RESEARCH

Our research is in the field of physical chemistry and analytical chemistry of relevance to the atmosphere and atmospheric interfaces (air/water/ice/snow). It focuses on the understanding of selected chemical transformations of organic compounds, as well as the understanding of trace metal pollutants in the atmosphere and at atmosphere/water/snow interfaces. Identifying such atmospheric processes can also be significant in understanding the complexity of air pollution and health hazards including airborne particulate matter (aerosols). The interaction between aerosols and clouds is a significant factor affecting the magnitude of the climate change and is a major research topic recognized by the International Panel on Climate Change (IPCC; 2007). The chemical reactions are studied through state-of-the-art kinetic and photochemical laboratory investigations. We perform highly sensitivity measurements of trace compounds to characterize chains of chemical reactions and nucleation processes, both in the atmosphere and at air/water/snow interfaces. Further research activities include complementary computational and atmospheric chemical modelling of the reaction intermediates in the atmosphere to simulate the complex physical-bio-chemical interactions. During the last five years, we also focus on development of novel green chemistry methods and techniques for removal of pollutants.

The funding for our research has been provided through NSERC, FCAR/FQRNT, CFI, Environment Canada, CSA, CFCAS, and McGill University.

 

 

(I) TRACE METAL CHEMISTRY IN ATMOSPHERE AND ATMOSPHERE-ICE-WATER-SNOW INTERFACES:


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1.1 Kinetic and mechanistic study of oxidation-reduction mechanisms of mercury:

Mercury is a persistent, toxic and bio-accumulative pollutant of global interest. Its main mass in the troposphere is in the form of elemental gas phase mercury. Rapid, near-complete depletion of mercury has been observed during Springtime in the atmospheric boundary layer of frozen marine areas in the Arctic, sub-Arctic and Antarctic locations. It is strongly correlated with ozone depletion. Evidence has indicated that the chemistry involving halogen gases from surface sea-salt is the mechanism of this destruction. Precisely which halogen gases are the main players remained unresolved. Our novel kinetic and mechanistic data on several reaction schemes and multi-scale modeling showed that Br atoms and to lesser extent BrO radicals are the most effective halogens driving mercury oxidation, even by changing the rate coefficients by two folds, accounting for the wide range of discrepancy of the existing literature data on Hg kinetics. The reduction of oxidized mercury deposited in the snow pack back to Hg0, and subsequent diffusion to the atmosphere has also been observed. However, it cannot compensate for the total deposition and thus a net accumulation occurs.

We used a unique global atmospheric mercury model to show that halogen driven mercury depletion events resulting in an increase in the net deposition of mercury to the Arctic relative to scenarios that do not include halogen chemistry. We have also shown evidence for the formation of mercury aerosols upon the oxidation reactions in the course of laboratory experiments and field measurements in the high Arctic. This may impact the extent of bioaccumulation of oxidized mercury. The detailed homogeneous and heterogeneous production and transformation routes for stable Hg(II) and Hg(I) have been investigated in our labs, as well as the impact of phase partitioning of mercury species under different environmental conditions, and the impact of organic mediated reactions. We use several complementary instruments to investigate a given system ranging from high resolution FTIR-Raman, various mass spectrometer techniques (chemical ionization, electron impact, MALDI-TOF, GC/MS), cold-vapour fluoresencence spectroscopy, atomic absorption spectroscopy, to high-resolution transmission electron microscopy. In this manner, we can follow the kinetic and mechanistic study in the gas phase, as well as reactions on aerosols and reactions walls.


1.2 Mercury reactions on surfaces:

Current scientific understanding of either gas or aqueous phase chemical reactions cannot completely predict the fate and transformation of chemical species in the atmosphere. Given the omnipresence of interfaces in nature, it is apparent that reactions occurring at the surfaces need to be taken into account. To this end, surface-selective spectroscopic methods of second harmonic and sum frequency generation will be utilized to investigate both the equilibrium and the dynamic processes occurring at various atmospherically relevant surfaces. Our ongoing research focuses on fundamental studies of reactions on adsorption processes of mercury on model surfaces to provide ultimately the understanding of the impact of surfaces such as snow and ice on mercury transformation and also the understanding of the organic assisted photo-redox mechanisms of oxidized mercury in aerosols or at air/water, and air/snow/ice interfaces.


Selected related publications in this domain:


  1. L. Si and P. A. Ariya, The kinetics and mechanistic studies of photoreduction of selected natural thiols, Chemosphere, in press (2011)
  2. M. Subir, P. A. Ariya, and A. Dastoor, , Fundamental limitations and the importance of trace metal heterogeneous chemistry, Atmospheric Environment, in press (2011)
  3. M. Subir, P. A. Ariya, and A. Dastoor, A Review of the Sources of Uncertainties in Atmospheric Mercury Modeling I. Uncertainties in existing kinetic parameters, Atmospheric Environment, in press (2011).
  4. Parisa A. Ariya, Atmospheric science: Mid-latitude mercury loss, Nature Geoscience, 4, 2011 (doi:10.1038/ngeo1048) (2011)
  5. Graydon Snider and Parisa Ariya, Photo-catalytic oxidation reaction of gaseous mercury over titanium dioxide nanoparticle surfaces, Chemical Physics Letters, 491, 23-28 (2010)
  6. Parisa A. Ariya, Kirk Peterson, Graydon Snider and Marc Amyot, Mercury Chemical transformation in the gas, aqueous and heterogeneous phases: State-of-the art science and uncertainties, book chapter 15, Mercury fate and transport in the global atmosphere, Pirrone and Mason editors,Springer, pp, 459-501, ISBN: gtt v 987-0-387-93957-5 (2009)
  7. G. Snider, F. Raofie, and P. A. Ariya, "Effects of relative humidity and CO(g) on the O-3 initiated oxidation reaction of Hg-O(g): kinetic & product studies". Physical Chemistry-Chemical Physics, 10(36): 5616-5623 (2008)
  8. F. Raofie, G. Snider, and P. A. Ariya, "Reaction of gaseous mercury with molecular iodine, atomic iodine, and iodine oxide radicals - Kinetics, product studies, and atmospheric implications", Canadian Journal of Chemistry, 86(8): 811-820 (2008)
  9. Lin Si and P. A. Ariya, "Reduction of oxidized mercury species by dicarboxylic acids (C2-C4): Kinetics and products studies". Environ. Science and Technology, 42: 14, 5150-5155 (2008)
  10. A. J. Poulain, E. Garcia, M. Amyot, P. G. C. Cambell, F. Raofie, and P. A. Ariya, Mercury speciation and reactivity in the high Arcitc on Cornwallis Island, / Geochemica Cosmochimica Acta/, 71, 3419-3431 (2007)
  11. Poulain A.J., Ni Chadhain S. M., Ariya P. A., Amyot M., Garcia E., Campbell P. G. C., Zylstra G., and Barkay T. 2007. A potential for mercury reduction by microbes in the high Arctic. /Appl. Environ. Microbiol.,/ 73(7): 2230-2238 (2007)
  12. Poulain, A. J.; Garcia, E.; Amyot, M.; Campbell, P. G. C.; Raofie, F.; Ariya, P., Biological and Chemical Redox Transformations of Mercury in Fresh and Salt Waters of the High Arctic during Spring and Summer /A., Environ. Sci. Technol., /41(6); 1883-1888 (2007)
  13. M. A. Engle, M. Sexauer Gustin, S. E. Lindberg, A. W. Gertler. P. A. Ariya, The influence of ozone on atmospheric emissions of gaseous elemental mercury and reactive gaseous mercury from substrates, Atmospheric Environment 39, 7506-7517 (2005)
  14. P. A. Ariya and K. Peterson, Atmospheric Chemical Transformation of Elemental Mercury, Mercury in Environment, chapter 13, Kluwer, Nicolas Pirrone (editor) (2005)
  15. E. Garcia, M. Amyot and P.A. Ariya, "The relationship between DOC photochemistry and mercury redox transformations in aquatic systems of varying humic content", Geochimica et Cosmochimica Acta, 69, 8, 1917-1924 (2005)
  16. E. Garcia, A.J. Poulain, M. Amyot and P.A. Ariya, "Diel variations in photo-induced oxidation of Hg0 in freshwater", Chemosphere, 59(7), 977-982 (2005)
  17. P.A. Ariya, A P. Dastoor, M. Amyot, W.H. Schroeder, L. Barrie, K. Anlauf, F. Raofie, A. Ryzkhov, D. Davignon; J. Lalonde, A. Steffen, The Arctic: A sink for mercury, Tellus B, 56, 5, 397-403 (2004)
  18. M. Amyot, F. Morel and P.A. Ariya, "The effect of surfaces on Hg droplets in environmental compartments", Environmental Science and Technolog, 39, 1, 110-114 (2004)
  19. F. Raofie and P.A. Ariya, "First evidence of stable Hg+1 in aerosols", Environmental Science and Technology, 38(16); 4319-4326 (2004)
  20. B. Paul and P.A. Ariya, "Studies of O3-initiated reaction of gaseous mercury Hg0: kinetics, product studies, and atmospheric implications atmosphere", Physical Chemistry-Chemical Physics, 6, 572-579 (2004)
  21. J.D. Lalonde, M. Amyot, J. Orvoine, F. Morel, J.-C. Auclair and P.A. Ariya, "Photoinduced oxidation of Hg(aq) in the waters from the St. Lawrence estuary", Environmental Science and Technology, 38(2), 508-514 (2004)
  22. F. Raofie and P.A. Ariya, "Mercury aerosols in atmosphere", RMZ- Materials and Geoenvironment, 51: 774-778, (2004)
  23. B. Pal and P.A. Ariya, "Gaseous reactions of atmospheric oxidants with elemental mercury: kinetics, mechanistic, and atmospheric implications", RMZ- Materials and Geoenvironment, 51: 724-28 (2004)
  24. P. A. Ariya, A. F. Khalizov, and A. Gidas, "Reaction of Gaseous Mercury with Atomic and Molecular Halogens: Kinetics, Product Studies, and Atmospheric Implications", Journal of Physical Chemistry A, 106(32), 7310-7320 (2002)

(II) BIOAREOSOLS: MICROPHYSICS, AEROSOL-CLOUD INTERACTIONS, CHEMICAL TRANSFORMATION AND BIOGEOCHEMISTRY:


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2.1 Role of Bio-organic matter on chemistry and physics of the atmosphere:


2.1.1 Bioaerosols ice nucleation:


Bioaerosols, a group of organic aerosols ranging from ~ 10 nm to 100 µm, are airborne particles or large molecules that are either alive, carry living organisms or are released from living organisms (e.g., bacteria, fungi, virus, pollen, cell debris, and biofilms; Fig 1.5). The presence of various types of bioaerosols in indoor air, in the troposphere and even in the stratosphere has long been established. Although most research on bioaerosols has focused on issues related to health hazards, there is a substantial body of work in progress on the importance of bioaerosols as ice nuclei (IN) and cloud condensation nuclei (CCN), incorporating them into the alteration of cloud coverage and hence, global climate. Until a few years ago, we had no particular interest in this domain, but by accident we discovered that bioaerosols are capable of rapid and efficient transformation of organic matter in snow, and possibly in conditions such as in fogs and clouds. In addition to their IN and CCN capability, we provided an original hypothesis, based on our laboratory and field data, on the potential role of bioaerosols; in altering the chemistry of the atmosphere via microbiological degradation in modifying the chemical composition of other organic compounds upon collision or contact, and hence inducing changes in the IN or CCN ability of organics in the atmosphere, and in driving the chemistry (including photochemistry) at environmental interfaces such as the air/snow interface. However, we would like to emphasize that there are more questions than answers regarding the significance (or lack thereof) that bioaerosol physics and chemistry have on climate change, and we have yet to discover many facets of this amazing multidisciplinary domain. Our ongoing and near future laboratory endeavors include ice nucleation studies of bioaerosols in water/snow, on organic aerosols and attached to sulfate and dust particles; the changes of ice nucleation temperature of organic compounds due to biomaterials, the impact of bioaerosols in the snow and production of volatile organic matter upon or in absence of photolysis, and (iv) the impact of biomaterials in triggering ice nucleation and in cloud formation.

Ice nucleation tests on bacteria isolated from snow as well as grown in the lab, in comparison with those of known organic and inorganic aerosols, shed light on the importance of bio-aerosols on cloud processes. Among many snow bacterial isolates in sampling sites from 43-82 N latitudes, several bacterial species, none belonging to Pseudomonas or Erwinia genera, were identified to show an intermediate range of ice nucleation activity. Comparable results were also obtained for molten snow samples and inorganic suspensions (kaolin and montmorillonite) of buffered water solutions. Considering experimental limitations, and drawing from observation in snow samples of a variety of bacterial populations with variable ice nucleation ability, a shift in airborne-species population may significantly alter glaciation processes in clouds.

2.1.2 Modelling study of bioaerosols in cloud formation:

One of the unsolved challenges in cloud microphysics is the rapid formation of exceptionally high ice particle concentrations in warm-based cumulus clouds (cloud base temperatures greater than 0oC) (e.g., Koenigh, 1963; Massop, 1968; Hobbs, 1998; Baker, 2001). Ice particle concentrations can increase from < 0.01 L-1 to more than 100 L-1 in 10 minutes at cloud top temperatures warmer than -10o C. The mechanism which produces ice-particle concentrations two or more orders of magnitude greater than typical concentrations of ice nuclei is not well understood and is therefore difficult to represent in global climate models. In collaboration with Professors Leighton and Yau at McGill, we have developed a novel 1.5-dimensional non-hydrostatic cumulus cloud model with bin-resolved microphysics that includes bioaerosols. Our hypothesis, based on some preliminary modelling results, is that ice multiplication in warm-based convective clouds can in fact be explained by the Hallett-Mossop mechanism (an experimentally driven ice multiplication process describing the collisions of grauples with cloud nuclei). If the most active ice nuclei, such as bioaerosols, especially bacteria act as trigger for this process, the issue of ice multiplication can indeed be regarded as issues of warm-rain initiation and ice nucleation. The large ice crystal concentrations generated in the present simulation are not necessarily limited to cumulus clouds but may also occur in large scale stratiform clouds in which supercooled drizzle drops form as a result of some small-scale convection within them. Cloud optical properties and hence shortwave cloud forcing can thus be influenced by the size distribution and phase of the water. This potential forcing is expected to be non-negligible but yet to be evaluated. If the drizzle-sized supercooled drops and bioaerosol ice nuclei in cloud form will be important, they will influence significantly cloud radiative forcing. Parameterization of these two factors in global climate models will benefit the accurate estimation of climate change. Our results will potentially allow global climate models to provide more adequate simulation of the Earth's radiation budget.


Selected related publications in this domain:


  1. P. A. Ariya,A,B F. Domine,C G. Kos,B,H M. Amyot,D V. Cote,B H. Vali,E T. Lauzier,C W. F. Kuhs,F K. Techmer,F T. HeinrichsG and R. Mortazavi, Snow – a photobiochemical exchange platform for volatile and semi-volatile organic compounds with the atmosphere, Environmental Chemistry. (2010)
  2. Sun, J., P. A. Ariya, H. G. Leighton, and M. K. Yau, The Mystery of Ice Multiplication in Warm-based Precipitating Shallow Cumulus Clouds, Geophys. Res.Lett. (2010)
  3. P.A. Ariya, J. Sun, N.A. Eltouny, E.D. Hudson, C.T. Hayes and Kos,G 'Physical and chemical characterization of bioaerosols - Implications for nucleation processes', International Reviews in Physical Chemistry. (2009)
  4. V. Cote, G. Kos, R. Mortazavi and P. A. Ariya, "Microbial and "de novo" transformation of dicarboxylic acids by three airborne fungi", Science of the Total Environment. (2008)
  5. R. Mortazavi,C.T. Hayes, P.A. Ariya, "Ice nucleation activity of bacteria from snow compared with organic & inorganic substrates", Environmental Chemistry. (2008)
  6. P.A. Ariya and M. Amyot, "Bioaerosols: Impact on physics and chemistry of the atmosphere", Atmospheric Environment. (2004)
  7. P. A. Ariya, O. Nepotchatykh, O. Igntova and M. Amyot, "Microbiological degradation of organic compounds in the atmosphere", Geophysical Research Letters. (2002)

(III) HALOGEN CHEMISTRY:


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3.1 Reactions of atmospheric oxidants with volatile and semi-volatile compounds and intermediates: Kinetic, thermo-chemical and mechanistic studies:

The evidence for halogens such as Cl-atom and Br-atom (and their oxides) reactions, in addition to HO, O3, NO3, rapidly became of key interest to many researchers. These radicals can react rapidly with atmospheric compounds, playing key roles in the degradation and transformation of various chemicals in the troposphere. Br-atoms have also been found to be major players in the destruction of unsaturated compounds and one of the most important greenhouse gases, ozone. Many of these primary and secondary products are toxic to plants and animals, and it is essential that the atmospheric fate of these molecules is determined. The radical addition reactions to carbon-carbon double bonds have been a topic of long-standing interest to us. These reactions normally lead to the formation of carbon-centered radicals, as the π-bond upon interaction with unpaired valence of the approaching radical transforms into new σ-bond and the radical centers at the carbon atom (Figures 1.3 and 1.4). If the radical attacking the alkene is a halogen atom, the addition reaction gives a b--haloaklyl radical. In addition to halogen-alkene reactions, b-haloaklyl radicals can also be formed in radical halogenation of (halo)alkanes, as well as in the thermolysis or photolysis of various halogenated compounds. The importance of b-halolakyl radicals in many chemical processes led to a number of experimental and theoretical studies of their structure and reactivity. The 1,2-halogen migration and its role in the stereoselectivity of the halogenation reactions of various alkanes and alkenes has been given special attention. In order to interpret surprisingly high steroselectivity of the reactions of bromo-substituted radicals, several studies (Goering et al., Thaler, and later Skell and Traynham) proposed, in addition to the classical carbon-centered b-halolakyl radical structure, an alternative bridged structure:

We combine experimental and computational study of the reactions of alkenes with halognes such as bromine atoms.. Effective rate constants k of the gas-phase reactions of several alkenes with halogens at tropospheric conditions are measured and used in combination with the literature data to find a quantitative structure-activity relationship (QSAR) between the lnk and the HOMO energy of the alkene, which holds for all alkenes studied. We have found this method is appropriate except for tri- and tetrachloroethene. To gain insight into possible sources of this irregularity, high-level CASPT2 (including spin-orbit coupling effects) and DFT calculations of structures and stability of bromine atom adducts with ethene and tetrachloroethene have been performed in our labs. We presently investigating the role of stable structure, as well bridged structures to gain insides on pre-reaction, which might exist as a local minimum on the potential energy surface. We also strive to understand the mechanistic differences amongst the reactions of halogenated alkenes.


Selected related publications in this domain:


  1. A. Garib, Q, Timergazin, and P.A. Ariya, "Kinetics and product studies of Cl-atom initiated of selected hydrocarbons in the marine boundary layer", Canadian Journal of Chemistry, 84, 1686-1695 (2006)
  2. Qadir Timerqazin and Parisa A. Ariya, "Kinetics and mechanistic studies of Cl-atom initated reaction of terpenes", Physical Chemistry-Chemical Physics, 3, 3981-3986 (2001)
  3. Sandrine Coquet and Parisa Ariya, The temperature dependence of Cl-atom initiated reactions of selected alkenes under tropospheric conditions, International Journal of Chemical Kinetics, 32, 478-488 (2000)
  4. V. Catoire, P. A. Ariya, H. Niki and G. W. Harris, FTIR study of Cl and Br atom oxidation of trichloroethylene at T = 296?2 K;, International Journal of Chemical Kinetics, 29, 695-704 (1997)
  5. J. Chen, V. Young, P .A. Ariya (Hooshiyar), M. Hurley and H. Niki, FTIR study of the Cl-initiated oxidation of ethylene oxide, J. Phys. Chem, 99, 4071-4077 (1995).
  6. Parisa A. Ariya (Hooshiyar) and Hiromi Niki, Reaction rate of Cl-atoms with a series of C2-C8 alkanes at T = 296 +/- 2 K, Int. J. Chem. Kinetics, 27, 1197-1206 (1995).

(IV) ORGANIC COMPOUNDS/AEROSOLS IN ATMOSPHERE: FUNDAMENTAL LABORATORY & COMPUTATIONAL CHEMISTRY STUDIES:


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Ozonolysis reactions: impact on atmospheric oxidation:

Mechanisms of ozonolysis reactions are very complex and still poorly understood. Our theoretical studies suggested that during the dark seasons, ozonolysis of alkenes are the major sources of HO (the dominant "atmospheric detergent"), H2O2 and RO2 in the atmosphere. This reaction pathway is indeed calculated to be much more important than the "traditional" photochemically initiated reactions during dark seasons. We have also shown that this additional amount of HOx can be major cause of conversion of Sulfur (IV) to Sulfur (VI), a phenomenon which is also so-called "acid-rain" in atmospheric water. Our laboratory studies provided temperature dependence kinetic data set and peroxide yields for over 15 internal and terminal alkene systems and provided structure-reactivity relationships, implemented in atmospheric chemical models. We aimed to obtain a better understanding of the chemical mechanisms for the formation of condensable material from gas phase organic compounds, as well as the chemical composition, reactivity and volatility of the particles formed. Our group addresses these questions from the precursor end. We study kinetics and mechanisms of the oxidation reactions by using spectroscopic and chromatographic techniques to follow the changes in concentration of the precursor compounds and major intermediates. We have indeed developed a moving solid phase microextraction unit to the long path FTIR, used periodically at different reaction steps for better analysis of organic particles, along with a multi-stage aerosol impactor. The experiments are supported by theoretical studies of possible intermediate species. The results are used to develop parameterizations of oxidation mechanisms for use in computer models. Another area of our ongoing research includes understanding the ozononlysis reactions of alkenes and its subsequent reactions with water and water dimer. The ozone-initiated oxidation of alkenes is among the few reactions of closed shell molecules (non-radicals) leading to the formation of free radical species in the atmosphere. Criegee intermediate (CI) was postulated as intermediate in the ozonolysis reactions of alkenes in the liquid and gas phases (Eq. 1).

We have determined the temperature dependence kinetics for some key ozonolysis reactions and developed structure-reactivity relationship for predictive use. We have also performed theoretical studies including the reactions of parent and substituted Criegee intermediates with water and the water dimer. According to our calculations, the most favourable route is the formation of hydroxyalkyl hydrogen peroxide as the result of the reactions of CI with the water dimer. Our ongoing and near future research entails theoretical investigations of the reactions of CI with water clusters, and laboratory mechanistic studies of alkenes and ozone at different environmental conditions, including relative humidity and temperature. We also perform reactions reactions at surfaces (e.g., Hung and Ariya, J. Phys. Chem., 2007). There is no overlap with the projects in the enclosed proposal.


Selected related publications in this domain:


  1. E. D. Hudson, and P. A. Ariya, Measurements of Non-Methane Hydrocarbons, DOC in Surface Ocean Waters, and aerosols over the Nordic Seas during Polarstern cruise ARK-XX/1, Chemosphere, DOI:10.1016/j./chemosphere./2007.04.056 (2007)
  2. H. M. Hung, P. A. Ariya, The Oxidation of Oleic Acid and Oleic Acid/Sodium Chloride(aq) Mixture Droplets with Ozone: the Changes of Hygroscopicity and the Role of Secondary Reactions, /J. Phys. Chem. A.,/ 111(4); 620-632 (2007)
  3. Ryzhkov, Andrew B. and Ariya, Parisa A., A theoretical study of the reactions of carbonyl oxide with water in atmosphere: the role of water dimer. Chemical Physics Letters, 367(3-4), 423-429 (2003).
  4. E. Avzyanova, P. A. Ariya, Kinetic studies of ozonolysis of selected terminal and internal alkenes: evaluation of HO yield, International Journal of Chemical Kinetics, Volume 34, Issue 12, 678-684 (2002).
  5. P. A. Ariya, R. Sander and P. J. Crutzen, Significance of HOx formation in the winter-time: A modelling studies, Journal of Geophysical Research, 105, 17721-17738 (2000).

(V) DEVELOPMENT OF NOVEL ANALYTICAL TECHNIQUES FOR ATMOSPHERIC AND INTERFACIAL CHEMICAL STUDIES:


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5.1 Development of mercury chemical speciation:

Oxidized mercury in the atmosphere is a crucial link between gaseous elemental mercury emitted from human activity and mercury pollution in remote aquatic environments. The chemical forms of oxidized mercury formed from elemental mercury in the atmosphere will determine to a large part the rate at which mercury is removed from the atmosphere to natural waters. Current methods for the detection of oxidized mercury in the atmosphere provide only information concerning the total amount of mercury present in the atmosphere as oxidized mercury, not the chemical forms of oxidized mercury that are present. At McGill, we have recently developed a technique to directly measure oxidized mercury. Further research will focus on refinement of the developed technique and its field implementation, with the focus on comparison of urban, remote continental and marine environments.

5.2 Ocean-atmosphere coupling of semi-)volatile organic matter and dissolved organic matter:

Snow/air and water/air interfaces are fascinating locations for chemical reactions. The nature of these interfaces and their roles in the exchange of chemicals, organic compounds in particular, are not well understood. Low molecular weight aldehydes and ketones in the surface oceans are produced by dissolved organic matter photochemistry or by biology, and can be transferred to the atmosphere, affecting its oxidative capacity. They thus link the organic carbon biogeochemistry of the atmosphere and the oceans. We have developed and optimized a mobile, economical and facile method, which allows for the simultaneous quantification of 23 C1 – C9 low molecular weight aldehydes and ketones in seawater, a well as in the gas phase. Detection limits range from 0.01 nM to 23.5 nM, depending on the compound, with sub-nanomolar detection limits achieved for most compounds in sea water, and we were involved in calculating the fluxes between atmosphere and Atlantic ocean surfaces. We have also developed methodology of quantification volatile and semi-volatile organic matter in snow that were tested in several field sites in the province of Quebec as well as two Arctic sites of Alert and Barrow (OASIS 2009). We were invited to several field measurement campaigns in the North Atlantic and the high Arctic (SOLAS and POLARSTERN), one in which we participated, and the other performed by two graduate students in our group. A substantial portion of the organic compounds in the snow is of biogenic origins, and we intend to learn more in this area, as our preliminary results are very promising and indicate that snow is indeed a photo-biochemical platform for release of volatile organic compounds.


Selected related publications in this domain:


  1. E. Hudson, P. A. Ariya, and Y. Gelinas, A method for the simultaneous quantification of 23 C1-C9 trace aldehydes and ketones in seawater, Environmental Chemistry (2011) in press
  2. P. A. Ariya,A,B F. Domine,C G. Kos,B,H M. Amyot,D V. Cote,B H. Vali,E T. Lauzier,C W. F. Kuhs,F K. Techmer,F T. HeinrichsG and R. Mortazavi, Snow – a photobiochemical exchange platform for volatile and semi-volatile organic compounds with the atmosphere, Environmental Chemistry (2010)
  3. G. Kos and P. A. Ariya, Volatile organic compounds in snow in the Quebec-Windsor Corridor JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 115, D01302, doi:10.1029/2009JD012391 (2010)
  4. E. D. Hudson, K. Okuda and P. A. Ariya, Determination of Acetone in Seawater Using Derivatization-Solid Phase Microextraction/, Analytical and Bioanalytical Chemistry/, DOI 10.1007/S0021-6-007-132X (2007)
  5. E. D. Hudson, and P. A. Ariya, Measurements of Non-Methane Hydrocarbons, DOC in Surface Ocean Waters, and aerosols over the Nordic Seas during Polarstern cruise ARK-XX/1, Chemosphere, DOI:10.1016/j./chemosphere./2007.04.056 (2007)
  6. A. B. Ryzhkov and P. A. Ariya, The importance of water clusters (H2O)n (n=2..4) in the reaction of Criegee intermediate with water in the atmosphere, Chemical Physics Letter, 419, 479-485 (2006)

(VI) DEVELOPMENT OF NOVEL "GREEN CHEMISTRY" TECHNIQUES FOR AIR AND WATER POLLUTION REMEDIATION:


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6.1 Development of technology for air pollutant reduction and recycling:

Air pollution is a major environmental challenge causing tangible health, economic and climatic effects, particularly in the developing countries where emissions are increasingly rapid. Clearly the best way to pursue pollution remediation is to reduce pollution emissions preferably by using less energy or by reducing pollutants at their source, however there mains major technological challenge of removing atmospheric pollutants, both indoor and outdoor, without causing adverse effects such as the production of CO2 and aerosols. We developed a novel technology and methods that enables us to use a suite of natural materials for removal of air pollutants, and the interfaces that we have made are recyclable using entirely the renewable energy. We have developed prototype for removal of trace metals such as trace pollutants such as mercury, as well as NOx, SOx, VOC, bioaerosols. Our current research is involved in development of green chemistry techniques and methods for CO2, and wide range of co-pollutants from atmosphere, as well as aquatic systems using natural interfaces. We aim to discern physical and chemical processes involved in the uptake reactions at molecular levels, and upscale our technique for industrial application. We plan to perform life cycle analysis not only at the source but also perform simulated environmental studies to evaluate the benign nature of these innovations to the Earth ecosystem.


Selected related publications in this domain:


  1. Graydon Snider and Parisa Ariya, Photo-catalytic oxidation reaction of gaseous mercury over titanium dioxide nanoparticle surfaces, Chemical Physics Letters, 491, 23-28 (2010)