Collaborative Research: Seawater Inorganic and Organic Carbon Measurements for the US GEOTRACES Eastern Pacific Zonal Transect

来自百慕大海洋科学研究所和加州大学圣巴巴拉分校的科学家们计划在2013年GEOTRACES东太平洋带状样带巡航期间收集样本，并分析其溶解无机碳、溶解有机碳（DOC）和总碱度。所得数据将非常精确，可用于计算pH值和海水碳酸盐化学（例如，氢氧化物，碳酸盐离子，碳酸钙矿物的饱和状态）。考虑到pH对氧化还原化学、物种形成和配体-颗粒-微量金属/同位素相互作用的影响，从秘鲁到塔希提岛的样带及其海洋海水碳酸盐化学范围将为验证以下假设提供机会：(1)pH是控制微量元素及其同位素（TEIs）分布及其在水柱内动力学的关键约束条件；(2) DOC与TEIs相互作用，提供一系列影响微量元素溶解度、络合和形态形成的结合配体。此外，由于巡航路线将经过东太平洋隆起，科学家们计划评估热液羽流中DOC的变化，并确定DOC和颗粒有机碳之间有机物的分配。在与其他GEOTRACES研究人员的合作下，这些数据将用于评估铁、铜、钴和汞的形态，并借助迈阿密大学罗森斯蒂尔海洋与大气科学学院的一名合作者获得的氯氟化碳数据，确定海洋表层DOC的去除率。就更广泛的影响而言，该项目将产生高质量的数据集，不仅有利于GEOTRACES社区，帮助他们解释其痕量金属和同位素测量结果，也有利于其他参与有机/无机碳循环研究的科学家。加州大学圣巴巴拉分校的一名研究生将作为该项目的一部分得到支持和培训。

Scientists from Bermuda Institute of Ocean Sciences and the University of California, Santa Barbara, plan to collect samples during the 2013 GEOTRACES Eastern Pacific Zonal Transect cruise and analyze them for dissolved inorganic carbon, dissolved organic carbon (DOC), and total alkalinity. The resultant data will be highly precise and accurate to allow calculation of pH and seawater carbonate chemistry (e.g., hydroxide, carbonate ion, saturation sate for calcium carbonate minerals). Given the influence of pH on redox chemistry, speciation, and ligand-particle-trace metal/isotope interactions, the transect from Peru to Tahiti with its range of marine seawater carbonate chemistry will provide an opportunity to test the hypotheses that (1) pH is a critical constraint for controlling distributions of trace elements and their isotopes (TEIs) and their dynamics within the water column, and; (2) DOC interacts with TEIs providing a spectrum of binding ligands that influence trace element solubility, complexation, and speciation. Also, because the cruise track will pass over the East Pacific Rise, the scientists plan to evaluate DOC variability within the hydrothermal plume and determine the partitioning of organic matter between DOC and particulate organic carbon. In collaboration with other GEOTRACES researchers, the data will be used to assess the speciation of iron, copper, cobalt and mercury, as well as determine the removal rate of DOC from the surface ocean with the help of chlorofluorocarbon data obtained by a collaborator from the University of Miami, Rosenstiel School of Marine and Atmospheric Science. As regards broader impacts, this project would result in a high quality data set that would benefit not only the GEOTRACES community to help them interpret their trace metal and isotope measurements but other scientists involved in organic/inorganic carbon cycle research as well. One graduate student from the University of California, Santa Barbara would be supported and trained as part of this project.