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U.S. GEOTRACES PMT: Measurement of the organic complexation and chemical lability of dissolved copper using multiple techniques

美国 GEOTRACES PMT：使用多种技术测量溶解铜的有机络合和化学不稳定性

基本信息

批准号：
1756415
负责人：
James Moffett
金额：
$ 26.33万
依托单位：
University of Southern California
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-03-01 至 2022-05-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1756415&HistoricalAwards=false
关键词：
U.S.GEOTRACES PMT Measurement organic

项目摘要

Copper (Cu) is an element in the ocean that is essential for life. Like many elements taken up by marine life, its concentrations in seawater are very low; however, Cu has a distribution in the water column that is different from other biologically essential elements. This difference may be attributed to the presence of a residual fraction in seawater that is virtually inert. This project seeks to understand what this material is, why it is so unreactive, and how it can eventually be 'cracked" and re-enter the biological cycle. A scientist from the University of Southern California (USC) will characterize the Cu chemistry during the US GEOTRACES Pacific Meridional Transect (PMT) cruise. This cruise is a north-south transect from Alaska to Tahiti that spans a wide range of water depths, temperatures, biology, and chemistry. The Cu measurements will be made alongside many other trace elements that have different chemistries. By comparing their behavior, coupled with the knowledge of each element?s chemical properties, the scientist will further our knowledge of what controls the behavior of Cu in the ocean. Training of graduate students and outstanding undergraduates in the speciation techniques is planned. The graduate students will also mentor high school students from inner city schools through the USC Young Investigators Program. The cruise and its findings will be incorporated into outreach activities and courses taught at USC, including a general education class for non-science majors.A scientist from USC hypothesizes that non-labile complexes will predominate in high-scavenging regimes and that labile forms will accumulate in older deep waters above a non-labile background pool. To quantify the distribution and chemical properties, two different speciation techniques will be used based on competitive ligand exchange. The first, adsorptive cathodic stripping voltammetry, was used on previous GEOTRACES sections. The second is based on a ligand exchange, liquid/liquid partition methodology developed by the researcher. Partitioning leads to physical separation of fractions that are reactive or not with the competitive ligand allowing the exchangeability of strongly complexed copper by using Cu-65 as a tracer. The tracer enables much slower reactions to be studied experimentally. Samples will be analyzed using isotope dilution by inductively coupled plasma-mass spectrometry. Samples will also be prepared for natural Cu isotope analysis of non-labile Cu by a colleague at USC (Seth John) to test the hypothesis that non-labile or semi-labile complexes contribute to the heavy isotope signature of dissolved Cu in seawater. The PMT enables high volume sample collection from deep waters at the terminus of the oceanic conveyor belt, along with data for particulate metals and isotope tracers of scavenging. Moreover, the relationship between labile and non-labile Cu can be studied over several distinct biomes, including high-nutrient, low chlorophyll regions and oligotrophic subtropical gyres along the PMT.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

铜（Cu）是海洋中生命所必需的元素。像海洋生物吸收的许多元素一样，它在海水中的浓度非常低；然而，铜在水柱中的分布与其他生物必需元素不同。这种差异可能是由于海水中存在一种实际上是惰性的残余部分。该项目旨在了解这种材料是什么，为什么它如此不活跃，以及它最终如何被“破解”并重新进入生物循环。来自南加州大学（USC）的一名科学家将在美国GEOTRACES太平洋经向样带（PMT）巡航期间描述铜的化学性质。这是一条从阿拉斯加到塔希提岛的南北横断面，跨越了广泛的水深，温度，生物和化学。铜的测量将与许多其他具有不同化学性质的微量元素一起进行。通过比较他们的行为，再加上每个元素的知识？科学家将进一步了解是什么控制了铜在海洋中的行为。计划培养研究生和优秀本科生的物种形成技术。研究生还将通过南加州大学青年调查员计划指导来自市中心学校的高中生。这次航行及其发现将被纳入南加州大学的外展活动和课程中，包括一门针对非科学专业学生的通识教育课程。南加州大学的一位科学家假设，非稳定的复合物将在高清除机制中占主导地位，而不稳定的形式将积聚在非稳定背景池上方的较老的深水中。为了量化分布和化学性质，将使用基于竞争配体交换的两种不同的物种形成技术。第一种是吸附阴极溶出伏安法，用于之前的GEOTRACES剖面。第二种是基于配体交换，液体/液体分配方法开发的研究人员。分配导致与竞争配体反应或不反应的分数的物理分离，允许使用Cu-65作为示踪剂的强络合铜的互换性。示踪剂使实验研究更慢的反应成为可能。样品将通过电感耦合等离子体质谱法进行同位素稀释分析。南加州大学的一位同事（Seth John）也将准备样品，用于对非不稳定Cu进行天然Cu同位素分析，以验证非不稳定或半不稳定配合物有助于海水中溶解Cu的重同位素特征的假设。PMT能够从海洋传送带末端的深水中收集大量样本，以及颗粒金属和同位素示踪剂的清除数据。此外，在PMT沿线的高营养、低叶绿素区和副热带少营养环流等不同的生物群系中，可以研究稳定和非稳定Cu之间的关系。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。