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性金属的来源。在大西洋和太平洋的研究表明，这些动态系统是导致离火山口4000公里远的地方溶解铁浓度增加的原因。先前的研究表明，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氧化速度慢，其氧化产物可以解释深海中溶解铁的增加。这导致初级生物生产力的提高，因为铁是大型海洋生物赖以为生的细菌和浮游生物必需的微量营养素。铁、钾、镁和锰也被纳入纳米级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。这项研究包括实地和实验室组成部分，检查纳米硫化物和其他矿物对深海铁预算的生产和影响。现场部分包括测量纳米颗粒大小的黄铁矿和其他金属硫化物相从东太平洋隆起海底热液喷口散发的程度，东太平洋隆起是一个快速扩张的洋中脊热液中心。这些样品的化学和物理分析结果，以及岸上的实验室实验，用这些相的合成类似物生长和进行实验，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种子晶体。它还将研究反向风化过程，即当富含金属的热液喷口水与海底的冷海水相互作用时，硅酸盐和铝硅酸盐纳米颗粒是如何形成和反应的，这种反应发生在喷口的前几米内。更广泛的影响包括博士后、研究生和本科生的培养；支持在没有获得大量联邦资金（即EPScoR州）的州（特拉华州）的机构进行研究；通过海洋学研究游轮的专门网站进行公众宣传，一名K-12教师将参加该网站，并制作针对初高中学生的游轮和研究相关材料。通过特拉华大学海岸日的公众宣传活动，将吸引超过10,000人，以传递研究的兴奋和价值。这项研究考察了天然材料和合成材料。天然物质将来自太平洋中部北纬9-10度的热液喷口；合成模拟材料，其各种化学参数，如pH值、硫化物和金属浓度，将在实验室陆上产生。所有颗粒至少要经过四种分析：铁和硫化物含量的分析；微量金属分析；以及扫描透射电镜和能量色散化学成分分析。天然样品将从热液喷口过滤的液体中收集，使用痕量金属清洁的钛采样器。在提取自然样品后，pH值将被测量，样品将在充满氩气的手套袋中过滤。样品将通过电感耦合等离子体质谱分析三份生物活性金属，如Fe， Cu, Zn, Mn, Ni， Cd和Pb。单个颗粒将在透射和扫描电子显微镜下进行检查，以确定其形态和矿物结构特征和尺寸。与天然材料类似的合成物将在实验室中通过FeS和H2S溶液与Cu在20至150℃的温度下反应生成，这些材料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性。

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.