Sampling and onboard analytical methods for determining subnanomolar concentrations of zinc in seawater
Sampling and onboard analytical methods for determining subnanomolar concentrations of zinc in seawater
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DOI：
10.1002/lom3.10004
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发表时间：
2015-01
期刊：
影响因子：
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通讯作者：
Taejin Kim;H. Obata;T. Gamo;J. Nishioka
中科院分区：
文献类型：
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作者：
Taejin Kim;H. Obata;T. Gamo;J. Nishioka
锌（Zn）是海洋中浮游植物和细菌必需的微量营养元素。然而，由于实验室和研究船中Zn的普遍存在，用于Zn测量的海水样品非常容易受到污染。为了确定一个潜在的锌污染的问题，在研究巡航到亚北极北太平洋，我们比较了三个操作采样方法的微量锌在海水中。酸洗Niskin‐X采样器：（1）部署在从船舶右舷发射的电导率-温度-深度转盘多通道系统（CTD‐CMS）上，（2）连接到从船舶船尾降下的Kevlar线上，以及（3）连接到从右舷位置降下的Ti线上。对于≤400 m的样品，Kevlar线液压铸件的锌污染是有问题的，因为锌被用作船舶螺旋桨轴和海水冷却系统管道的牺牲阳极。在深水沃茨，一致的锌浓度被发现使用三种不同的采样方法。基于CTD‐CMS的清洁海水采样和船上分析方法，获得了溶解Zn的垂直剖面。这些配置文件进行了比较，硅在亚北极北太平洋。在浅水沃茨，Zn和Si的浓度均呈现明显的东西向梯度。
Zinc (Zn) is an essential micronutrient for bacteria and phytoplankton in the ocean. However, seawater samples for Zn measurements are highly prone to contamination due to the ubiquity of Zn in laboratories and research vessels. To identify a potential Zn contamination problem during a research cruise to the subarctic North Pacific, we compared three operational sampling approaches for trace Zn in seawater. Acid‐cleaned Niskin‐X samplers were: (1) deployed on a conductivity–temperature‐depth carousel multisampling system (CTD‐CMS) launched at the vessel's starboard side, (2) attached to a Kevlar wire lowered at the vessel's stern, and (3) attached to a Ti wire lowered from a starboard position. Zn contamination in the case of Kevlar wire hydrocasts was problematic for samples from ≤400 m because Zn is used as a sacrificial anode for the ship's propeller shaft and for the pipes of the seawater cooling system. In deep waters, consistent Zn concentrations were found using the three different sampling methods. Based on the clean seawater sampling with CTD‐CMS and the onboard analytical method, vertical profiles of dissolved Zn were then obtained. These profiles were compared with those of Si in the subarctic North Pacific. Both Zn and Si concentrations showed a clear west–east gradient in shallow waters.