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

深海热液喷口是深海可溶金属的来源。在大西洋和太平洋的研究表明，这些动态系统是导致溶解铁浓度增加的原因，距离喷口所在地4000公里。先前的研究表明，从海底热液喷口释放的铁中，高达11%以黄铁矿纳米颗粒的形式存在（即，可以通过200纳米过滤器的颗粒）。这种纳米黄铁矿在海水中的氧化速率很慢，其氧化产物可以解释在深海沃茨中观察到的溶解铁的增加。这导致初级生物生产力的提高，因为铁是细菌和浮游生物所必需的微量营养素，而大型海洋生物则以它们为食。铁、钾、镁和锰也被掺入纳米级的硅酸盐和铝硅酸盐以及更大的固体矿物相，这是逆风化的一个例子。这项研究涉及实地和实验室两个组成部分，研究纳米硫化物和其他矿物的产生及其对深海铁收支的影响。实地部分涉及测量纳米级黄铁矿和其他金属硫化物相从东太平洋海隆海底热液喷口（一个快速扩展的洋中脊热液中心）散发的程度。这些样品的化学和物理分析的结果，以及实验室实验，岸上，生长和执行这些阶段的合成类似物的实验，将探索铜-硫纳米颗粒相是否是形成纳米颗粒黄铁矿和其他纳米尺寸相的晶种。它还将研究逆风化过程，即富含热金属的热液喷口沃茨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，这种情况发生在喷口口的前几米内。这项工作的更广泛影响包括博士后、研究生和本科生培训;支持一个州（特拉华州）的一个机构的研究，该机构没有获得大量的联邦资金（即，EPScoR状态）;通过海洋学研究巡航的专用网站进行公众宣传，K-12教师将参加并制作针对初中和高中学生的巡航和研究相关材料。通过特拉华州大学的海岸日，吸引了超过10,000人将进行公众宣传，以传播研究的兴奋和价值。这项研究考察了天然和合成材料。天然材料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中生成，其各种化学参数，如pH值，硫化物和金属浓度。所有颗粒将至少进行四类分析：铁和硫化物含量分析;痕量金属分析;扫描和透射电子显微镜和能量分散化学成分分析。 将用无痕量金属的钛取样器从热液喷口过滤的流体中收集天然样品。在回收天然样品后，将测量pH值，并将样品过滤在充满氩气的手套袋中。将通过电感耦合等离子体质谱法对样品进行一式三份生物活性金属（如Fe、Cu、Zn、Mn、Ni、Cd和Pb）分析。将在透射和扫描电子显微镜下检查单个颗粒，以确定其形态和矿物结构特征和尺寸。天然材料的合成类似物将在实验室中通过FeS和H2S溶液与Cu在20至150 ℃的温度下反应产生。 这些样品也将进行与天然样品相同的分析，比较结果将用于更好地了解海洋中热液喷口产生的纳米颗粒的形成和反应。

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.