Mercury Contamination and Biogeochemical Cycling in the Arctic

关于极地地区汞在大气、陆地和海洋中的循环或污染源汞的影响，人们的知识有限。大气是汞在地球表面转移的主要途径。迁移的主要物质是元素汞（Hg 0），在大气中的停留时间为1 - 2年。因此，自然和人为的汞可以很容易地在半球内和半球间扩散，包括北极。首席研究员将提出四个假设：1）美国偏远的北极地区受到汞污染增加的影响，与其他偏远地区观察到的情况相似; 23个贫营养北极湖泊具有显著的汞流失，特别是Hg 0，如果这些湖泊表现得像温带湖泊系统，那么，高pH值、较高的反应水平汞含量和更多的还原剂就地供应将有利于Hg 0的就地产生和排放;第三章在北极地区观测到了来自其他地区的北极雨水中汞和210 Pb之间的线性相关性，这种行为可以用来限制大气的潮湿汞向湖泊和流域的通量; 4）Hg 0是北极湖泊氧化带中主要的汞循环产物，在氧化还原带过渡带中，一甲基汞（MMHg）的净原位合成最为显著。这些活动分为四类：1）大气汞沉积和形态测定; 2）沉积物芯收集，汞分析和使用210 Pb测年的地质年代学; 3）湖泊汞形态和循环研究;和4）实验室模拟和孵化实验。这项研究将为定量评估过去150年来与人类有关的汞排放提供所需的高质量生物化学数据。它应有助于解读这种沉积影响的当前和历史证据，这些证据反映在MMHg在水生生态系统中的产生和积累，以及由于污染源汞的存在而导致的水源汞自然再排放的放大。这些信息将改进全球和区域汞的生物化学循环模型，并评估源自污染物的汞对环境的影响。

AbstractOPP-9908895FitzgeraldLimited knowledge exists on atmospheric, terrestrial and marine cycling of mercury in the polar regions or on the impact from pollution-derived mercury The atmosphere is the principle route by which mercury is transferred at the Earth's surface. The major species transported is elemental mercury (Hg0) which has an atmospheric residence time of one-two years. Therefore, natural and anthropogenic mercury can be readily dispersed intra- and inter-hemispherically, including the Arctic.The Principal Investigator will address four hypotheses: 1) the remote U.S. Arctic region has been affected by increases in mercury contamination similar to that observed in other remote regions; 23 oligotrophic Arctic lakes have significant evasional losses of mercury, especially Hg0 if these lakes behave like temperate lacustrine systems, then in-situ Hg0 production and emission will be favored by high pH, higher reactive levels mercury levels and a greater in-situ supply of reducing agents; 3) the linear correlation between mercury and 210Pb found in Arctic rainwater from other locations is observed in the Arctic and this behavior can be used to constrain wet atmospheric flux of mercury to lakes and watersheds; 4) Hg0 is the predominant mercury cycling product in the oxic zone of the Arctic lakes, net in-situ synthesis of monomethylmercury (MMHg) is most significant in redox zones transition zones.The Principal Investigator will develop an experimental design which includes extensive field and laboratory investigations. These activities are divided into four categories: 1) atmospheric mercury deposition and speciation deterininations; 2) sediment core collection, mercury analysis and geochronology using 210Pb dating; 3) in-lake mercury speciation and cycling studies; and 4) laboratory simulations and incubation experiments. This research should provide high quality biogeochemcial data needed for quantitative assessment of the human-related mercury emissions over the past 150 years. It should help to decipher current and historic evidence of the impact from this deposition as reflected by MMHg production and accumulation in aquatic ecosystems and amplification in the natural re-emission of mercury from water sources due to the presence of pollutant-derived mercury. This information will improve models of the global.and regional biogeochernical cycling of mercury and assessing the impact associated with pollutant-derived mercury in the environment.