The aim of this collaborative project was to improve our understanding of the atmospheric chemistry and impacts of halogens (chlorine, bromine, and iodine) released to the atmosphere in the Arctic.  We conducted a field measurements and modeling study of the atmospheric chemistry involving halogen atoms in the Arctic, at Utqiaġvik (formerly Barrow), AK.  The field measurement campaign was conducted in winter/spring of 2016, at a site on the tundra of the Alaska North Slope.  We conducted first-ever measurements of numerous halogen-containing species, along with ozone, and meteorological parameters, to enable us to assess the impact of halogen chemistry on ozone and other important atmospheric species.  Using new methods in chemical ionization mass spectrometry, we conducted the first ever measurements of molecular iodine (I₂), and used a photochemical model to show that the iodine atoms produced from the photolysis of I₂ has a significant impact on the rate of ozone depletion at the surface in the Arctic.  We found this to be the case of I₂ concentrations as low as 0.3 parts-per-trillion.  Through experiments involving irradiation of the snowpack with sunlight and artificial lights, we showed that the molecular halogens Cl₂, Br₂, BrCl, and I₂ can all be produced photochemically in the snowpack, followed by release of these species into the overlying atmosphere, where they photolyze to significantly impact atmospheric composition.  We also quantified snowpack production fluxes for both Cl₂ and Br₂.  Through photochemical modeling, we showed the importance of ClONO₂, Cl₂, and BrONO₂ in the production of Cl₂, BrCl, and Br₂, respectively.  We conducted the first direct measurements of bromine atoms in the troposphere, explaining quantitatively the loss of ozone and elemental mercury in the Arctic near-surface atmosphere. In addition, we showed enhanced chlorine chemistry under polluted NO_x conditions, including oil field influence, with the first Arctic measurements of ClNO₂, HO₂NO₂, and N₂O₅; this further shows the influence of Arctic development on atmospheric composition.  A new 1-D model to study the vertical scale influence of this chemistry was developed, and several manuscripts have been prepared and submitted. Research findings have been shared with the scientific community through presentations at local, regional, national, and international conferences and through invited seminars. Research-based outreach activities were developed through the Univ. of Michigan Museum of Natural History Science Communication Fellows Program. Outreach focused on underrepresented groups, including through the FEMMES (Females Excelling More in Math, Engineering and the Sciences) program. Pratt developed a general chemistry laboratory course involving a semester-long authentic research experience involving Arctic snow sample analysis using samples collected by first-year undergraduate students in Utqiaġvik during our 2016 fieldwork.  Pratt extended this curriculum development to the high school level through a high school teacher workshop. Fuentes created 2 new lectures for courses in Air Chemistry and Micrometeorology.  Pratt created and gave three lectures at the 2017 Connaught Summer Institute in Arctic Science: Atmosphere, Cryosphere, and Climate in Ontario, Canada. The PIs gave a radio interview for KBRW, serving the northern Alaska villages. The project involved 1 postdoctoral fellow, 4 PhD students (3 dissertations), 1 MS student, and 5 undergraduate students, with the PhD students gaining both fieldwork and modeling experience.  Writer Peter Lourie went to Utqiaġvik to work with 5^th grade teacher Lynn DeFilippo (Fred Ipalook Elem. School) and Leslie Pierce (outreach coordinator, Wildlife Management, North Slope Borough) to engage students in the development of multimedia projects.  Final data/metadata are being archived through the NSF Arctic Data Center.

Last Modified: 11/06/2019
Modified by: Christine A Hrycyna