Collaborative Research: Soil-Snow-Atmosphere Exchanges of Mercury in the Interior Arctic Tundra

合作研究：北极苔原内陆的土壤-雪-大气交换

• 批准号: 1304202
• 负责人: Detlev Helmig
• 金额: $ 41.69万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-10-01 至 2018-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1304202&HistoricalAwards=false
• 关键词: Collaborative; Research; Soil; Snow; Atmosphere

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. Proposed 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 proposed 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.

该项目的目的是表征雪地为主的北极苔原中汞（HG）的土壤 - 鼻子 - 大气动力学。积雪中汞的化学转化从非挥发性形式转化为气态元素汞（GEM）可以导致雪地的大量脱气，从而减少大气沉积的影响。与在中纬度的积雪中看到的宝石化学反应相反，在阿拉斯加布鲁克斯山脉北坡的Toolik Lake的初步观察提供了证据，表明光化学的宝石形成和脱气被抑制在苔原雪中，并且在整个冬季，冬季的大部分时间实际上都转化为非载质HG。这些模式会导致长时间的插入性积雪空气在宝石中耗尽。如果得到证实，这种化学可能意味着大气宝石向雪或潜在的土壤的净转移，从而增加了进入苔原生态系统的HG沉积。拟议的项目目标是研究（1）确定北极积雪和苔原土壤中GEM耗竭和形成的频率和基础过程； （2）宝石动力学在土壤，雪和大气之间导致垂直HG交换的程度； （3）这些过程如何提供其他来源＆＃8722;或水槽＆＃8722;通过大气表面转移和融雪的输入。在Toolik Field Station中将对土壤，雪和空气以及垂直交换的宝石浓度以及垂直交换。测量将通过降雪歧管系统进行，以便在不受干扰的雪堆和大气中多个深度的痕量气体进行全自动和连续的全冬测量。这些实验将通过通量室测量补充，以评估潜在的苔原土壤的贡献。将纳入其他痕量气体观测以及土壤，雪，融化水和土壤水的化学表征，以评估有关GEM动力学和HG预算的环境和生物地球化学控制。这项拟议的研究将利用工具野外站的持续lter和霓虹灯项目，从而在雪地内的过程，苔原土壤和淡水生物地球化学循环，北极进口污染和生态系统过程之间提供联系。该项目将直接涉及高中，本科生，研究生和博士后科学家。它将通过研究结果在课堂，实验室旅行和数据分析中的研究演讲扩大与当地高中化学课程的现有伙伴关系。将通过同行评审的出版物和会议演讲以及与美国和国际监管机构的沟通来实现对科学界的传播。将通过新闻发布，机构出版物，开放日活动和网站来联系公众。数据将在科罗拉多大学的国家冰雪数据中心存档，以分发到国家和国际极地研究界。