flight tracks comparisons with the model and will also examine comparisons of vertical distributions and various tracer-tracer correlations. Implications of this new model version on estimated input of inorganic bromine and iodine into the lower stratosphere will be discussed.Fil: Kinnisson, Douglas E.. National Center for Atmospheric Research; Estados UnidosFil: Saiz Lopez, Alfonso. Consejo Superior de Investigaciones Científicas. Instituto de Química Física "Rocasolano"; EspañaFil: Cuevas, Carlos Alberto. Consejo Superior de Investigaciones Científicas. Instituto de Química Física "Rocasolano"; EspañaFil: Fernandez, Rafael Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Exactas y Naturales; Argentina. Universidad Tecnológica Nacional; ArgentinaFil: Lamarque, Jean Francoise. National Center for Atmospheric Research; Estados UnidosFil: Tilmes, Simone. National Center for Atmospheric Research; Estados UnidosFil: Emmons, Louisa K.. National Center for Atmospheric Research; Estados UnidosFil: Hodzic, Alma. National Center for Atmospheric Research; Estados UnidosFil: Wang, Siyuan. National Center for Atmospheric Research; Estados UnidosFil: Schauffler, Sue M.. National Center for Atmospheric Research; Estados UnidosFil: Navarro, María. University Of Miami. Rosenstiel School Of Marine Atmospheric Science; Estados UnidosFil: Atlas, Elliot. University Of Miami. Rosenstiel School Of Marine Atmospheric Science; Estados UnidosEGU General Assembly 2019VienaAustriaEuropean Geociences Unio

Sooting Behaviour Dynamics of a Non-Bouyant Laminar Diffusion Flame

Local soot concentrations in non-buoyant laminar diffusion flames have been demonstrated to be the outcome of two competitive processes, soot formation and soot oxidation. It was first believed that soot formation was the controlling mechanism and thus soot volume fractions could be scaled with a global residence time. Later studies showed that this is not necessarily the case and the local ratio of the soot formation and oxidation residence times is the prime variable controlling the ultimate local soot volume fractions. This ratio is a strong function of geometry and flow field, thus a very difficult variable to properly quantify. This study presents a series of microgravity, low oxidizer flow velocity, experiments where soot volume fraction measurements have been conducted on a laminar, flat plate boundary layer type diffusion flame. The objective of the study is to determine if the above observations apply to this type of diffusion flames. The fuel is ethylene and is injected through a flat plate porous burner into an oxidizer flowing parallel to the burner surface. The oxidizer consists of different mixtures of oxygen and nitrogen, flowing at different velocities. These experiments have been complemented with numerical simulations that emphasize resolution of the flow field to simulate the trajectory of soot particles and to track their history from inception to oxidation. The results validate that local soot volume fractions are a function of the local formation and oxidation residence times and are not necessarily a function of the global residence time. For this particular geometry, an increase in oxidizer velocity leads to local acceleration that reduce the oxidation residence time leading to higher soot concentrations. It was also observed that the flames become longer as the flow velocity is increased in contrast with the reversed trend observed in flames at higher flow velocities. This result is important because it seems to indicate the presence of a maximum in the flame length and luminosity below those encountered in natural convection. The result would have implications for fire safety in spacecrafts since the ambient gas velocities are below those observed in natural convection, and longer and more luminous flames represent a higher hazard

R2 prime (R2') magnetic resonance imaging for post-myocardial infarction intramyocardial haemorrhage quantification.

To assess whether R2* is more accurate than T2* for the detection of intramyocardial haemorrhage (IMH) and to evaluate whether T2' (or R2') is less affected by oedema than T2* (R2*), and thus more suitable for the accurate identification of post-myocardial infarction (MI) IMH. Reperfused anterior MI was performed in 20 pigs, which were sacrificed at 120 min, 24 h, 4 days, and 7 days. At each time point, cardiac magnetic resonance (CMR) T2- and T2*-mapping scans were recorded, and myocardial tissue samples were collected to quantify IMH and myocardial water content. After normalization by the number of red blood cells in remote tissue, histological IMH increased 5.2-fold, 10.7-fold, and 4.1-fold at Days 1, 4, and 7, respectively. The presence of IMH was correlated more strongly with R2* (r = 0.69; P = 0.013) than with T2* (r = -0.50; P = 0.085). The correlation with IMH was even stronger for R2' (r = 0.72; P = 0.008). For myocardial oedema, the correlation was stronger for R2* (r = -0.63; P = 0.029) than for R2' (r = -0.50; P = 0.100). Multivariate linear regressions confirmed that R2* values were significantly explained by both IMH and oedema, whereas R2' values were mostly explained by histological IMH (P = 0.024) and were little influenced by myocardial oedema (P = 0.262). Using CMR mapping with histological validation in a pig model of reperfused MI, R2'more accurately detected IMH and was less influenced by oedema than R2* (and T2*). Further studies are needed to elucidate whether R2' is also better suited for the characterization of post-MI IMH in the clinical setting.This study was partially supported by a competitive grant from the Carlos III Institute of Health-Fondo de Investigacion Sanitaria and the European Regional Development Fund (ERDF/FEDER) (PI16/02110), the Spanish Ministry of Science, Innovation and Universities (MICIU), ERDF/FEDER SAF2013-49663-EXP, by the Comunidad de Madrid (S2017/BMD-3867 RENIM-CM) and cofunded with European structural and investment funds. This study forms part of a Master Research Agreement between the CNIC and Philips Healthcare. This research program is part of an institutional agreement between FIIS Fundacion Jimenez Diaz and the CNIC. The CNIC is supported by the Ministry of Science, Innovation and Universities MICIU the Instituto de Salud Carlos III (ISCiii), and the Pro CNIC Foundation, and is a Severo Ochoa Center of Excellence (award SEV-2015-0505). X.R. has received support from the DYSEC-CNIC CARDIOJOVEN fellowship program. R.F.-J. is a recipient of funding from the European Union Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie (Agreement No. 707642).S

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Antarctic ozone hole modifies iodine geochemistry on the Antarctic Plateau

Polar stratospheric ozone has decreased since the 1970s due to anthropogenic emissions of chlorofluorocarbons and halons, resulting in the formation of an ozone hole over Antarctica. The effects of the ozone hole and the associated increase in incoming UV radiation on terrestrial and marine ecosystems are well established; however, the impact on geochemical cycles of ice photoactive elements, such as iodine, remains mostly unexplored. Here, we present the first iodine record from the inner Antarctic Plateau (Dome C) that covers approximately the last 212 years (1800-2012 CE). Our results show that the iodine concentration in ice remained constant during the pre-ozone hole period (1800-1974 CE) but has declined twofold since the onset of the ozone hole era (~1975 CE), closely tracking the total ozone evolution over Antarctica. Based on ice core observations, laboratory measurements and chemistry-climate model simulations, we propose that the iodine decrease since ~1975 is caused by enhanced iodine re-emission from snowpack due to the ozone hole-driven increase in UV radiation reaching the Antarctic Plateau. These findings suggest the potential for ice core iodine records from the inner Antarctic Plateau to be as an archive for past stratospheric ozone trends.Fil: Spolaor, Andrea. Consiglio Nazionale Delle Ricerche. Istituto Di Scienze Polari.; Italia. Universita' Ca' Foscari Di Venezia; ItaliaFil: Burgay, François. Universita' Ca' Foscari Di Venezia; Italia. Paul Scherrer Institute; SuizaFil: Fernandez, Rafael Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Interdisciplinario de Ciencias Básicas. - Universidad Nacional de Cuyo. Instituto Interdisciplinario de Ciencias Básicas; ArgentinaFil: Turetta, Clara. Consiglio Nazionale Delle Ricerche. Istituto Di Scienze Polari.; Italia. Universita' Ca' Foscari Di Venezia; ItaliaFil: Cuevas, Carlos A.. Consejo Superior de Investigaciones Científicas. Instituto de Química Física; EspañaFil: Kim, Kitae. Korea Polar Research Institute; Corea del SurFil: Kinnison, Douglas E.. National Center for Atmospheric Research; Estados UnidosFil: Lamarque, Jean-François. National Center for Atmospheric Research; Estados UnidosFil: de Blasi, Fabrizio. Consiglio Nazionale Delle Ricerche. Istituto Di Scienze Polari.; Italia. Universita' Ca' Foscari Di Venezia; ItaliaFil: Barbaro, Elena. Consiglio Nazionale Delle Ricerche. Istituto Di Scienze Polari.; Italia. Universita' Ca' Foscari Di Venezia; ItaliaFil: Corella, Juan Pablo. Consejo Superior de Investigaciones Científicas. Instituto de Química Física; EspañaFil: Vallelonga, Paul. Universidad de Copenhagen; Dinamarca. University of Western Australia; AustraliaFil: Frezzotti, Massimo. Università Roma Tre Iii. Dipartimento Di Scienze.; ItaliaFil: Barbante, Carlo. Consiglio Nazionale Delle Ricerche. Istituto Di Scienze Polari.; Italia. Universita' Ca' Foscari Di Venezia; ItaliaFil: Saiz López, Alfonso. Consejo Superior de Investigaciones Científicas. Instituto de Química Física; Españ