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

***除了人类活动可能造成的影响外，环境中的所有微量元素（TE）都有自然来源。为了量化人为贡献，必须了解自然投入。我们使用金属已有几千年的历史。因此，为了确定大气中TE沉积的“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。沼泽是独特的生态系统，因为它们完全从空气中接受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。我们已经利用泥炭岩心重建了过去15000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，并明确区分自然和人类在当地、区域和全球尺度上对环境（空气、土壤、水、生物群）的TE贡献。***在接下来的5年里，我的研究将集中在：***1)利用藻苔作为当代大气沉积的生物监测仪；***2)利用雨养沼泽的泥炭岩心作为过去大气沉积的档案；***3)确定积雪、地表和孔隙水中TE的物理和化学形态及其对沉积后迁移的意义；***4)开发新的化学、年代地层标志，以提高年龄-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本，改进现有的自然背景“地壳气溶胶”化学成分模型。***孔隙水化学是泥炭中发生的生物地球化学转化的宝贵指南，但低浓度的TE需要极高的分析灵敏度，同时最大限度地降低样品污染的风险。确定孔隙水中分子物种的浓度更具挑战性，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超净实验室中，我们将确定天然水中的TE作为粒径的函数，测量稳定的铅同位素进行来源评估，并测量放射性（210Pb）进行年龄测定。*** HQP的新发现将为加拿大大气TE沉积提供更准确的视角，为政策制定者提供一个机会，直接比较工业创新和污染减排与环境变化的影响。HQP将发展专门知识，以便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。**************

***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. **************