Collaborative Research: Impacts of Global Change on Terrestrial Mercury in the Arctic

北半球的永久冻土层含有大量与冰冻有机物结合的汞。北极的变暖速度是全球平均速度的两到三倍。随着永久冻土的融化，有机物的微生物腐烂将恢复，将汞释放到环境中。科学界缺乏了解永久冻土融化对北极和全球汞循环的影响所需的基于过程的陆地汞模型。该项目将利用现有的陆地碳循环模型来建立这样的模型，以促进我们在多个时空尺度上对永久冻土区陆地汞过程的理解。该项目将使用这些模型来预测永久冻土融化释放的汞对泛北极和全球的影响。这个项目将首次揭示北极系统中两个相互关联的组成部分的紧急行为：碳循环和汞循环。该项目将利用和加强现有的模型来评估永久冻土融化产生的汞将如何影响北极和全球汞循环。该项目有两个目标：1)量化不同环境条件对汞积累的影响以及相关的不确定性；2)量化冻土融化释放的汞如何影响全球汞循环及其相关的不确定性。本项目采用三种陆地汞循环模型：1)全物理简单生物圈卡内基-艾姆斯-斯坦福方法（SiBCASA）模型；2)与三维大气输送和海洋环流模式耦合的全球陆地汞模型（GTMM）；3)简单的全球生物地球化学盒模型（GBBM）。利用SiBCASA对公元1400年至2300年的模拟将提供从永久冻土融化中释放的未来汞的估计。GTMM模拟将量化永久冻土融化释放的汞对全球的影响。蒙特卡罗模拟与GBBM将量化不确定性。这些模型需要基于汞吸收和释放途径的最新知识进行改进。这些增强包括新的生物地球化学池，如土壤水，新的过程，如火，和新的计算技术，如蒙特卡罗模拟。该项目的更广泛影响包括对早期职业研究人员的指导，组织培训研讨会以架起汞和碳研究界的桥梁，以及生产公开可用的产品，其中包括更新的汞排放数据集，模型本身，模型的输出，以及将模型结果可视化的在线工具。该项目利用陆地碳途径的广泛知识来参数化汞途径，并将陆地汞和碳循环耦合起来。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。

Northern hemisphere permafrost contains a large amount of mercury (Hg) bound to frozen organic matter. The Arctic is warming at two to three times the global average rate. As permafrost thaws, microbial decay of the organic matter will resume, releasing mercury into the environment. The scientific community lacks the process-based terrestrial mercury models needed to understand the impacts of permafrost thaw on the Arctic and global mercury cycles. This project will build such models by leveraging existing models of the terrestrial carbon cycle to advance our understanding of terrestrial mercury processes in permafrost regions at multiple temporal and spatial scales. The project will use these models to predict the pan-Arctic and global impacts of Hg released from thawing permafrost. For the first time, this project will reveal the emergent behavior of two linked components of the Arctic system: the carbon and mercury cycles.This project will leverage and enhance existing models to evaluate how Hg from thawing permafrost will influence the Arctic and global Hg cycles. The project has two objectives: 1) Quantify how different environmental conditions affect Hg accumulation with associated uncertainties; and 2) Quantify how Hg released from thawing permafrost impacts the global Hg cycle with associated uncertainties. This project uses three models of the terrestrial Hg cycle: 1) the full-physics Simple Biosphere Carnegie-Ames-Stanford Approach (SiBCASA) model; 2) the Global Terrestrial Mercury Model (GTMM) coupled to 3-D atmospheric transport and ocean circulation models; and 3) a simple Global Biogeochemical Box Model (GBBM). Simulations from 1400 to 2300 CE using SiBCASA will provide estimates of future Hg releases from thawing permafrost. Simulations with GTMM will quantify global impacts of Hg released from thawing permafrost. Monte Carlo simulations with GBBM will quantify uncertainty. These models require enhancement based on the latest knowledge of Hg uptake and release pathways. These enhancements include new biogeochemical pools such as soil water, new processes such as fire, and new computational techniques such as Monte Carlo simulations. The Broader Impacts of this project include the mentoring of early-career researchers, the organization of a training workshop to bridge the Hg and carbon research communities, and the production of publicly available products, which include an updated Hg emissions dataset, the models themselves, output from the models, and an on-line tool to visualize the model results. This project leverages extensive knowledge of terrestrial carbon pathways to parameterize Hg pathways and couple the terrestrial Hg and carbon cycles.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.