Deuterium Content of Deuterium Depleted Water: 1st Trial

Introduction by Anthony: Here we present some initial findings regarding the nature of deuterium exchange of deuterium depleted water with its environment. Deuterium depleted water experiments involving living organisms are extremely sensitive to deuterium exchange, which is the process of water molecules swapping hydrogens with deuterium atoms. DDW purchased from Sigma is purported to have Because of this, deuterium exchange over time needs to be better understood. Here we present some initial findings that may help to determine this process. We analyzed two samples of deuterium depleted water. One sample was dated January 7, 2012, the other February 16, 2012 which indicate the day the bottles of water were initially opened (exposed to atmosphere). Both samples were stored in a desiccator since the opening date. The samples were analyzed on July 19, 2012. Contained in this fileset you will find the raw (.csv file) and slightly analyzed data (see below). There is also a notation calculator which converts from the machines per mille notation to the pure ratio (which can be easily converted to part per million) and a .pdf that explains per mille notation. Methods and Data by Scott: We measured the 18O/16O and2H/1H ratios of water in two samples of deuterium-depleted water (DDW) using a cavity ring down spectrometer (Picarro). Results are presented in ["HDGS71...calib.xlsx"]. January and February 2012 samples have similar stable oxygen and hydrogen isotope compositions, at roughly δ18O values near -535‰, and δD values close to -1000‰ relative to standard mean ocean water (SMOW; de Wit et al., 1980; Baertschi and Macklin, 1976) which is approximately 1/6420 or 155.76ppm. The δD value of -1000 per mille corresponds to a 2H/1H ratio of zero (within analytical error), suggesting that these waters contain near zero amounts of deuterium. It should be noted at this point that the spectrometer used in these measurements is calibrated to measure natural waters that range in δD values from ~-500 to ~+100, so the instrument is not suited to measure the extremely low deuterium abundances expected in these waters. The oxygen isotope composition of these water samples contains roughly half the concentration of 18O when compared to modern oceans (18O/16O of 0.00092 compared to 0.002005 in SMOW). In δD-δ18O space these waters are shown to lie well “above” the global meteoric water line (Craig, 1961) – a rather unique feature that only occurs under special conditions of moisture recycling in nature (ex. Gat et al., 1994).安东尼引言： 本文呈现了关于贫氘水（deuterium depleted water, DDW）与环境间氘交换特性的初步研究结果。涉及活体生物的贫氘水实验对氘交换过程极为敏感——该过程指水分子中的氢原子与氘原子发生置换反应。从Sigma公司采购的贫氘水据称具有 有鉴于此，我们需要更深入地理解随时间推移发生的氘交换过程，本文即呈现可助力阐明该过程的初步研究结果。 我们对两份贫氘水样本开展了分析：第一份样本的开盖日期为2012年1月7日，第二份为2012年2月16日（水样瓶首次开盖即暴露于大气环境）。两份样本自开盖之日起均储存于干燥器中，并于2012年7月19日完成分析。 本数据集文件包中包含原始数据（.csv格式）与初步处理后的数据（详见下文），同时附带一款换算工具，可将仪器输出的千分比标注换算为纯比值（该比值可便捷转换为百万分比），另有一份阐释千分比符号的.pdf文档。 斯科特的方法与数据： 我们采用腔环衰荡光谱仪（cavity ring down spectrometer, Picarro）对两份贫氘水样本中的¹⁸O/¹⁶O与²H/¹H比值进行了测定。相关结果已收录于"HDGS71...calib.xlsx"文件中。 2012年1月与2月的两份样本具有相似的稳定氧、氢同位素组成：相对于标准海洋水（Standard Mean Ocean Water, SMOW；de Wit等，1980；Baertschi与Macklin，1976），其δ¹⁸O值约为-535‰，δD值接近-1000‰；标准海洋水的²H/¹H比值约为1/6420，即155.76ppm。 δD值为-1000‰时，其²H/¹H比值接近于0（处于分析误差范围内），表明该水样中的氘含量近乎为零。 在此需说明：本研究采用的光谱仪校准范围为δD值约-500‰~+100‰的天然水样，因此该仪器并不适用于测定本研究中贫氘水样本极低的氘丰度。 与现代海洋相比，本研究水样的氧同位素组成中¹⁸O浓度约为现代海洋的一半：标准海洋水的¹⁸O/¹⁶O比值为0.002005，而本研究水样的该比值为0.00092。 在δD-δ¹⁸O坐标体系中，本研究水样的同位素组成显著位于全球大气降水线（Craig，1961）上方，这一独特特征仅在自然界水汽循环的特殊条件下才会出现（例如Gat等，1994）。