Collaborative Research: Investigating tree rings as archives for atmospheric Hg concentrations using Hg, carbon isotopes, and comparisons to other proxies

合作研究：使用汞、碳同位素研究树木年轮作为大气汞浓度的档案，并与其他替代指标进行比较

• 批准号: 2152874
• 负责人: Monica Arienzo
• 金额: $ 5.78万
• 依托单位: Nevada System of Higher Education, Desert Research Institute
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2152874&HistoricalAwards=false
• 关键词: Collaborative; Research; Investigating; tree; rings

In addition to recording atmospheric conditions, trees also take up atmospheric pollutants, such as mercury, and store them in the wood they produce each year. Thus, tree rings are a promising archive of historic mercury pollution, however there remains a lot unknown about how trees take up and then store mercury in their rings. This research project aims to address this by studying how tree physiology influences how trees capture mercury from the air. Other archives of mercury (e.g. ice cores) often have high uncertainty in their dating and record mercury deposition. Comparing tree rings and other records will improve understanding of historic mercury pollution. There are very few records of mercury in the environment that are older than a few hundred years. One of the aims of this project is to develop records of up to 2000 years of atmospheric mercury, improving our understanding of natural atmospheric mercury, including how mercury is influenced by volcanic activity, wildfire and past climate changes. The knowledge and data generated in this project will be of immense value to future research projects on mercury pollution related to historic industrial practices and land-use changes, and will assist in our research into the nature and scale of industrial era mercury pollution and provide new insights to those seeking to further reduce atmospheric mercury. New reliable records of pre-industrial atmospheric mercury are also extremely important for current efforts to monitor and assess changes in mercury emissions as part of the United Nations Minamata Convention. Information, insights and approaches developed in this project will be used in exciting education and training opportunities for undergraduate and graduate students, including those from underserved groups, and in hands-on science modules for K-12 educators. Although tree-rings are a promising high-resolution archive for reconstructing past concentrations of atmospheric mercury (Hg) there remain factors that need to be further investigated. This research project aims to improve the utility of tree-rings as an Hg archive by 1) using concurrent stable carbon isotope measurements to better understand how within-tree processes related to stomatal conductance influence the incorporation of Hg into tree rings; 2) comparing concentrations of Hg in tree rings to measurements from small-catchment lake sediment and ice cores to test the fidelity of the Hg signals observed; and 3) develop long-term records of Hg concentrations derived from tree rings to investigate important natural drivers of atmospheric Hg (e.g. volcanic activity, wildfire & climate). Through the unique combination of Hg concentrations and stable carbon isotope measurements, the biotic influences on the incorporation of Hg into tree rings will be better understood. By comparing concentrations of Hg in tree rings to Hg deposition measurements from small-catchment lake sediment and ice cores, the differences and similarities between these two types of records will improve understanding of how Hg is preserved in these different archives, providing important information on post-depositional processes in depositional archives. Finally, a long-term (up to 2000 year) record of Hg concentration from tree rings will improve our understanding of natural variability in atmospheric Hg.This project is jointly funded by the Geobiology and Low-Temperature Geochemistry Program, and the Established Program to Stimulate Competitive Research (EPSCoR).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.

除了记录大气状况外，树木还吸收大气污染物，如汞，并将其储存在每年生产的木材中。因此，树木年轮是历史汞污染的一个很有前途的档案，但是关于树木如何吸收汞并将其储存在年轮中仍然有很多未知之处。该研究项目旨在通过研究树木生理学如何影响树木从空气中捕获汞来解决这一问题。其他汞档案（如冰芯）在其测年和记录汞沉积方面往往具有很高的不确定性。比较树木年轮和其他记录将提高对历史汞污染的理解。环境中汞的记录很少超过几百年。该项目的目标之一是记录长达2000年的大气汞，提高我们对自然大气汞的认识，包括汞如何受到火山活动、野火和过去气候变化的影响。本项目中产生的知识和数据将对未来与历史工业实践和土地使用变化有关的汞污染研究项目具有巨大价值，并将有助于我们研究工业时代汞污染的性质和规模，并为寻求进一步减少大气汞的人提供新的见解。工业化前大气汞的新的可靠记录对于目前作为《联合国水俣公约》一部分监测和评估汞排放变化的努力也极为重要。在这个项目中开发的信息，见解和方法将用于本科生和研究生的令人兴奋的教育和培训机会，包括来自服务不足群体的学生，以及K-12教育工作者的动手科学模块。虽然树木年轮是一个很有前途的高分辨率档案重建过去的大气汞（Hg）浓度，仍然存在的因素，需要进一步调查。该研究项目旨在通过以下方法提高树木年轮作为汞档案的效用：1）使用同步稳定碳同位素测量，更好地了解与气孔导度相关的树内过程如何影响汞进入树木年轮; 2）将树木年轮中的汞浓度与小流域湖泊沉积物和冰芯的测量结果进行比较，以测试观测到的汞信号的真实性;以及3）建立来自树木年轮的汞浓度长期记录，以调查大气汞的重要自然驱动因素（如火山活动、野火&气候）。通过汞浓度和稳定碳同位素测量的独特组合，将更好地了解生物对汞进入树木年轮的影响。通过比较树木年轮中的汞浓度与小集水湖泊沉积物和冰芯中的汞沉积测量值，这两种记录之间的差异和相似之处将有助于了解汞如何在这些不同的档案中保存，并提供关于沉积档案中沉积后过程的重要信息。最后，长期该项目由地球生物学和低温地球化学计划共同资助，激励竞争研究计划（EPSCoR）该奖项反映了NSF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。