Measurement of fugacity of CO2 in surface water using continuous and discrete sampling methods
Measurement of fugacity of CO2 in surface water using continuous and discrete sampling methods
复制标题
使用连续和离散采样方法测量地表水中二氧化碳的逸度
DOI：
10.1016/0304-4203(93)90202-y
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发表时间：
1993
期刊：
影响因子：
3
通讯作者：
K. Thoning
中科院分区：
文献类型：
--
作者：
R. Wanninkhof;K. Thoning
本文介绍了用于测量表层海水中二氧化碳逸度（或分压）的仪器和方法。为测量开发了两种单独的仪器。一个是在航系统，测量CO2的混合比，X CO2，在顶部空间与表面海水平衡连续泵入24 1平衡室。另一种是离散系统，其中460 ml等分试样的水用120 ml顶空平衡。两种系统都使用非色散红外分析仪作为检测器。在正在进行的仪器中，在接近原位温度下每小时20分钟测量平衡室顶部空间中的平均X CO2。在13节的巡航速度下，这转化为超过8公里的空间平均fCO 2值。正在进行的系统非常适合于绘制大地理区域的地表水逸度。在20° C下分析来自离散仪器的样品。该系统的主要功能是测量地下fCO2值。离散系统也非常适合于确定从相同的等分试样二次采样的CO2和其他（碳）参数的逸度之间的关系。为了计算f CO2在水中的原位条件下从混合比在顶部空间的烧瓶的离散系统，小的碳质量平衡，有时显着，温度校正必须应用。对使用航行中系统和离散系统在南大西洋获得的100个表面值的比较表明，两个系统的pCO2值的平均差异范围为− 4.3 μatm至− 8.6 μatm，取决于温度校正，标准差为4 μatm。差异显示了15 μatm以上的分散性，我们将其归因于离散系统的点样本和正在进行的系统的集成样本之间的不匹配。
Instrumentation and methodology is described which is used for measurement of the fugacity (or partial pressure) of carbon dioxide (f CO 2 or p CO 2) in surface seawater. Two separate instruments were developed for the measurements. One is an underway system which measures the mixing ratio of CO 2, X CO 2, in a headspace in equilibrium with surface seawater continuously pumped into a 24 1 equilibration chamber. The other is a discrete system in which 460 ml aliquots of water are equilibrated with a 120 ml headspace. Both systems use a non-dispersive infrared analyzer as detector. In the underway instrument the average X CO 2 in the headspace of an equilibration chamber is measured at near in-situ temperature over 20 min each hour. At a cruising speed of 13 knots this translates into a space averaged f CO 2 value over 8 km. The underway system is ideally suited for mapping of the surface water fugacity over large geographic regions. Samples from the discrete instrument are analyzed at 20° C. The primary function of the system is for measurement of subsurface f CO 2 values. The discrete system is also well suited for determining the relationship between the fugacity of CO 2 and other (carbon) parameters sub-sampled from the same aliquot. To calculate the f CO 2 in water for in-situ conditions from the mixing ratio in the headspace of the flask of the discrete system, small carbon mass balance and, sometimes significant, temperature corrections have to be applied. Comparison of 100 surface values obtained in the South Atlantic using the underway and discrete systems shows that the average difference of p CO 2 values for the two systems ranges from− 4.3 μatm to− 8.6 μatm, depending on the temperature correction, with a standard deviation of 4 μatm. The differences show scatter of up the 15 μatm which we attribute to a mismatch between the point samples for the discrete system and the integrated samples for the underway system.