Methods for measuring changes in atmospheric O2 concentration and their application in southern hemisphere air
Methods for measuring changes in atmospheric O2 concentration and their application in southern hemisphere air
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DOI：
10.1029/97jd02537
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发表时间：
1998-02-20
影响因子：
4.4
通讯作者：
Shertz, SR
中科院分区：
文献类型：
--
作者：
Keeling, RF;Manning, AC;Shertz, SR
描述了测量大气中O-2浓度变化的方法，重点是气体处理程序。在环境压力下将低温干燥的空气样品收集在5 L玻璃烧瓶中，并对照来自高压铝罐的参比气体进行分析。通过避免整个气体处理系统中的压力和流量变化，将分馏效应降至最低。总体外部再现性约为+/-3.3/mcg，与收集样品和将其储存1年相关的系统误差降低至3/mcg或更小的水平。从高压罐输送的空气的所证明的短期可再现性为+/-1.5/meg，其中当罐被耗尽至低于3500 kPa时，通过表面解吸反应，组成变化至多为5/meg。一套六个参考气体的9年调查显示，没有系统的长期趋势，相对O-2浓度的水平，每兆5。报告介绍了在格里姆角（南纬41度）、麦夸里岛（南纬54度）和南极站（南纬90度）采集的样本的结果。从1991年至1995年的测量发现，南极的O-2浓度平均比格里姆角高3.6+/-1.2微克。这一结果与人们的预期相反，即由于从南大洋吸收O-2，南部高纬度地区的空气中O-2应该耗尽，这可能需要在南极洲附近存在未知的O-2源或意外的大气传输模式。
Methods are described for measuring changes in atmospheric O-2 concentration with emphasis on gas handling procedures. Cryogenically dried air samples are collected in 5 L glass flasks at ambient pressure and analyzed against reference gases derived from high-pressure aluminum tanks. Fractionation effects are minimized by avoiding pressure and flow variations throughout the gas-handling system. The overall external reproducibility is approximately +/-3.3 per meg, with systematic errors associated with collecting samples and with storing them for 1 year reduced to the level of 3 per meg or smaller. The demonstrated short-term reproducibly of air delivered from high-presure tanks is +/-1.5 per meg, with the composition changing by at most 5 per meg by surface desorption reactions as the tank is depleted to below 3500 kPa. A 9-year survey of a suite of six reference gases showed no systematic long-term trends in relative O-2 concentrations to the level of 5 per meg. Results are presented from samples collected at Cape Grim (41 degrees S), Macquarie Island (54 degrees S) and the South Pole Station (90 degrees S). From measurements spanning 1991-1995 it is found that the O-2 concentrations at the South Pole are on average 3.6+/-1.2 per meg higher than at Cape Grim. This result runs contrary to the expectation that the air at high southern latitudes should be depleted in O-2 as a result of O-2 uptake from the Southern Ocean and may require the existence of unknown O-2 sources near Antarctica or unexpected atmospheric transport patterns.