Specific Determination of Trace Amount of Iron in Different Oxidation States in Coastal Sea Water to Investigate the Sources of Sea Desert

特异性测定沿海海水中不同氧化态痕量铁探讨海漠来源

• 批准号: 18550067
• 负责人: MATSUOKA Shiro
• 金额: $ 1.52万
• 依托单位: Niigata University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2006
• 资助国家: 日本
• 起止时间: 2006 至 2007
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-18550067/
• 关键词: coastal sea water; trace amount of iron; speciation; solid phase spectrometry; sea desert; on-site analysis; 海水; 鉄; 酸化状態別定量

Recently "sea desert" has been widely observed in the coastal region in Japan. One of the source of this sea desert is considered to be the decrease of the iron complex with organic compounds which is supplied from the soil to coastal sea water through rivers. However, the reliable data which can be applied to discuss on the source of sea desert have not been well reported because of the difficulty in determining the concentrations of trace amounts of iron in different oxidation state present in coastal sea water. In this study we have developed the high sensitive and selective speciation method using solid phase spectrometry for ultra trace iron in coastal sea waters to investigate the causes of sea desert which gives serious damages to inshore fisheries in Japan. The results obtained by this project are listed below.1) The complex of [Fe(phen)3]2+ was strongly adsorbed on cation-exchange resin phase. The distribution ratio was in the 104 order and it was not affected by the ionic strength of sample solutions.2) By using a small lens attached on the light detector window of a spectrophotometer, scattered light at the surface of ion-exchange resin beads could be effectively collected and focused at the light detector windows. This greatly reduced the back ground light attenuance of solid phase and made it possible to measure the light absorption of solid phase even at 1 cm light path length.3) One of the features of the proposed method is that the proportional increases of sensitivity can be easily attained by the increase in the sample volume at a constant sold phase volume. In the case of using 0.25 g ion-exchange resin, the sensitivity could be increased by increasing the sample volume at least up to 400 cm3. The detection limit was 10 ng dm-3 when using 400 cm3 sample solutions.4) Recovery test was also applied and good recoveries around 100% were obtained.

最近，日本沿海地区出现了广泛的海上沙漠现象。海洋沙漠的来源之一被认为是从土壤中通过河流向沿海海水供应的有机化合物铁络合物的减少。然而，由于近海海水中不同氧化态的痕量铁的浓度难以测定，因此，能够用来讨论海沙漠来源的可靠数据还没有很好的报道。本研究建立了固相光谱分析近海超痕量铁的高灵敏、高选择性的形态分析方法，以探讨严重危害日本近海渔业的海洋荒漠的成因。研究结果如下：1)[Fe(Phen)_3]~(2+)络合物在阳离子交换树脂相上有较强的吸附作用。分配比为104量级，不受样品溶液离子强度的影响。2)通过在分光光度计的光检测器窗口上安装一个小透镜，可以有效地收集离子交换树脂微珠表面的散射光，并将其聚焦在光检测器窗口。这大大降低了固相的背景光衰减，使得即使在1 cm的光路长度下也可以测量固相的光吸收。3)该方法的一个特点是，在固定销售相体积的情况下，通过增加样品体积可以很容易地实现灵敏度的成比例增加。在使用0.25g离子交换树脂的情况下，将样品体积至少增加到400cm3，可以提高灵敏度。当使用400 cm~3样品溶液时，检出限为10 ng dm~(-3)。4)还进行了回收率试验，回收率在100%左右。