The characteristics of the CISE-LOCEAN seawater isotope dataset (δ¹⁸O, δ²H, referred to as δD) are presented (https://doi.org/10.17882/71186; Waterisotopes-CISE-LOCEAN, 2021). This dataset covers the time period from 1998 to 2021 and currently includes close to 8000 data entries, all with δ¹⁸O, three-quarters of them also with δD, associated with a date stamp, space stamp, and usually a salinity measurement. Until 2010, samples were analyzed by isotopic ratio mass spectrometry and since then mostly by cavity ring-down spectroscopy (CRDS). Instrumental uncertainty in this dataset is usually as low as 0.03 ‰ for δ¹⁸O and 0.15 ‰ for δD. An additional uncertainty is related to the isotopic composition of the in-house standards that are used to convert data to the Vienna Standard Mean Ocean Water (VSMOW) scale. Different comparisons suggest that since 2010 the latter have remained within at most 0.03 ‰ for δ¹⁸O and 0.20 ‰ for δD. Therefore, combining the two uncertainties suggests a standard deviation of at most 0.05 ‰ for δ¹⁸O and 0.25 ‰ for δD.For some samples, we find that there has been evaporation during collection and storage, requiring adjustment of the isotopic data produced by CRDS, based on d-excess (δD − 8×δ¹⁸O). This adjustment adds an uncertainty in the respective data of roughly 0.05 ‰ for δ¹⁸O and 0.10 ‰ for δD. This issue of conservation of samples is certainly a strong source of quality loss for parts of the database, and “small” effects may have remained undetected.The internal consistency of the database can be tested for subsets of the dataset when time series can be obtained (such as in the southern Indian Ocean or North Atlantic subpolar gyre). These comparisons suggest that the overall uncertainty of the spatially (for a cruise) or temporally (over a year) averaged data is less than 0.03 ‰ for δ¹⁸O and 0.15 ‰ for δD. However, 18 comparisons with duplicate seawater data analyzed in other laboratories or with other datasets in the intermediate and deep ocean suggest a larger scatter. When averaging the 18 comparisons done for δ¹⁸O, we find a difference of 0.082 ‰ with a standard error of 0.016 ‰. Such an average difference is expected due to the adjustments applied at LOCEAN to saline water data produced either by CRDS or isotope ratio mass spectrometry (IRMS), but the scatter found suggests that care is needed when merging datasets from different laboratories. Examples of time series in the surface North Atlantic subpolar gyre illustrate the temporal changes in water isotope composition that can be detected with a carefully validated dataset.

中文翻译：

---

CISE-LOCEAN 海水同位素数据库 (1998–2021)

介绍了CISE-LOCEAN海水同位素数据集（δ ¹⁸ O、δ ² H，简称δ D）的特征（https://doi.org/10.17882/71186；Waterisotopes-CISE-LOCEAN，2021）。该数据集涵盖了从 1998 年到 2021 年的时间段，目前包括近 8000 个数据条目，所有条目都带有δ ¹⁸ O，其中四分之三还带有δ D，与日期戳、空间戳和通常盐度测量相关。直到 2010 年，样品都通过同位素比质谱法进行分析，此后主要通过腔衰荡光谱法 (CRDS) 进行分析。该数据集中的仪器不确定性通常低至 0.03 ‰ δ ¹⁸ O 和 0.15 ‰δ D. 另一个不确定性与用于将数据转换为维也纳标准平均海水 (VSMOW) 尺度的内部标准的同位素组成有关。不同的比较表明，自 2010 年以来，后者对于δ ¹⁸ O 和δ D的最高保持在 0.03 ‰ 以内。因此，结合这两种不确定性表明δ ¹⁸ O的标准差最高为 0.05 ‰，对于δ的标准差最高为0.25 ‰D.对于一些样品，我们发现在收集和储存过程中存在蒸发，需要根据d -excess ( δ D  −  8× δ ^{18 ) 调整 CRDS 产生的同位素数据}○）。这种调整在各自数据中增加了大约 0.05 ‰ 的δ ¹⁸ O 和 0.10 ‰ 的δ D 的不确定性。样本保存问题无疑是数据库部分质量损失的重要来源，“小”影响可能当可以获得时间序列时（例如在南印度洋或北大西洋亚极地环流中），可以针对数据集的子集测试数据库的内部一致性。这些比较表明，空间（巡航）或时间（一年以上）平均数据的整体不确定性对于δ ¹⁸ O小于 0.03 ‰，对于δ小于 0.15 ‰D. 然而，与在其他实验室分析的重复海水数据或与中海和深海中的其他数据集进行的 18 次比较表明存在更大的分散性。对δ ¹⁸ O进行的 18 次比较进行平均时，我们发现差异为 0.082 ‰，标准误差为 0.016 ‰。由于 LOCEAN 对 CRDS 或同位素比质谱 (IRMS) 产生的盐水数据进行了调整，预计会出现这种平均差异，但发现的分散表明在合并来自不同实验室的数据集时需要小心。北大西洋次极地环流表面的时间序列示例说明了可以使用经过仔细验证的数据集检测到的水同位素组成的时间变化。