GEOTRACES Pacific Section: Characterizing biogenic trace elements across productivity and oxygen gradients in the eastern South Pacific

将微量元素 (TE) 纳入浮游生物，以及影响这一过程的化学、地质、生物和生化机制，对于我们了解海洋的生物地球化学功能至关重要。 Fe、Zn、Co、Cu 和 Ni 等生物活性 TE 有可能控制全球海洋大片区域的海洋生产力、生态系统结构和常量营养素的利用。 已经进行了大量的实验室研究来研究模型菌株中细胞 TE 配额对不同环境条件的响应，但对细胞和从自然群落收集的生物材料中的 TE 化学计量的准确测量很少。 大颗粒颗粒 TE 化学计量的测量通常依赖于与实验室结果的比较来评估生物成分，从而排除了细胞对地球化学梯度反应的研究。在该项目中，毕格罗海洋科学实验室和缅因大学的研究人员将测量代表主要功能群的浮游生物细胞中的 TE，以及 2013 年从秘鲁到塔希提岛的美国 GEOTRACES 南太平洋带状断面沿线的大颗粒颗粒物中的 TE。国际 GEOTRACES 计划，该计划的发起是为了增进我们对海洋中 TE 的浓度、物理和化学形态以及空间分布的了解。 太平洋横断面将从具有强氧最低区的高产东部边界上升流系统延伸至东南太平洋环流，这是世界上最贫营养的区域之一。 具体来说，研究人员期望实现以下目标：（1）测量热带南太平洋东部浮游植物水平生产力梯度主要功能群中P、Si、Mn、Fe、Co、Ni、Cu和Zn的细胞配额； (2) 测量热带南太平洋东部 OMZ 垂直氧化还原梯度上浮游植物和细菌中 P、Si、Mn、Fe、Co、Ni、Cu 和 Zn 的细胞配额； (3) 使用 GO-Flo 瓶测量从上部 500 m 收集的散装颗粒材料中 Al、Ti、P、Mn、Fe、Co、Ni、Cu、Zn、Cd、V 和 Mo 的总浓度和不稳定浓度。 更广泛的影响：这项研究的更广泛影响和环境相关性将通过与 COSEE-Ocean Systems 协调组织的专门网络研讨会系列传达给教育工作者和公众。 该系列将包括 5 个按顺序举办的网络研讨会，涵盖该项目产生的科学成果，以及来自南太平洋邮轮的其他四个 GEOTRACES 项目的结果和综合。 这些研讨会将描述国际 GEOTRACES 计划的更广泛目标和意义，向教育工作者和公民推广这一全球地球化学计划，并综合该项目各个方面的研究结果（溶解的、颗粒的和生物微量金属；金属结合配体；天然放射性核素示踪剂）。 来自 GEOTRACES 的信息还将通过毕格罗的 REU 项目以及附近科尔比学院向学生教授的本科生课程介绍给本科生。

Incorporation of trace elements (TE) into plankton, and the chemical, geological, biological and biochemical mechanisms which influence this process, are of central importance to our understanding of the biogeochemical functioning of the oceans. Bioactive TEs such as Fe, Zn, Co, Cu and Ni have the potential to control ocean productivity, ecosystem structure, and the utilization of macronutrients in large regions of the global ocean. Numerous laboratory studies have been performed to study the responses of cellular TE quotas in model strains to varying environmental conditions, but accurate measurements of TE stoichiometries in cells and biogenic material collected from natural communities are rare. Measurements of bulk particulate TE stoichiometries typically rely on comparison to laboratory results to assess the biogenic component, precluding study of cellular responses to geochemical gradients.In this project, investigators at the Bigelow Laboratory for Ocean Sciences and the University of Maine will measure TEs in plankton cells representing major functional groups and in bulk particulate matter along the US GEOTRACES South Pacific Zonal Transect from Peru to Tahiti in 2013. U.S.GEOTRACES is the US component of the international GEOTRACES program which was initiated to advance our knowledge of the concentrations, physical and chemical speciation, and spatial distributions of TEs in the ocean. The Pacific transect will run from a highly productive eastern boundary upwelling system with an intense oxygen minimum zone to the southeast Pacific gyre, one of the world's most oligotrophic regimes. Specifically, the investigators expect to accomplish the following objectives: (1) Measure cellular quotas of P, Si, Mn, Fe, Co, Ni, Cu and Zn in major functional groups of phytoplankton across horizontal productivity gradients in the eastern tropical South Pacific Ocean; (2) Measure cellular quotas of P, Si, Mn, Fe, Co, Ni, Cu and Zn in phytoplankton and bacteria across vertical redox gradients in the OMZ of the eastern tropical South Pacific Ocean; ( 3) Measure total and labile concentrations of Al, Ti, P, Mn, Fe, Co, Ni, Cu, Zn, Cd, V and Mo in bulk particulate material collected from the upper 500 m with GO-Flo bottles. Broader Impacts: The broader impacts and environmental relevance of this research will be communicated to educators and the general public through a dedicated webinar series to be organized in coordination with COSEE-Ocean Systems. This series will involve 5 webinars delivered sequentially and covering the science results produced by this project, as well as results and synthesis from four other GEOTRACES projects from the South Pacific cruise. These seminars will describe the broader goals and significance of the international GEOTRACES program, promoting this global geochemical program to educators and citizens, as well as synthesizing findings on various aspects of the project (dissolved, particulate, and biogenic trace metals; metal binding ligands; natural radionuclide tracers). Information from GEOTRACES will also be introduced to undergraduate students through Bigelow's REU program and through an undergraduate course being taught to students at nearby Colby College.