Accomplishment Based Renewal (ABR): Pyrite, metal sulfide and aluminosilicate nanoparticles as kinetically stable sources of iron and other metals to the ocean

基于成就的更新（ABR）：黄铁矿、金属硫化物和铝硅酸盐纳米颗粒作为海洋中铁和其他金属的动力学稳定来源

• 批准号: 1558712
• 负责人: George Luther
• 金额: $ 45.97万
• 依托单位: University of Delaware
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-15 至 2021-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1558712&HistoricalAwards=false
• 关键词: Accomplishment; Based; Renewal; ABR; Pyrite

Deep-sea hydrothermal vents are sources of soluble metals to the deep ocean. Research in the Atlantic and Pacific Oceans has shown that these dynamic systems are responsible for increases in dissolved iron concentrations up to 4000 kilometers away from where the vents are located. Previous work has shown that up to 11% of the iron released from seafloor hydrothermal vents exists as pyrite nanoparticles (i.e., particles that can pass thorough a 200 nanometer filter). This nano-pyrite, which has a slow oxidation rate in seawater, and its oxidation products can account for the observed increase in dissolved iron in deep ocean waters. This results in enhanced primary biological productivity because iron is an essential micronutrient for bacteria and plankton upon which larger marine organisms feed. Iron, potassium, magnesium and manganese also get incorporated into nano-sized silicates and aluminosilicates as well as larger solid mineral phases, an example of reverse weathering. This research involves both field and laboratory components that examine the production and impact of nano-sulfides and other minerals on the deep ocean iron budget. The field component involves measuring the extent to which nanoparticle-sized pyrite and other metal sulfide phases emanate from seafloor hydrothermal vents on the East Pacific Rise, a fast spreading mid-ocean ridge hydrothermal center. Results of the chemical and physical analysis of these samples, as well as laboratory experiments, onshore, that grow and perform experiments with synthetic analogs of these phases will explore whether copper-sulfur nanoparticulate phases are seed crystals for the formation of nanoparticulate pyrite and other nano-sized phases. It will also examine the process of reverse weathering, which is how silicate and aluminosilicate nanoparticles form and react when hot metal-rich hydrothermal vent waters interact with cold seawater on the ocean floor, something that occurs within the first couple of meters of the vent orifice. Broader impacts of the work include postdoctoral and graduate and undergraduate student training; support of research at an institution in a state (Delaware) that does not receive significant amounts of federal funding (i.e., an EPScoR state); and public outreach via a dedicated website for the oceanographic research cruise on which a K-12 teacher will attend and produce cruise and research related materials targeted to middle and high school students. Public outreach via the University of Delaware's Coast Day which attracts over 10,000 people will be carried out to transmit the excitement and value of the research. This research examines both natural and synthetic materials. Natural materials will come from hydrothermal vents located at 9-10 degrees north latitude in the central Pacific Ocean; and synthetic analog materials, for which various chemical parameters such as pH, sulfide, and metal concentrations, will be generated onshore in the laboratory. All particles will undergo, at a minimum, four types of analyses: analysis of the Fe and sulfide content; analysis of trace metals; and scanning and transmission electron microscopic and energy dispersive chemical compositional analysis. Natural samples will be collected from fluids filtered from hydrothermal vents with trace-metal-clean titanium samplers. Upon retrieval of the natural samples, pH will be measured and samples will be filtered in an argon filled glove bag. Samples will be analyzed in triplicate via inductively coupled plasma mass spectrometry for bioactive metals like Fe, Cu, Zn, Mn, Ni, Cd, and Pb. Individual particles will be examined under the transmission and scanning electron microscopes to determine their morphology and mineral structural characteristics and sizes. Synthetic analogs to the natural materials will be generated in the lab by reacting solutions of FeS and H2S with Cu at temperatures from 20 to 150 C. These will also undergo the same analyses as the natural samples with results of the comparison being used to better understand the formation and reactivity of hydrothermal vent originated nanoparticles in the ocean.

深海热液喷口是深海中可溶金属的来源。在大西洋和太平洋的研究表明，这些动力系统导致离喷口最远4000公里处的溶解铁浓度增加。以前的工作表明，从海底热液喷口释放的铁中，高达11%以黄铁矿纳米颗粒(即可以通过200纳米过滤器的颗粒)的形式存在。这种在海水中氧化速度较慢的纳米黄铁矿及其氧化产物可以解释观察到的深海水域中溶解铁的增加。这提高了初级生物生产力，因为铁是大型海洋生物赖以生存的细菌和浮游生物所必需的微量营养素。铁、钾、镁和锰也会被结合到纳米硅酸盐和铝硅酸盐以及更大的固体矿物相中，这是反向风化的一个例子。这项研究涉及实地和实验室两个部分，考察纳米硫化物和其他矿物的生产及其对深海铁收支的影响。现场部分包括测量从东太平洋隆起海底热液喷口发出的纳米颗粒尺寸的黄铁矿和其他金属硫化物相的程度，东太平洋隆起是一个快速扩张的大洋中脊热液中心。这些样品的化学和物理分析结果，以及在陆地上生长并使用这些相的合成类似物进行实验的实验室实验，将探索铜硫纳米相是否是形成纳米黄铁矿和其他纳米相的种子晶体。它还将研究反向风化过程，这是富含金属的热水喷口与海底冷海水相互作用时，硅酸盐和铝硅酸盐纳米颗粒是如何形成和反应的，这种情况发生在通风口前几米内。这项工作的更广泛影响包括博士后、研究生和本科生培训；支持在没有获得大量联邦资金的州(特拉华州)的机构进行研究(例如，EPSCoR州)；通过海洋研究巡游的专用网站进行公共宣传，K-12教师将参加并制作针对初中生的巡游和研究相关材料。将通过特拉华大学的海岸日进行公众宣传，吸引了超过1万人，以传播这项研究的兴奋和价值。这项研究考察了天然材料和合成材料。天然物质将来自位于中太平洋北纬9-10度的热液喷口；合成模拟材料将在实验室陆上产生各种化学参数，如pH、硫化物和金属浓度。所有颗粒将至少接受四种类型的分析：铁和硫化物含量的分析；痕量金属的分析；以及扫描和透射电子显微镜和能量分散化学成分分析。自然样品将从热液喷口用微量金属清洁的钛采样器过滤的流体中采集。在取回天然样品后，将测量PH值，并将样品放入充气手套袋中过滤。样品将通过电感耦合等离子体质谱进行一式三份的生物活性金属分析，如铁、铜、锌、锰、镍、镉和铅。单个颗粒将在透射和扫描电子显微镜下进行检查，以确定它们的形态以及矿物结构特征和大小。实验室将通过FeS和H2S的溶液与铜在20至150℃的温度下反应生成天然材料的合成类似物。这些溶液也将接受与自然样品相同的分析，比较结果将用于更好地了解海洋中热液喷口来源的纳米颗粒的形成和反应性。