Collaborative Research: Impacts of Recent Climate and Emissions Changes on Mercury Bioaccumulation in Arctic Marine Food-Webs

该项目旨在提高我们对控制北极汞浓度的因素及其在过去三十年(1980-2010年)的趋势的了解。它将在哈佛大学开发的全球汞化学输送模型(CTM)的基础上，开发一个北极汞的大气模型，并将进行广泛的校准和观测评估。GEOS-Chem包括大气与地表、海洋和陆地水库的动力耦合。大气中的汞(0)氧化成汞(II)，推动汞(II)的沉积，主要是通过溴(BR)原子。将利用最近来自飞机和卫星的观测来测试和改进北极BR化学的模型表示。在这项研究的所有阶段，不同的模式组件以及耦合模式将通过大量的大气观测进行详细评估。该项目将产生第一个北极大气汞动态与现有GEOS-Chem模式中海洋和陆地组件的耦合模拟。这可能是将人为排放和气候变化与北极生物汞浓度联系起来的强大工具，其强大的物理基础将使其成为检验北极汞循环和生物积累的不同假说的基本工具。使用该模型的敏感性分析将确定最不确定的领域，并有助于指导未来的研究。这项工作将使科学家和政策制定者能够更好地评估旨在保护北极环境的政策决定的影响。

This project aims to improve our understanding of the factors controlling mercury (Hg) concentrations in the Arctic and their trends over the past three decades (1980-2010). It will develop an atmospheric model for mercury in the Arctic, based on the global GEOS-Chem chemical transport model (CTM) simulation for Hg developed at Harvard, and will be calibrated extensively and evaluated with observations. GEOS-Chem includes dynamical coupling of the atmosphere with surface ocean and land reservoirs. Atmospheric oxidation of Hg(0) to Hg(II), driving Hg(II) deposition, is primarily by bromine (Br) atoms. Model representation of Br chemistry in the Arctic will be tested and improved using recent observations from aircraft and satellites. At all stages of this research, the different model components as well as the coupled model will be evaluated in detail with a large body of atmospheric observations.The project will produce the first coupled simulation of atmospheric Hg dynamics in the Arctic with the ocean and land components in the existing GEOS-Chem model. This can be a powerful tool for relating changes in anthropogenic emissions and climate to biological Hg concentrations in the Arctic and its strong physical basis will make it a fundamental vehicle to test different hypotheses for Hg cycling and bioaccumulation in the Arctic. Sensitivity analyses using the model will identify areas of greatest uncertainty and help guide future research. This work will enable scientists and policymakers to better assess the impacts of policy decisions aimed at protecting the arctic environment.