RUI: Do Dimethyl Sulfide (DMS) and Isoprene Control Iron Bioavailability in Marine Aerosols?

首席研究员（PI）计划一个为期两年的项目，以确定先前确定的机制的重要性，这些机制可能控制大气铁在沉积到海洋之前和之后的形态。将对先前收集的海洋气溶胶样品（南大西洋，2005年；赤道太平洋，2006年）在二甲硫醚（DMS）和异戊二烯氧化产物的存在下进行光化学实验，因为在实验室模拟中已显示这些化合物可增加铁的生物利用度。通过优化对低浓度基本化学成分的分析能力，本研究的结果将提供进一步的证据来支持或反驳浮游植物本身是反馈循环中的关键角色，以操纵气溶胶颗粒中铁的形式以实现其最佳代谢利用。沉积在海洋中的地壳气溶胶颗粒构成了稀缺微量营养素铁的重要来源，限制了偏远开阔海洋中浮游植物的生长。反过来，浮游植物通过占地球光合作用吸收二氧化碳的一半，以及通过排放气候强迫气体，如DMS和一氧化二氮（N2O），来调节全球气候。然而，公海气溶胶铁输送的系统以及控制浮游植物铁生物可利用性的化学作用仍然不明确，因此禁止对浮游植物如何影响全球气候进行任何定量分析。这项工作将由中央华盛顿大学（CWU）的本科生和硕士学生使用现有和新的仪器进行，后者将大大增加PI实验室在大气-海洋环境中研究铁的能力。参与这项研究的学生将获得宝贵的实地和实验室实践经验，并将与来自不同研究领域和国家的科学家互动，为他们应对当前和未来科学挑战的复杂性做好准备。专门为K-12学生设计的外展活动，包括全球变暖及其反馈机制的调节，将是该研究计划的组成部分。

The Principal Investigator (PI) plans a 2-year program to determine the significance of previously identified mechanisms that may control atmospheric iron speciation before and after deposition into the ocean. Photochemical experiments will be carried out on previously collected marine aerosol samples (South Atlantic Ocean, 2005; Equatorial Pacific Ocean, 2006) in the presence of dimethyl sulfide (DMS) and isoprene oxidation products, as these compounds have been shown to increase iron bioavailability in laboratory simulations. By optimizing analytical capabilities for low concentrations of essential chemical constituents, results from this study will provide further evidence to support or refute the hypothesis that phytoplankton themselves are key protagonists in a feedback cycle to manipulate the form of iron in aerosol particles for their optimal metabolic use. Crustal aerosol particles deposited at sea constitute a significant source of scarce micronutrient iron that limits phytoplankton growth in remote open oceans. Phytoplankton, in turn, modulate global climate by accounting for half the earth's photosynthetic absorption of CO2, as well as by emission of climate forcing gases, such as DMS and nitrous oxide (N2O). The systematics of open-ocean aerosol iron delivery as well as the chemistry that controls iron bioavailability to phytoplankton, however, remains ill defined thus prohibiting any quantitative analysis of how phytoplankton affect global climate. The work will be carried out by undergraduate and M.S. students at Central Washington University (CWU) with existing and new instrumentation, the latter of which will significantly increase the capacity of the PI's lab to investigate iron in the atmosphere-ocean context. Students involved in this research will obtain valuable hands-on experience in the field and the laboratory, and will interact with scientists from diverse research areas and countries, preparing them for the intricate nature of present and future scientific challenges. Outreach activities specifically designed for K-12 students that include global warming and its regulation by feedback mechanisms will be an integral part of this research program.