Science Summary: The goal of this project is to characterize soil-snow-atmosphere dynamics of mercury (Hg) in the snow-dominated Arctic tundra. Chemical conversion of Hg in snowpack from non-volatile forms to gaseous elemental mercury (GEM) can lead to substantial degassing of Hg from snow, thereby reducing the impact of atmospheric deposition. Contrary to the GEM chemistry seen in the midlatitude snowpack, preliminary observations from Toolik Lake, on the north slope of the Brooks Range, Alaska, provide evidence that photochemical GEM formation and degassing are suppressed in tundra snow and that for much of the winter, interstitial GEM is actually converted into non-volatile Hg. These patterns result in extended periods when interstitial snowpack air is depleted in GEM. If confirmed, this chemistry would likely signify a net transfer of atmospheric GEM to snow or underlying soils, thereby increasing Hg deposition to tundra ecosystems. Project objectives are to investigate (1) the frequency and underlying processes that determine GEM depletion and formation in arctic snowpack and tundra soils; (2) the degree to which GEM dynamics cause vertical Hg exchange between soils, snow, and the atmosphere; and (3) how these processes provide additional sources - or sinks - of Hg via atmosphere-surface transfer and snowmelt input. GEM concentrations in soils, snow, and air, as well as vertical exchanges, will be characterized at Toolik Field Station. Measurements will be made by means of a snow-sampling manifold system allowing for fully automated and continuous all-winter measurements of trace gases at multiple depths in the undisturbed snowpack and the atmosphere. These experiments will be supplemented by flux chamber measurements to assess the contribution of the underlying tundra soils. Other trace gas observations, and chemical characterization of soil, snow, melt water, and soil water will be incorporated to assess the environmental and biogeochemical controls on GEM dynamics and the Hg budget. This research will leverage ongoing LTER and NEON projects at the Toolik Field station, providing linkages between in-snow processes, tundra soil and freshwater biogeochemical cycling, pollution import into the Arctic, and ecosystem processes. The project will directly involve high school, undergraduate, graduate students, and a postdoctoral scientist. It will expand an existing partnership with local high school chemistry classes through research presentations in classrooms, laboratory tours, and data analyses using study results. Dissemination to the scientific community will be accomplished through peer-reviewed publications and conference presentations, and by communication with U.S. and international regulatory agencies. The general public will be reached through news releases, institutional publications, open house events, and a web site. Data will be archived at the National Snow and Ice Data Center at the University of Colorado for distribution to the national and international polar research community.
Logistics Summary: Researchers on this collaborative project between Obrist (1739567, UMass) and Helmig (1304202, CU) will conduct measurements of soils-snow-atmosphere dynamics of mercury and other trace gases at Toolik Field Station in Alaska. The goal of this project is to quantify atmospheric deposition, re-emission, and mobilization of mercury in snowpack and soils of this Arctic tundra for the duration of one full year.
In August 2014 a team of five researchers will travel to Toolik Field Station for the set up and installation of project instrumentation. For each subsequent month, a single researcher will travel to Toolik for data collection and instrument maintenance, with two researchers making the trip in September 2016 for instrument demobilization.
Under NSF Supplement #1458858 the field work was extended from May 2016 to the first week of September 2016.
Instrumentation at Toolik Field Station will continue to operate and collect data through fall 2017. Other work to be continued under this grant for the remainder of 2017 includes ongoing laboratory analysis for Hg, trace metals, organic carbon and nitrogen are ongoing and samples are being processed by graduate and undergraduate students. As well as continued data analysis and QA/QC procedures have been performed and are ongoing to develop a final dataset of two full years of field measurements.
*Note: In 2017 the PI transferred from Nevada System of Higher Education, Desert Research Institute to University of Massachusetts Lowell, details for previous work is carried under NSF grant 1304305.
IAB will provide access to services and infrastructure at Toolik Field Station. CPS will provide user days at TFS for the duration of this project. CPS will remove the infrastructure when field work is complete. All other logistics, including any land use permits, will be arranged and paid for by the PI from the research grant.
Alaska - Toolik
Parameters used to generate this report:, Grant# = "1739567", IPY = "ALL"
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