Collaborative Research: Atmospheric Processing of Iron--Does Particle Size Influence Iron Solubility?

该项目将研究粒径对铁的大气反应的影响，进而研究粒径对铁溶解度的影响。 特别是，颗粒大小如何影响铁的溶解度在大气处理过程中的两种不同的机制将进行调查。 首先，将确定在云沃茨中铁的光还原过程中粒径对铁溶解度的影响。 在真实的和模拟的云沃茨中，含水铁的光化学还原已经被很好地研究，然而，颗粒尺寸从未被认为是一个变量，但可能是重要的，因为只有有限的气溶胶尺寸分数可以形成云凝结核（CCN）。 以前的实验室研究集中在颗粒太大或太小，作为云凝结核可能低估或高估的可溶性铁产生的光化学在真实的大气系统。 其次，将研究颗粒尺寸对与气态二氧化硫反应期间铁溶解度的影响。将在两种相对湿度（20%和80%）下分别研究与氯化钠混合的铁相的暴露，这两种相对湿度分别代表干燥的大陆和潮湿的海洋环境。 这将允许确定在铁-硫相互作用期间气体-颗粒反应还是液体-颗粒反应更重要。 在暴露于二氧化硫之后，溶解的铁部分的铁同位素组成将被确定并用于阐明机制。这项研究将对了解大陆和海洋气溶胶中铁的溶解度做出有价值的贡献。 这些结果将与大气铁如何影响海洋生产力以及其与全球碳循环的关系这一更广泛的问题有关。 铁是一种限制营养素在许多地区的开放的海洋和大量的努力已经提出，以确定铁的可用性大气颗粒物的海洋生物。 这项研究还将促进下一代大气科学家的培训。 该项目将资助一名博士。亚利桑那州州立大学的一名学生，这项研究是他/她论文工作的核心。 此外，每年将有一名来自北方亚利桑那大学（NAU）的本科生与主要研究者和博士合作。ASU的学生。 化学系在NAU是一个非博士。授予部门。 因此，与ASU研究人员的合作将为NAU的本科生提供在NAU通常不可能的研究方法和技术方面的培训。 此外，NAU是授予美国原住民学生学位的国家领导人之一。 这些独特的人口统计数据将通过NAU的部落环境专业人员研究所招募以环境为重点的美国原住民本科生。

This project will examine the influence of particle size on atmospheric reactions of iron and, in turn, the influence of particle size on iron solubility. In particular, how particle size affects iron solubility during atmospheric processing by two different mechanisms will be investigated. First, the effect of particle size on iron solubility during photoreduction of iron in cloud waters will be determined. Photochemical reduction of aqueous iron has been well studied in authentic and simulated cloud waters, however, particle size has never been considered as a variable but may be important because only a restricted aerosol size fraction can form cloud condensation nuclei (CCN). Previous laboratory studies focusing on particles too big or too small to act as CCN may under- or overestimate the soluble iron resulting from photochemistry in real atmospheric systems. Second, the influence of particle size on iron solubility during reaction with gaseous sulfur dioxide will be investigated. Exposure of iron phases mixed with sodium chloride will be studied at two relative humidities (20% and 80%) representative of dry continental and wet marine environments, respectively. This will allow determination of whether gas-particle or liquid-particle reactions are more important during iron-sulfur interactions. Following exposure to sulfur dioxide, the iron isotope composition of the dissolved iron fraction will be determined and used to elucidate mechanisms.This research will be a valuable contribution to understanding iron solubility in continental and marine aerosols. The results will be relevant to the broader question of how atmospheric iron affects ocean productivity and, hence, its relation to the global carbon cycle. Iron is a limiting nutrient in many parts of the open ocean and substantial effort has been put forth to determine the availability of iron in atmospheric particulate matter to marine life. This study will also advance the training of the next generation of atmospheric scientists. The project will fund one Ph.D. student at Arizona State University (ASU), with this research being the core of his/her thesis work. In addition, one undergraduate student each year from Northern Arizona University (NAU) will work with the principal investigators and the Ph.D. student at ASU. The Department of Chemistry at NAU is a non-Ph.D. granting department. Therefore, collaboration with ASU researchers will provide undergraduate students at NAU training in research approaches and techniques that are not normally possible at NAU. Furthermore, NAU is among the national leaders in granting degrees to Native American students. These unique demographics will be drawn upon to recruit environmentally-focused Native American undergraduates through the Institute for Tribal Environmental Professionals at NAU.