Collaborative Research: 800-Year Trends in Anthropogenic and Marine Biogenic Sources of Arctic Sulfate Aerosol

近几十年来，北极经历了地球仪中最快的变暖速度。卫星观测显示，至少自1980年以来，海冰一直在减少。北极预计将在2050-2100 C.E.之间的夏季无冰。开阔的海洋和海冰都有一系列微观藻类或浮游植物群落，这些藻类群落对海冰融化的反应对海洋和大气环境都很重要，但尚不清楚。该项目旨在通过研究格陵兰冰芯中保存的含硫物质来探测、描述和理解这种反应。海洋浮游植物是大气中硫气溶胶的最大天然来源。含硫气溶胶对气候有冷却作用，因为它能有效地将阳光反射回太空。由于有效的空气污染缓解措施，化石燃料燃烧产生的硫酸盐排放量已经下降，自然来源变得更加重要。然而，目前还不清楚海冰的减少如何影响北极天然硫酸盐气溶胶的丰度。该项目将测量格陵兰冰芯记录中1200 - 2006年C.E.的硫气溶胶浮游植物来源的两个指标。这些测量将揭示海冰融化导致的硫气溶胶的浮游植物来源的任何趋势，并将为北极初级生产力和气候的未来预测提供信息。该项目的洞察力将被证明对预测浮游植物排放和气候冷却气溶胶对海冰融化的未来反应很有价值。该奖项将为华盛顿大学和南达科他州州立大学的两名研究生和几名本科生提供培训，并将支持外展活动，例如在太平洋科学中心举行的一年一度的极地科学周末上的示威活动。西雅图该奖项将支持硫酸盐的硫同位素组成和甲磺酸（MSA）浓度的测量在格陵兰冰芯中发现的海洋浮游植物向大气中排放二甲基硫（DMS）。一旦进入大气，DMS被氧化成硫气溶胶硫酸盐和MSA。硫酸盐的硫同位素来源于DMS氧化，不同于其他来源的硫酸盐，而MSA仅来源于DMS氧化。该项目将提供对过去800年来浮游植物硫气溶胶来源变化的第一个观测约束，特别关注我们知道北极海冰减少的最后35年记录。全球模型敏感性研究将通过深入了解北极硫气溶胶丰度对浮游植物排放和运输的敏感性，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进行评估，被认为值得支持的搜索.

In recent decades, the Arctic has experienced the most rapid rate of warming around the globe. Satellite observations show that sea ice has been declining since at least 1980. The Arctic is projected to be ice-free during summer starting between 2050-2100 C.E. Both the open ocean and sea ice host a range of microscopic algal or phytoplankton communities, and the response of these algal communities to melting sea ice can be important to both the marine and atmospheric environment, but is unknown. This project aims to detect, describe and understand such response by studying sulfur-containing substances preserved in a Greenland ice core. Oceanic phytoplankton are the largest natural source of sulfur aerosol to the atmosphere. Sulfur-containing aerosol has a cooling impact on climate because it efficiently reflects sunlight back to space. As the emission of sulfate from combustion of fossil fuels has declined due to effective air pollution mitigation, natural sources are becoming more important. However, it is unclear how decreasing sea ice affects the abundance of natural sulfate aerosol in the Arctic. This project will measure two indicators of the phytoplankton source of sulfur aerosol in a Greenland ice core record dating from 1200 - 2006 C.E. These measurements will reveal any trends in the phytoplankton source of sulfur aerosol resulting from melting sea ice, and will inform future predictions of Arctic primary productivity and climate. Insight from this project will prove valuable for forecasting the future response of phytoplankton emissions and climate-cooling aerosols to melting sea ice. This award will provide training for two graduate and several undergraduate students at the University of Washington and South Dakota State University, and will support outreach activities such as demonstrations at the annual Polar Science Weekend at the Pacific Science Center in Seattle, WA.This award will support measurements of the sulfur isotopic composition of sulfate and the concentration of methanesulfonic acid (MSA) in a Greenland ice core dating from 1200 - 2006 C.E. Oceanic phytoplankton emit dimethylsufide (DMS) into the atmosphere. Once in the atmosphere, DMS is oxidized to the sulfur aerosols sulfate and MSA. Sulfur isotopes of sulfate originating from DMS oxidation are distinct from other sources of sulfate, while MSA originates only from DMS oxidation. This project will provide the first observational constraint on variations in the phytoplankton source of sulfur aerosol over the past 800 years, with a particular focus on the last 35 years of the record when we know that Arctic sea ice has declined. Global model sensitivity studies will complement the ice-core record by providing insight into the sensitivity of the abundance of Arctic sulfur aerosol to phytoplankton emissions and transport, and provide quantitative insight into the climate impacts of this natural source of sulfur aerosol.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.