A determination of atmospheric helium, neon, argon, krypton, and xenon solubility concentrations in water and seawater
A determination of atmospheric helium, neon, argon, krypton, and xenon solubility concentrations in water and seawater
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DOI：
10.1016/j.marchem.2019.03.007
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发表时间：
2019-04-20
期刊：
影响因子：
3
通讯作者：
Cahill, K. L.
中科院分区：
文献类型：
--
作者：
Jenkins, W. J.;Lott, D. E., III;Cahill, K. L.
我们已经测定了蒸馏水和海水中氦、氖、氩、氪和氙气的浓度，这些水和海水与潮湿的海洋空气在一个大气中平衡，温度范围从接近冰点到大约35摄氏度，盐度范围从0到大约39.5 PSS78。总共，我们在34种不同的温度和盐度组合下进行了74组惰性气体测量。这些实验包括35对重复的样本，这些样本来自35个独立的平衡，而这些平衡又有三对重复平衡在接近相同的温度下运行。我们将结果拟合成一个八参数函数，该函数类似于通常用于计算这些气体在环境水体中的溶解度平衡浓度的函数。根据分析精度、与二级大气标准比较的重现性、重复样品的重现性和重复平衡的重现性的估计，我们估计该函数可以预测该范围内特定温度和盐度下的平衡浓度，总体精度为0.10%或更高。这包括与用于拟合8参数平滑函数的内插和分析误差相关的回归统计数据。根据我们对近年来空气标准的完整性和交叉校准的信心和经验，所有气体的总体系统不确定度为0.15%。由于我们的方法是使用这些惰性气体的假定和明确的大气丰度进行校准的，因此大气丰度的任何后续不确定性都会在测定中抵消，特别是当海洋测量使用海洋空气作为主要标准时。此外，在环境大气丰度下的测量避免了使用类似于1大气压纯惰性气体的任何潜在的共溶解引起的偏差，正如在大多数以前的研究中所做的那样。我们将这些决定与其他人在过去所做的决定进行了比较，发现这些结果存在轻微但显著的系统差异。
We have determined the concentrations of atmospheric helium, neon, argon, krypton, and xenon in distilled water and seawater equilibrated with moist marine air at one atmosphere over a temperature range from near freezing point to approximately 35 degrees C and a salinity range of zero to roughly 39.5 PSS78. In all, we made 74 sets of noble gas measurements at 34 distinct temperature and salinity combinations. The experiments included 35 replicate pairs of samples drawn from 35 separate equilibrations, which in turn had three pairs of repeat equilibrations run at close to identical temperatures. We fit the results to an eight-parameter function similar to one commonly used to compute solubility equilibrium concentrations of these gases for environmental waters. Based on an estimate of analytical accuracy, reproducibility of the comparison with secondary atmospheric standards, replicate sample reproducibility, and reproducibility of the repeat equilibrations, we estimate this function to predict equilibrium concentrations at a particular temperature and salinity within this range to overall precisions 0.10% or better. This includes the regression statistics associated with interpolation and analytical errors for fitting the 8-parameter smoothing function. There is an overall systematic uncertainty of 0.15% for all gases, based on our confidence in and experience with the integrity and cross-calibration of our air standards over recent years. Because our methods are calibrated using assumed and explicit atmospheric abundances of these noble gases, any subsequent uncertainties in atmospheric abundances cancel out in the determination, particularly when the oceanographic measurements utilize marine air as a primary standard. Furthermore, measurement at ambient atmospheric abundances avoids any potential co-solvency induced biases introduced by using similar to 1 atm pure noble gases, as has been done in most previous studies. We compare these determinations to those made by others in the past and find modest but significant systematic differences with those results.