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

群落净生产力（NCP）和总初级生产力（GPP）是海洋碳循环中的两个关键过程，可以利用三重氧同位素（TOI）和O2/Ar的连续测量进行原位定量。 不幸的是，涉及测量和解释TOI和O2/Ar数据的两个关键问题仍未得到解决，即测量不确定性和空间变异性。 来自伍兹霍尔海洋研究所的一位科学家计划在全球八个实验室之间进行相互校准，以确定在采样点之间观察到的TOI特征的差异是否是海洋氧同位素特征的真实的差异的结果，或者它们是否是测量人工制品。 作为相互校准的一部分，一套气体、均质水、平衡水和海水样品将被分发到实验室，以评估测量过程的每一步。 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，将进行平衡进气道质谱仪（EIMS）和高分辨率TOI采样的连续表面海洋O2/Ar测量的几个网格调查。 航行中将拖曳一台浮游生物录像机（VPR-II），以连续测量水柱上部150米处的氧气、浮游生物和悬浮物丰度、温度、盐度、荧光、光合有效辐射和浊度的剖面。 各种统计估计（共谱，小波，概率密度函数）将被用来调查水文特性，地球化学特性，O2/Ar比，和TOI之间的联系。 这项工作将是首次将EIMS和VPR-II联合收割机结合起来，将量化从2公里到1 000公里尺度的空间变异性，至于更广泛的影响，由于这项相互校准工作，海洋科学界将可以使用经过试验和测试的生物地球化学示踪剂来确定原地总初级生产力和净碳生产力。 作为该项目的一部分，将支助和培训一名研究生。

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.