Collaborative Research on Snow and Ice Processes in the Deposition and Fate of Mercury in the Arctic

北极汞沉积和归宿中冰雪过程的合作研究

• 批准号: 0435893
• 负责人: Joel Blum
• 金额: --
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-01 至 2007-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0435893&HistoricalAwards=false
• 关键词: Collaborative; Research; Snow; Ice; Processes

Atmospheric mercury enters the arctic ecosystem through a set of complex atmospheric chemical reactions that require sea ice and leads to provide reactive bromine, low ambient temperatures, and enough sunlight for photolysis. As a consequence, virtually all atmospheric mercury entering the arctic ecosystem is initially deposited in the snow pack, both on land and at sea. Up to one third of this initial deposit is re-emitted to the atmosphere before the snow melts, but the remainder ends up in snow melt run-off. The fate of this water-borne mercury is uncertain and undoubtedly different on land vs. sea ice. Two key unanswered questions are: How much of the elemental mercury initially deposited is converted to toxic methyl-mercury, and where does this methylmercury ultimately come to rest? Since cryospheric processes related to snow and ice in large measure determine the answers to these questions, this work sets out to study these processes. The processes studied straddle the Arctic Coast, have pan-Arctic significance, and have a direct impact on human and ecosystem health. The project has experimental and synthesis components. Along a transect from the Chukchi Sea inland to Barrow and Atqasuk, measurements will be taken of reactive bromine and mercury loading in the snow pack. Detailed observations will be made during mercury depletion events and during the snowmelt, comparing and contrasting the fate of mercury on land with that at sea. Post snowmelt samples from tundra, lakes, ice, and terrestrial and marine sediments will be analyzed and used to determine where and how much of the deposited mercury is converted to methyl mercury. Manipulation experiments will be used to better understand how mercury is entrained in the snow pack, and how it is released during the snowmelt. A series of weeklong retreats by the research team and selected others will be held to produce a synthesis of the Arctic Mercury System. By understanding and modeling the arctic mercury system, the group will assess how the impact of mercury pollution on human and biological systems is likely to be affected by the unprecedented changes in sea ice and snow conditions that are taking place in the Arctic today. Intellectual Merit of Proposed Activity: The research fills a gap in our current understanding of the Arctic Mercury System, namely what happens to atmospheric mercury after it is deposited. It also serves as a bridge, connecting detailed studies of atmospheric chemistry of mercury deposition with the large body of studies related to arctic mercury environmental loading and health risk. This work takes a systems approach to the mercury problem that is both essential and novel. Broader Impacts: Mercury is toxic and of great concern to arctic residents and officials. Results from this research will be useful in assessing how arctic mercury pollution is derived from global levels of mercury, and how that pollutant loading might respond to changes in sea ice and snow conditions. Results will be communicated to decision-makers and the public in a series of outreach activities that include traditional graduate student training, conference presentations, website publication, classroom visits, and through the production and publication of a children's book by an award-winning author.

大气中的汞通过一系列复杂的大气化学反应进入北极生态系统，这些化学反应需要海冰和铅来提供活性溴、较低的环境温度和足够的阳光以进行光解。因此，几乎所有进入北极生态系统的大气汞最初都沉积在陆地和海洋的积雪中。在雪融化之前，高达三分之一的初始沉积物会重新排放到大气中，但其余部分最终会形成融雪径流。这种水载汞的命运是不确定的，而且在陆地冰和海冰上无疑是不同的。两个尚未解答的关键问题是：最初沉积的元素汞中有多少转化为有毒的甲基汞，以及这些甲基汞最终停留在哪里？由于与冰雪相关的冰冻圈过程在很大程度上决定了这些问题的答案，因此这项工作着手研究这些过程。研究的过程横跨北极海岸，具有泛北极意义，并对人类和生态系统健康产生直接影响。 该项目有实验和合成部分。沿着从楚科奇海内陆到巴罗和阿特卡苏克的横断面，将测量积雪中的活性溴和汞含量。将在汞消耗事件和融雪期间进行详细观察，比较和对比汞在陆地上和海洋中的命运。来自苔原、湖泊、冰以及陆地和海洋沉积物的融雪后样本将被分析并用于确定沉积的汞在何处以及有多少转化为甲基汞。操纵实验将用于更好地了解汞是如何夹带在积雪中以及在融雪过程中如何释放的。研究小组和选定的其他人将举行一系列为期一周的静修活动，以综合研究北极水星系统。通过了解和模拟北极汞系统，该小组将评估当今北极海冰和雪条件发生的前所未有的变化可能如何影响汞污染对人类和生物系统的影响。 拟议活动的智力价值：这项研究填补了我们目前对北极汞系统理解的空白，即大气汞沉积后会发生什么。它还充当一座桥梁，将汞沉积大气化学的详细研究与有关北极汞环境负荷和健康风险的大量研究联系起来。这项工作采用系统方法来解决汞问题，既重要又新颖。 更广泛的影响：汞有毒，引起北极居民和官员的高度关注。这项研究的结果将有助于评估北极汞污染如何源自全球汞水平，以及污染物负荷如何响应海冰和雪条件的变化。研究结果将通过一系列外展活动传达给决策者和公众，包括传统的研究生培训、会议演讲、网站出版、课堂参观以及获奖作者制作和出版儿童读物。