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

2013年GEOTRACES从秘鲁到塔希提岛的东太平洋带状样带将穿越一个通常被描述为“亚氧”的严重缺氧区;然而，该地区硫酸盐还原的测量结果表明，由于存在游离硫化物，该地区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，这反过来又影响它们的垂直和水平运输。 Old自治领大学的一位科学家计划分析航行期间收集的水样，以确定溶解的碘酸盐/碘化物、砷[As（III）/As（V）]、硒[Se（IV，VI）]、微粒Se（0）和纳至皮摩尔的硫化氢形态（总的、游离的/未络合的）。 这些测量值，沿着与巡航期间其他参与者确定的硝酸盐/亚硝酸盐、一氧化二氮和铁物种一起，将用于限制缺氧区内氧化还原条件的范围，评估氧化还原物种的原位还原与水平平流的重要性，以及东太平洋海隆热液羽流内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，除了有助于GEOTRACES计划的总体目标，一名博士后，一名研究生和一名本科生将作为该项目的一部分得到支持和培训。

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.