Peat Bogs: Environmental Archives of Atmospheric Trace Elements (PEAATE)

泥炭沼泽：大气微量元素的环境档案 (PEAATE)

• 批准号: RGPIN-2018-04892
• 负责人: Shotyk, William
• 金额: $ 8.89万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=764531
• 关键词: Peat; Bogs; Environmental; Archives; Atmospheric

All trace elements (TE) in the environment have a natural source, in addition to possible contributions from human activities. To quantify anthropogenic contributions, natural inputs must be known. We have used metals for thousands of years. Thus, to identify “background” rates of atmospheric deposition of TE, we need to go back in time, and this requires the judicious use of environmental archives such as peat bogs. Bogs are unique ecosystems because they receive inputs of TE exclusively from the air. While bogs are excellent environmental archives of atmospheric deposition, we have a limited understanding of how they function. We have used peat cores to reconstruct atmospheric lead deposition for the past 15,000 years, but still cannot explain why lead and other TE are so well preserved in the acidic, organic-rich, anoxic peat.The long-term objective of my program is to understand how peat bogs function as archives of atmospheric TE deposition, and to clearly distinguish between natural and human contributions of TE to the environment (air, soil, water, biota) at local, regional, and global scales.Over the next 5 years my research will focus on:1) the use of Sphagnum moss as biomonitors of contemporary atmospheric deposition;2) using peat cores from rain-fed bogs as archives of atmospheric deposition in the past; 3) determining the physical and chemical forms of TE in snow, surface and pore waters, and their significance for post-depositional migration;4) developing new chemical, chronostratigraphic markers for improving the reliability of our age-depth models; and 5) improving the existing model for the chemical composition of the natural, background “crustal aerosol” using our collection of ancient peat samples from five continents.Porewater chemistry is a valuable guide to the biogeochemical transformations taking place within the peat, but the low concentrations of TE require tremendous analytical sensitivity while minimizing the risk of sample contamination. Determining the concentrations of molecular species in porewaters is even more challenging, but key to understanding the ecological significance (bioaccessibility and bioavailability) of TE emissions to the environment. In our state-of-the-art, metal-free, ultraclean lab we will determine TE in natural waters as a function of particle size, measure stable lead isotopes for source assessment, and radioactive (210Pb) for age dating. The new discoveries to be made by HQP will present a more accurate perspective on atmospheric deposition of TE in Canada, providing policy-makers with an opportunity to directly compare the effects of industrial innovation and pollution abatement with environmental change. The HQP will develop the expertise to better understand the true impacts of resource development and other human activities around the world, ultimately leading to a cleaner and safer environment.

环境中的所有微量元素（TE）除了可能来自人类活动外，还有天然来源。为了量化人为贡献，必须知道自然投入。我们使用金属已经有几千年了。因此，要确定大气沉积TE的“背景”速率，我们需要回到过去，这需要明智地使用环境档案，如泥炭沼泽。沼泽地是独特的生态系统，因为它们只从空气中接收TE的输入。虽然沼泽是大气沉积的优秀环境档案，但我们对它们如何发挥作用的了解有限。我们已经使用泥炭芯重建了过去15,000年的大气铅沉积，但仍然无法解释为什么铅和其他TE在酸性、富含有机物、缺氧的泥炭中保存得如此完好。我的项目的长期目标是了解泥炭沼泽如何作为大气TE沉积的档案，并明确区分TE对环境的自然和人类贡献在未来5年里，我的研究将集中在：1）泥炭藓作为现代大气沉积的生物监测器;2）来自雨养沼泽的泥炭芯作为过去大气沉积的档案; 3）确定TE在雪、表面和孔隙沃茨中的物理和化学形式，以及它们对沉积后迁移的意义; 4）开发新的化学、年代地层标志物，以提高我们的年龄-深度模型的可靠性; 5）利用我们从五大洲收集的古代泥炭样品，改进现有的天然背景“地壳气溶胶”化学成分模型。孔隙水化学是泥炭内部发生的地球化学变化的有价值的指南，但是低浓度的TE需要极大的分析灵敏度，同时使样品污染的风险最小化。确定孔隙水中分子种类的浓度更具挑战性，但这是了解TE排放对环境的生态意义（生物可及性和生物利用度）的关键。在我们最先进的、无金属的超净实验室中，我们将确定天然沃茨中的TE随粒径的变化，测量稳定的铅同位素用于来源评估，并测量放射性（210 Pb）用于年龄测定。HQP的新发现将为加拿大大气中TE的沉积提供更准确的视角，为政策制定者提供直接比较工业创新和污染减排与环境变化的影响的机会。HQP将发展专业知识，以更好地了解世界各地资源开发和其他人类活动的真正影响，最终实现更清洁、更安全的环境。