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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）是海洋中对生命至关重要的元素。与海洋生物吸收的许多元素一样，铜在海水中的浓度很低;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几乎惰性的残余部分。该项目旨在了解这种材料是什么，为什么它如此不反应，以及它如何最终被“破解”并重新进入生物循环。来自南加州大学（USC）的一位科学家将在美国GEOTRACES太平洋经向断面（PMT）巡航期间描述铜的化学性质。这次巡航是从阿拉斯加到塔希提岛的南北样带，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。通过比较它们的行为，再加上对每个元素的了解？科学家将进一步了解是什么控制了铜在海洋中的行为。计划对研究生和优秀本科生进行物种形成技术培训。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，包括为非科学专业开设的通识教育课程。南加州大学的一位科学家假设，在高清除率的环境中，不稳定的复合物将占主导地位，而不稳定的形式将在不稳定背景池上方的较老的深水沃茨中积累。为了量化分布和化学性质，将基于竞争性配体交换使用两种不同的形态分析技术。第一，吸附阴极溶出伏安法，用于以前的GEOTRACES部分。第二种是基于研究人员开发的配体交换，液/液分配方法。分配导致物理分离的馏分是反应性的或不与竞争性配体允许交换的强烈络合的铜通过使用Cu-65作为示踪剂。示踪剂使慢得多的反应能够进行实验研究。将通过电感耦合等离子体质谱法使用同位素稀释法分析样品。南加州大学的一位同事（Seth John）还将准备样品，用于对非不稳定铜进行天然铜同位素分析，以检验非不稳定或半不稳定络合物对海水中溶解铜的重同位素特征有贡献的假设。PMT能够从海洋传送带末端的深沃茨收集大量样品，沿着颗粒金属和同位素示踪剂的数据。此外，不稳定和非不稳定铜之间的关系可以在几个不同的生物群落，包括高营养，低叶绿素地区和贫营养亚热带环流沿着PMT进行研究。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。