Sharpening Geochemical Tools for Assessing Oceanic Biological Production: Exploring the Limits of Oxygen/Argon Ratios and Triple Oxygen Isotopes

净群落产量（NCP）和总初级产量（GPP）是海洋碳循环的两个关键过程，可通过三氧同位素（TOI）和连续测量O2/Ar进行原位量化。不幸的是，测量和解释TOI和O2/Ar数据的两个关键问题仍未解决，即测量不确定性和空间变异性。伍兹霍尔海洋研究所（Woods Hole Oceanographic Institution）的一位科学家计划在全球8个实验室之间开展一项相互校准工作，以确定在不同采样点之间观察到的TOI特征的差异是海洋氧同位素特征真正差异的结果，还是测量结果的伪产物。作为相互校准的一部分，将向实验室分发一套气体、均质水、平衡水和海水样品，以评估测量过程的每个步骤。此外，研究人员将参加一次机会巡航，以检查TOI和O2/Ar比率的空间变异性，并确定这种变异性的原因。为了实现这一目标，将通过平衡器进口质谱仪（EIMS）和高分辨率TOI采样对连续的海洋表面O2/Ar测量进行网格调查。在巡航中，浮游生物视频记录仪（vr - ii）将被拖曳，以连续测量150米以上水柱的氧气、浮游生物和季节丰度、温度、盐度、荧光、光合有效辐射和浊度的分布。将使用各种统计估计器（共谱、小波、概率密度函数）来研究水文特性、生物地球化学特性、O2/Ar比和TOI之间的联系。这项工作将首次将EIMS和VPR-II结合起来，将量化从2000公里到1000公里尺度上的空间变异性。关于更广泛的影响，由于这种相互校准的努力，海洋科学界将获得经过试验和测试的生物地球化学示踪剂，以确定现场的总初级生产力和净碳生产力。作为该项目的一部分，将支持和培训一名研究生。

Net community production (NCP) and gross primary production (GPP) are two key processes in the marine carbon cycle which can be quantified in situ using triple oxygen isotopes (TOI) and continuous measurements of O2/Ar. Unfortunately, two key issues involved with measuring and interpreting TOI and O2/Ar data remain unresolved, namely, measurement uncertainty and spatial variability. A scientist from Woods Hole Oceanographic Institution plans to carry out an intercalibration effort between eight laboratories worldwide to address whether differences in TOI signatures observed between sample sites are results of real differences in the oceanic isotopic signature of oxygen or whether they are measurement artifacts. As part of the intercalibration, a suite of gas, homogenized water, equilibrated water, and seawater samples will be distributed to the laboratories to assess each step of the measurement process. In addition, the researcher will participate in a cruise of opportunity to examine the spatial variability in TOI and O2/Ar ratios and to determine the causes for this variability. To accomplish this goal, several grid surveys of continuous surface ocean O2/Ar measurements from an equilibrator inlet mass spectrometer (EIMS) and high resolution TOI sampling will be conducted. A video plankton recorder (VPR-II) will be towed on the cruise to continuously measure profiles of O2, plankton and seston abundance, temperature, salinity, fluorescence, photosynthetically available radiation, and turbidity in the upper 150 m of the water column. Various statistical estimators (co-spectra, wavelets, probability density functions) will be used to investigate linkages between hydrographic properties, biogeochemical properties, O2/Ar ratios, and TOI. This work, which will be the first to combine an EIMS and the VPR-II, will quantify spatial variability on scales from two to one thousand kilometers.As regards broader Impacts, as a result of this intercalibration effort, tried and tested biogeochemical tracers for determining in situ gross primary productivity and net carbon productivity would be available to the marine sciences community. One graduate student would be supported and trained as part of this project.