US GEOTRACES PMT: Cobalt Biogeochemical Cycling and Connections to Metalloenzymes in the Pacific Ocean

钴对多种海洋生物都很重要，但它是海洋中最稀缺的营养物质之一。钴在海洋中的丰度和分布以及其他稀缺营养物质可以影响微观植物（浮游植物）的生长。这反过来又会影响海洋和大气中的碳循环。因此，了解海水中钴的丰度和化学形态的控制知识是我们了解海洋对全球碳循环影响的能力的重要组成部分。在浮游植物和其他海洋微生物中，钴、铁、镍和铜等金属被用作负责关键细胞反应的酶的关键成分。由于这些酶需要金属才能发挥作用，因此被称为金属酶。该项目将参加从阿拉斯加到塔希提岛的太平洋航行，研究溶解钴的海洋分布以及一组已知影响生物地球化学循环的金属酶的细胞含量。该项目将通过在渔业和深海采矿方面具有经济利益的地区创造有关海洋微量营养素的新知识来产生科学影响。北太平洋蛋白质的测量将提供具有广泛生物和化学意义的数据，并将通过国家科学基金会资助的新“EarthCube海洋蛋白质门户”数据库提供。教育影响将源于一名研究生和两名年轻技术人员的参与，以及 PI 开发的高中化学课程供当地两所高中使用，从而使教师能够在第一次介绍化学时包含真实的海洋和环境数​​据。钴具有复杂的生物地球化学循环。 它的无机和有机形式都被上层海洋的生物所利用，并通过在中层和深海中被清除而从溶液中去除。这种清除去除导致钴在所有生物利用元素中具有最小的海洋库存量。然而，最近的研究发现，由于沉积和再矿化通量较少的清除和添加，在主要的最低氧区域出现了大量溶解的钴羽流。 GP15 US GEOTRACES 太平洋经线横断面 (PMT) 提供了一个研究缺氧对钴化学影响的机会。此外，使用新的蛋白质组学技术对微生物群落的蛋白质成分进行研究将提供不同主要微生物如何响应化学环境的证据（例如通过特定营养素和微量营养素的转运蛋白生产）以及与特定金属酶的使用相关的金属需求的生化基础。具体来说，PMT提供了一个机会来确认太平洋最低含氧区含有大量钴，并检验同时缺锌可能导致北太平洋钴对锌的大规模生化替代的假设。

Cobalt is important for many forms of marine life, yet it is one of the scarcest nutrients in the sea. Cobalt's oceanic abundance and distribution, along with other scarce nutrients, can influence the growth of microscopic plants (phytoplankton). This in turn can influence carbon cycles in the ocean and atmosphere. Therefore, knowledge of the controls on cobalt's abundance and chemical forms in seawater is a valuable component of our ability to understand the ocean's influence on global carbon cycling. Within phytoplankton and other marine microbes, metals such as cobalt, iron, nickel, and copper are used as critical components of enzymes responsible for key cellular reactions. Since these enzymes require metals to work, they are named metalloenzymes. Participating in a Pacific Ocean cruise from Alaska to Tahiti, this project will study the oceanic distributions of dissolved cobalt and the cellular content of a group of metalloenzymes known to influence biogeochemical cycles. The project will provide scientific impact by creating new knowledge about oceanic micronutrients in regions of economic interest with regard to fisheries and deep-sea mining. Measurement of proteins in the North Pacific will provide data of broad biological and chemical interest and will be made available through a new NSF-funded "EarthCube Ocean Protein Portal" data base. Educational impact will stem from participation of a graduate student and two young technicians, as well as the PI's development of a high school chemistry curriculum for use in two local high schools, thus allowing teachers to include real oceanic and environmental data at their first introduction to chemistry.Cobalt has a complex biogeochemical cycle. Both its inorganic and organic forms are used by biology in the upper ocean and it is removed from solution by being scavenged in the intermediate and deep ocean. This scavenging removal results in cobalt having the smallest oceanic inventory of any biologically utilized element. Recent studies, however, have found that large dissolved cobalt plumes occur in major oxygen minimum zones due to a combination of less scavenging and additions from sedimentary and remineralization fluxes. The GP15 US GEOTRACES Pacific Meridional Transect (PMT) provides an opportunity to examine the influence of oxygen depletion on cobalt chemistry. Moreover, the study of the protein component of microbial communities using new proteomic techniques will provide evidence of how different major microorganisms respond to the chemical environment (e.g. through transporter production for specific nutrients and micronutrients) as well as the biochemical basis for metal requirements related to the use of specific metalloenzymes. Specifically, the PMT provides an opportunity to confirm that the Pacific oxygen minimum zones contain a large amount of cobalt and to test the hypotheses that simultaneous zinc scarcity could induce wide-scale biochemical substitution of cobalt for zinc in the North Pacific Ocean.