US GEOTRACES Pacific section: Characterizing the redox environment of the eastern tropical Pacific Ocean

从秘鲁到塔希提岛的2013年GEOTRACES东太平洋带样带将穿过一个通常被称为“亚氧”的密集缺氧区；然而，该地区硫酸盐还原的测量表明，由于游离硫化物的存在，它可能具有一些缺氧特征。氧化还原条件影响许多微量元素的溶解度/稳定性，从而影响它们的垂直和水平运输。老道明大学的一位科学家计划分析在巡航期间收集的水样，分析溶解的碘酸盐/碘化物，砷[As(III)/As(V)]，硒[Se(IV， VI)]，颗粒Se(0)，以及纳米到皮摩尔硫化氢形态（总，游离/未络合）。这些测量，连同其他参与者在航行期间确定的硝酸盐/亚硝酸盐、氧化亚氮和铁种类，将用于限制缺氧区内氧化还原条件的范围，评估原位还原与氧化还原物种水平平流的重要性，以及东太平洋隆起热液羽流中不断变化的氧化还原条件。这些数据的可用性也将使其他研究人员能够确定海洋中其他氧化还原敏感微量元素的行为。至于更广泛的影响，除了为GEOTRACES项目的总体目标做出贡献外，该项目还将支持和培训一名博士后、一名研究生和一名本科生。

The 2013 GEOTRACES Eastern Pacific Zonal Transect from Peru to Tahiti will cross an entensive oxygen deficient zone typically described as "suboxic"; however, measurements of sulfate reduction in this region suggest it may have some anoxic characteristics due to the presence of free sulfide. Redox conditions influence the solubility/stability of many trace elements which in turn affects their vertical and horizontal transport. A scientist from Old Dominion University plans to analyze water samples collected during the cruise for dissolved iodate/iodide, arsenic [As(III)/As(V)], selenium [Se(IV, VI), particulate Se(0), and nano- to picomolar hydrogen sulfide speciation (total, free/uncomplexed). These measurements, along with nitrate/nitrite, nitrous oxide, and iron species determined by other participants during the cruise, will be used to constrain the range of redox conditions within the oxygen deficient zone, assess the importance of in-situ reduction versus horizontal advection of the redox species, and the changing redox conditions within the hydrothermal plume of the East Pacific Rise. Availability of this data will also enable other researchers to determine the behavior of other redox sensitive trace elements in the ocean. As regards the broader impacts, in addition to contributing to the overarching goals of the GEOTRACES Program, one postdoc, one graduate student, and one undergraduate student would be supported and trained as part of this project.