RII Track-4: NSF: Source fingerprinting of mercury isotopes in thermokarst lake systems

存在于北半球大部分地区的永久冻土是汞的巨大储存库。目前尚不清楚永久冻土产生的汞在多大程度上可被生物体和食物网吸收。因此，本研究将为阿拉斯加费尔班克斯大学（UAF）的一名非终身研究助理教授提供为期两年的奖学金，通过访问、培训和在美国地质调查局汞研究实验室（USGS MRL）的合作，提高其研究能力。这项研究将通过测量环境样本中汞的自然丰度同位素比率，研究沿永久冻土梯度的湖泊系统中汞的命运。美国地质调查局MRL的研究小组是国际公认的，并拥有一个最先进的科学实验室，配备了高精度和精密测量汞同位素比率的专用仪器。首席研究员将参加长期访问，以学习适当的采样技术，并与美国地质勘探局的科学家合作，分析从北部湖泊系统收集的环境样本。在合作访问期间获得的技能将有利于UAF和阿拉斯加州解决与气候变化相关的复杂问题。此外，这项研究将填补与永久冻土释放的汞的命运有关的知识空白。这个研究基础设施改善轨道4 EPSCoR研究人员（RII轨道4）项目将为阿拉斯加费尔班克斯大学的研究助理教授提供奖学金。这项工作将与位于威斯康星州麦迪逊市的美国地质调查局汞研究实验室（USGS MRL）的研究人员合作进行。最近的估计表明，永久冻土是汞的重要储存库，而由于气候变化，汞很容易被释放。热岩溶湖能迅速降解永久冻土，因此，热岩溶湖在从永久冻土中调动汞方面可能特别重要。汞在这些系统中的环境命运仍然是一个重大的知识缺口。自然丰度汞同位素比值的测量是当前汞研究的前沿，是识别汞源的有力工具，可以为汞的生物地球化学循环提供额外的理解。迄今为止，大多数汞同位素研究都是在低纬度系统中进行的。因此，描述永久冻土汞同位素末端成员的信息有限，这将对研究人员在试图确定这一潜在的重要汞来源对北极食物网的命运时大有裨益。首席研究员将对美国地质调查局的MRL进行长期访问，在那里他将使用最先进的科学仪器，并学习与汞同位素分析相关的适当的环境采样、分析和解释技能。在美国地质勘探局MRL期间，首席研究员还将与美国地质勘探局的专家合作，分析从跨越纬度和融化梯度的热岩溶湖收集的空气、水、沉积物、永久冻土土壤和新兴昆虫样本中汞的自然丰度同位素比率。通过这些分析，研究小组将确定永久冻土汞进入当代热岩溶湖食物网的程度。这项研究的结果将广泛传播。首席研究员将访问阿拉斯加土著社区，讨论环境汞研究，并将在会议报告和同行评议的出版物中传播项目结果。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Permafrost soils, which are present across a large portion of the Northern Hemisphere, are a vast reservoir for mercury. It remains unclear to what extent permafrost-derived mercury is available for uptake into organisms and food webs. Accordingly, this research will provide funding for a two-year fellowship to increase the research capacity of a non-tenure track Research Assistant Professor at the University of Alaska Fairbanks (UAF) through visits, training, and collaboration at the United States Geological Survey Mercury Research Laboratory (USGS MRL). This research will investigate the fate of mercury in lake systems along a permafrost gradient through the measurement of natural abundance isotope ratios of mercury in environmental samples. The USGS MRL’s research group is internationally recognized and maintains a state-of-the-science laboratory equipped with dedicated instrumentation for high accuracy and precision measurements of mercury isotope ratios. The lead researcher will participate in extended visits to learn appropriate sampling techniques and collaborate with USGS scientists to analyze environmental samples collected from the northern lake systems. The skills gained during the collaborative visits will benefit UAF and the State of Alaska as they tackle the complex problems associated with climate change. Additionally, the research will fill knowledge gaps related to the fate of mercury released from permafrost.This Research Infrastructure Improvement Track-4 EPSCoR Research Fellows (RII Track-4) project would provide a fellowship to a Research Assistant Professor at the University of Alaska Fairbanks. This work would be conducted in collaboration with researchers at the United States Geological Survey Mercury Research Laboratory (USGS MRL) in Madison, Wisconsin. Recent estimates indicate that permafrost soils are a significant reservoir of mercury, which is vulnerable to release due to climate change. Thermokarst lakes degrade permafrost rapidly and thus, thermokarst lakes may be particularly important in mobilizing mercury from permafrost stores. The environmental fate of mercury in these systems remains a major knowledge gap. The measurement of natural abundance mercury isotope ratios, which is at the forefront of current mercury research, is a powerful tool for mercury source identification and can provide additional understanding of mercury biogeochemical cycling. To date, most mercury isotope studies have been carried out in lower latitude systems. Thus, there is limited information characterizing the isotopic endmember of permafrost mercury, which would be of great benefit to researchers as they attempt to determine the fate of this potentially important source of mercury to Arctic food webs. The lead researcher will make extended visits to the USGS MRL, where he will make use of state-of-the science instrumentation and learn the appropriate environmental sampling, analytical, and interpretation skills related to mercury isotope analyses. While at the USGS MRL, the lead researcher will also work collaboratively with USGS experts to analyze natural abundance isotope ratios of mercury in samples of air, water, sediment, permafrost soil, and emergent insects collected from thermokarst lakes spanning a latitudinal and thaw gradient. By means of these analyses, the research team will identify to what extent permafrost mercury is entering contemporary thermokarst lake food webs. Results of this research will be communicated broadly. The lead researcher will make visits to an Alaska Native community to discuss environmental mercury research and will disseminate project results in conference presentations and peer-reviewed publications.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.