GEOTRACES: Intercalibration of Nitrate Isotope Analyses and Sample Preservation Techniques

海洋环境中硝酸盐d15N和d18O测量的空间复盖面有限。将这些同位素作为关键参数包括在即将到来的GEOTRACES计划中，为收集和分析来自世界海洋的大量样本提供了一个独特的机会，并进一步了解了硝酸盐同位素的空间梯度及其记录的过程。然而，在这个项目中，来自世界各地的不同实验室将利用自己的采样、保存、分析和校准技术来测量这些同位素。为了避免由于任何这些成分的差异而产生分析偏差的可能性，伍兹霍尔海洋研究所的一位科学家召集了一个令人印象深刻的国家和国际实验室小组，参与即将到来的GEOTRACES相互校准工作。在2008年和2009年夏季进行的GEOTRACES间校准巡航期间，将对不同的样品收集和保存测试进行评估，对跨越海水中硝酸盐浓度和d15N自然范围的各种校准间样本进行分析，确定硝酸盐同位素比率，并对结果进行评估，以确保在相互校准工作的参与者之间获得一致的分析结果。在更广泛的影响方面，将制定一项收集、储存、分析和校准海水硝酸盐同位素的议定书，并向科学界提供。

The spatial coverage of nitrate d15N and d18O measurements in the marine environment is limited. Inclusion of these isotopes as key parameters in the upcoming GEOTRACES program provides a unique opportunity to collect and analyze numerous samples from the world ocean's and further our understanding of the spatial gradients in nitrate isotopes and the processes they record. However, during this program, different laboratories from around the world would utilize their own sampling, preservation, analysis, and calibration techniques to measure these isotopes. To avoid the potential for analytical offsets due to differences in any of these components, a scientist from Woods Hole Oceanographic Institution has assembled an impressive group of national and international laboratories to participate in the upcoming GEOTRACES intercalibration effort. During the GEOTRACES intercalibration cruises in summer 2008 and 2009, different sample collection and preservation tests would be evaluated, a variety of intercalibration samples that span the natural range of nitrate concentration and d15N in seawater would be analyzed, the nitrate isotope ratio would be determined, and the results evaluated to ascertain that consistent analytical results are obtained amongst the participants in the intercalibration effort. In terms of broader impacts, a protocol for the collection, storage, analysis, and calibration of seawater nitrate isotopes would be established and made available to the science community.