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

在浮游生物中加入微量元素，以及影响这一过程的化学、地质、生物和生化机制，对于我们理解海洋的生物地球化学功能是至关重要的。铁、锌、钴、铜和镍等生物活性物质有可能在全球海洋的大片区域控制海洋生产力、生态系统结构和大量营养素的利用。已经进行了大量的实验室研究，以研究模式菌株中细胞TE配额对不同环境条件的响应，但从自然群落收集的细胞和生物材料中的TE化学计量的准确测量很少。散装颗粒物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因成分，排除了细胞对地球化学梯度的响应。在这个项目中，毕格罗海洋科学实验室和缅因州大学的研究人员将于2013年测量代表主要功能群的浮游生物细胞和美国GEOTRACES南太平洋带状样带从秘鲁到塔希提岛的散装颗粒物中的TES。美国GEOTRACES是国际GEOTRACES计划的美国组成部分，该计划的发起是为了促进我们对海洋中TES的浓度、物理和化学形态以及空间分布的了解。太平洋横断面将从生产力高的东部边界上升流系统和高氧最低限度区域延伸到东南太平洋环流，这是世界上营养最少的地区之一。具体地说，研究人员期望完成以下目标：(1)测量热带南太平洋东部水平生产力梯度上浮游植物主要功能群中P、Si、Mn、Fe、Co、Ni、Cu和Zn的细胞配额；(2)测量东热带南太平洋OMZ浮游植物和细菌中P、Si、Mn、Fe、Co、Ni、Cu和Zn的细胞配额；(3)用Go-Flo瓶测定500米以上颗粒物中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：这项研究的更广泛的影响和与环境的相关性将通过与COSEE-Ocean Systems协调组织的一系列专门的网络研讨会向教育工作者和公众宣传。这一系列活动将包括先后举办的5个网络研讨会，涵盖该项目产生的科学成果，以及南太平洋邮轮的另外四个地球物理轨道系统项目的成果和综合。这些研讨会将描述国际GEOTRACES计划更广泛的目标和意义，向教育工作者和公民宣传这一全球地球化学计划，并综合该项目各个方面的研究成果(溶解的、微粒的和生物来源的痕量金属；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教授的本科课程向本科生介绍。

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.