Collaborative Research: Source apportionment of iron in the marine atmosphere - application of stable iron isotopic measurements

合作研究：海洋大气中铁的来源解析——稳定铁同位素测量的应用

• 批准号: 1031371
• 负责人: Ariel Anbar
• 金额: $ 22.52万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-10-01 至 2014-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1031371&HistoricalAwards=false
• 关键词: Collaborative; Research; Source; apportionment; iron

In many regions of the world's ocean, primary productivity is not limited by the major nutrients (nitrogen, phosphorous and silica) but by the micronutrient iron (Fe). One major source of Fe is the atmospheric transport and deposition of aerosols to the open ocean. The aerosols come from natural sources, such as soils and dust and biomass burning, and from anthropogenic emissions related to industrial processes and energy generation. Our understanding of the sources is limited by our ability to identify the origin of the Fe. Mechanisms of tracing the sources of aerosols include the use of the elemental ratios as specific sources have specific elemental signals. Fe isotopic variation has recently been demonstrated to be a potentially important tracer of Fe sources. This project, a collaboration between investigators at Arizona State University and Northern Arizona University, will explore the use of Fe isotopes as a tracer of natural and anthropogenic sources of aerosols to assess their importance as a source of Fe to the open ocean. Fe is known to limit primary production in many high nutrient, low chlorophyll areas, so it is important to understand the origin of the Fe that is delivered to the oceans and its availability to marine microorganisms. Additionally, aerosols from different sources have variable size and solubility in seawater and therefore this also impacts Fe bioavailability. Examination of the isotopes of Fe in aerosols could help address these questions as the investigators' prior research has demonstrated distinct variations in the isotopic composition of aerosol Fe that arise from natural and anthropogenic sources. The study will measure the Fe isotopic compositions of aerosol particles collected on Bermuda over a period of one year. Bermuda was chosen as seasonal differences lead to different aerosol types being deposited - summer winds flow from the east and carry Saharan soil dust and other aerosols, while winter winds originate from over North America. The project will compare the Bermuda results with that of key anthropogenic and natural aerosol materials that could be a source of Fe to the Atlantic Ocean. In addition, elemental analyses of these aerosols will provide an independent confirmation of the Fe isotopes results. Analysis of size-segregated samples will provide additional information and will be coupled with solubility experiments designed to assess the soluble Fe fraction. Broader Impacts: The scientific impact of this work relates to obtaining a better understanding of the factors that impact the sources and availability of Fe, an important limiting micronutrient, to the ocean, and to marine microorganisms. As a part of the proposed project, the investigators will develop interactive educational activities to teach the major concepts of ocean nutrient availability and limitation to non-science students, which will be part of a new course "Habitable Worlds". Additionally, the proposed project will support graduate student training, and benefit under-represented groups.

在世界海洋的许多区域，初级生产力不受主要营养素（氮、磷和二氧化硅）的限制，而是受到微量营养素铁（Fe）的限制。铁的主要来源之一是大气中气溶胶的输送和沉积到公海。气溶胶来自自然资源，例如土壤、灰尘和生物质燃烧，以及与工业过程和能源生产相关的人为排放。我们对来源的了解受到我们识别铁来源的能力的限制。追踪气溶胶来源的机制包括使用元素比率，因为特定来源具有特定的元素信号。 Fe 同位素变化最近被证明是 Fe 来源的潜在重要示踪剂。该项目由亚利桑那州立大学和北亚利桑那大学的研究人员合作，将探索使用铁同位素作为自然和人为气溶胶来源的示踪剂，以评估其作为公海铁来源的重要性。众所周知，铁会限制许多高营养、低叶绿素地区的初级生产，因此了解输送到海洋的铁的来源及其对海洋微生物的可用性非常重要。此外，不同来源的气溶胶在海水中的大小和溶解度各不相同，因此这也会影响铁的生物利用度。对气溶胶中铁同位素的检查可能有助于解决这些问题，因为研究人员之前的研究已经证明，自然和人为来源的气溶胶铁同位素组成存在明显差异。该研究将测量一年内在百慕大收集的气溶胶颗粒的铁同位素组成。选择百慕大是因为季节性差异导致不同的气溶胶类型沉积 - 夏季风从东部吹来，携带撒哈拉土壤灰尘和其他气溶胶，而冬季风则来自北美上空。该项目将把百慕大的结果与可能成为大西洋铁来源的关键人为和天然气溶胶材料的结果进行比较。此外，这些气溶胶的元素分析将为铁同位素结果提供独立的确认。对尺寸分离样品的分析将提供额外的信息，并将与旨在评估可溶性铁分数的溶解度实验相结合。更广泛的影响：这项工作的科学影响涉及更好地了解影响海洋和海洋微生物铁（一种重要的限制性微量营养素）的来源和可用性的因素。作为拟议项目的一部分，研究人员将开发互动教育活动，向非理科学生教授海洋营养物可用性和限制的主要概念，这将是新课程“宜居世界”的一部分。此外，拟议的项目将支持研究生培训，并使代表性不足的群体受益。