Trace Element Organic Speciation along the US GEOTRACES Pacific Meridional Transect

美国 GEOTRACES 太平洋经向断面沿线的微量元素有机形态

基本信息

批准号：
1736280
负责人：
Daniel Repeta
金额：
$ 63.98万
依托单位：
Woods Hole Oceanographic Institution
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-01-01 至 2021-12-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1736280&HistoricalAwards=false
关键词：
Trace Element Organic Speciation along

项目摘要

In many areas of the ocean microbes live in an environment that has very little of the nutrients they need to grow and thrive. In particular, nutrients with nitrogen (N), phosphorus (P), and iron (Fe), needed for the synthesis of proteins and nucleic acids, are in short supply. Iron is supplied to the ocean by dust blowing off the continents, and in areas remote from land, microbial life is limited by the very low concentrations of iron dissolved in seawater. To extract iron from their surroundings, some microbes synthesize and release organic compounds called siderophores into their environment. Siderophores are specifically designed to bind iron and transport it back into the cell. But only recently have we had the technology to measure siderophores in seawater, and we do not know where or when they are used, or which microbes are making and using them. The study proposed here is designed to address all of these questions. We will measure siderophores in the Pacific Ocean along a track from Alaska to Tahiti. The distribution of siderophores will be compared with data from other measurements (nutrients, cell numbers, genomics) to understand how microbes are able to live in very low iron environments, and how they can use organic compounds to extract metals from seawater. The study will also allow us test and improve the technology of measuring iron and other metals (mercury, copper, and cadmium, for example) bonded to organic compounds in other environmental samples, such as ground-waters, lakes and rivers, which is important for monitoring the toxicity of metal contaminants. Nearly all iron dissolved in the ocean is complexed by strong organic ligands of unknown composition. The effect of ligand composition on microbial iron acquisition is poorly understood, but amendment experiments using model ligands show they can facilitate or impede iron uptake depending on their identity. Here we propose to measure the molecular speciation of a suite of bioactive trace element (iron, copper, cobalt, nickel, and zinc) ligands (TE-Ls) in particulate and dissolved organic matter across the US GEOTRACES Pacific Meridional Transect (PMT). We will use high pressure liquid chromatography coupled to inductively coupled plasma mass spectrometry to detect and quantify TE-Ls, and companion electrospray ionization mass spectra to identify and characterize organic ligands. The PMT will cross five different biogeochemical provinces: shelf/slope, subarctic high nutrient/low chlorophyll (HNLC), North Pacific oligotrophic gyre, equatorial HNLC, and South Pacific oligotrophic gyre. The cruise track further intersects at least three different subsurface features, the subarctic and equatorial particle veils, oxygen deficient waters, and mid depth hydrothermal plumes. We expect the unique physical, chemical, and biological properties that characterize these regimes and features will lead to very different TE-L distributions across and down the water column. TE-L molecular speciation measurements will enable us to better integrate datasets of trace element distribution with metagenomic datasets of nutrient-driven changes in microbial metabolism across some of the Earth?s major biomes.

在海洋的许多地区，微生物生活的环境中其生长和繁衍所需的营养物质非常少。特别是蛋白质和核酸合成所需的氮（N）、磷（P）和铁（Fe）等营养物质供应短缺。铁是通过从大陆吹走的尘埃供给海洋的，而在远离陆地的地区，微生物的生命受到海水中溶解铁浓度极低的限制。为了从周围环境中提取铁，一些微生物会合成称为铁载体的有机化合物并将其释放到环境中。铁载体专门设计用于结合铁并将其运回细胞内。但直到最近，我们才拥有了测量海水中铁载体的技术，但我们不知道它们在何处或何时使用，也不知道哪些微生物正在制造和使用它们。这里提出的研究旨在解决所有这些问题。我们将沿着从阿拉斯加到塔希提岛的轨道测量太平洋中的铁载体。铁载体的分布将与其他测量数据（营养物、细胞数量、基因组学）进行比较，以了解微生物如何能够在铁含量极低的环境中生存，以及它们如何利用有机化合物从海水中提取金属。这项研究还将使我们能够测试和改进测量与其他环境样本（例如地下水、湖泊和河流）中的有机化合物结合的铁和其他金属（例如汞、铜和镉）的技术，这非常重要用于监测金属污染物的毒性。几乎所有溶解在海洋中的铁都是由未知成分的强有机配体络合的。配体组成对微生物铁获取的影响知之甚少，但使用模型配体的修正实验表明，它们可以根据其特性促进或阻碍铁的吸收。在这里，我们建议测量美国 GEOTRACES 太平洋经线横断面 (PMT) 颗粒物和溶解有机物中一套生物活性微量元素（铁、铜、钴、镍和锌）配体 (TE-L) 的分子形态。我们将使用高压液相色谱与电感耦合等离子体质谱联用来检测和定量 TE-L，并使用配套的电喷雾电离质谱来识别和表征有机配体。 PMT将穿越五个不同的生物地球化学省：陆架/斜坡、亚北极高营养/低叶绿素（HNLC）、北太平洋寡营养环流、赤道HNLC和南太平洋寡营养环流。巡航轨迹还与至少三个不同的地下特征相交，即亚北极和赤道粒子遮蔽、缺氧水域和中深度热液羽流。我们预计表征这些状态和特征的独特物理、化学和生物特性将导致水体上和下游的 TE-L 分布非常不同。 TE-L 分子形态测量将使我们能够更好地将微量元素分布数据集与地球一些主要生物群系中营养驱动的微生物代谢变化的宏基因组数据集整合起来。