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

净群落生产量(NCP)和总初级生产量(GPP)是海洋碳循环中的两个关键过程，可以利用三氧同位素(TOI)和O2/Ar的连续测量进行原位定量。不幸的是，与测量和解释TOI和O2/Ar数据有关的两个关键问题仍然没有得到解决，即测量的不确定性和空间变异性。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开展一项相互校准的工作，以解决样本点之间观察到的TOI信号的差异是因为海洋中氧的同位素特征的真正差异，还是它们是测量文物。作为相互校准的一部分，将向实验室分发一套气体、均质水、平衡水和海水样本，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，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，将对平衡器进气质谱仪(EIMS)的连续表层海洋O2/Ar测量和高分辨率TOI采样进行几次网格调查。游轮上将拖着一台浮游生物录像机(VPR-II)，连续测量O2、浮游生物和Seston丰度、温度、盐度、荧光、光合作用有效辐射和水柱上部150米的浑浊程度。将使用各种统计估计器(共光谱、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，将在2至1000公里的尺度上量化空间变异性。至于更广泛的影响，作为这种相互校准工作的结果，将向海洋科学界提供用于确定现场总初级生产力和净碳生产力的经过试验和测试的生物地质化学示踪剂。作为该项目的一部分，一名研究生将得到支持和培训。

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.