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

微量元素（TE）与浮游生物的结合以及影响这一过程的化学、地质、生物和生物化学机制对我们理解海洋的地球化学功能至关重要。 具有生物活性的铁、锌、钴、铜和镍等微量元素有可能控制海洋生产力、生态系统结构和全球海洋大面积区域的常量营养素利用。 人们已经进行了许多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，但对从自然群落收集的细胞和生物源材料中TE化学计量的准确测量却很少见。 大量颗粒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，排除了对地球化学梯度的细胞响应的研究。毕格罗海洋科学实验室和缅因州大学的研究人员将测量代表主要功能群的浮游生物细胞和沿着美国地理跟踪南太平洋带状断面从秘鲁到2013年的大溪地。 美国GEOTRACES是国际GEOTRACES计划的美国组成部分，该计划旨在促进我们对海洋中TE浓度，物理和化学形态以及空间分布的了解。 太平洋样带将从一个高产的东部边界上升流系统与一个强烈的氧气最低区的东南太平洋环流，世界上最贫营养的制度之一。 具体而言，研究人员预计将实现以下目标：（1）测量热带南太平洋东部浮游植物主要功能群中跨水平生产力梯度的P、Si、Mn、Fe、Co、Ni、Cu和Zn的细胞配额;（2）测定磷、硅、锰、铁、钴、镍、热带南太平洋东部大洋有机带浮游植物和细菌中Cu和Zn的垂直氧化还原梯度（3）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：这项研究的广泛影响和环境相关性将通过与COSEE海洋系统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。 这一系列将包括5个网络研讨会，按顺序提供，涵盖该项目产生的科学成果，以及南太平洋巡航中其他四个GEOTRACES项目的成果和综合。 这些研讨会将描述国际GEOTRACES计划的更广泛的目标和意义，向教育工作者和公民推广这一全球地球化学计划，并综合该项目各方面的研究结果（溶解，颗粒和生物痕量金属;金属结合配体;天然放射性核素示踪剂）。 来自GEOTRACES的信息也将通过毕格罗的REU项目和附近科尔比学院的本科课程介绍给本科生。

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.