In-situ analysis of sub-nanomolar level of Fe(II) in open-ocean waters

IF 1.8 4区化学 Q3 CHEMISTRY, ANALYTICAL

Analytical Sciences Pub Date : 2024-07-30 DOI:10.1007/s44211-024-00637-0

Hajime Obata, Akira Mase, Toshitaka Gamo, Jun Nishioka, Kei Okamura

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引用次数: 0

Abstract

Iron (Fe) in seawater is an essential micronutrient for marine phytoplankton, and Fe deficiency limits their growth in high-nutrient, low-chlorophyll areas. The bioavailability of Fe for phytoplankton largely depends on its chemical speciation in seawater. In surface water, the reduction of Fe(III) to Fe(II) is an important step in the uptake of Fe by phytoplankton. However, the marine biogeochemical cycle of Fe(II) in the open ocean has not been fully investigated. In oxic open-ocean waters, Fe(II) is rapidly oxidized and exists at sub-nanomolar levels, making it difficult to determine the Fe(II) concentration of seawater. In this study, we applied the flow analytical method of determining the Fe(II) concentration of seawater using luminol chemiluminescence in an in-situ analyzer (geochemical anomaly monitoring system, GAMOS). In the onboard laboratory, we successfully detected sub-nanomolar levels of Fe(II) in seawater using the GAMOS. In the central Indian Ocean, this analyzer was deployed at a depth of 1000 m to determine the Fe(II) concentration in the water column. During deployment, the detection limit (0.48 nM) was insufficient to determine the concentration. Therefore, we need to lower the blank values and enhance the stability of signal of the in-situ analytical method for application to open-ocean seawater samples.

Graphical abstract

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公海水域亚纳摩尔级铁(II)的原位分析。

海水中的铁（Fe）是海洋浮游植物必需的微量营养元素，缺铁会限制浮游植物在高营养、低叶绿素地区的生长。浮游植物对铁的生物利用率在很大程度上取决于其在海水中的化学式。在地表水中，Fe(III) 还原成 Fe(II) 是浮游植物吸收铁的一个重要步骤。然而，对公海中铁（II）的海洋生物地球化学循环尚未进行充分研究。在缺氧的开阔洋水域中，Fe(II) 被迅速氧化，其含量低于纳摩尔，因此很难确定海水中的 Fe(II) 浓度。在本研究中，我们在原位分析仪（地球化学异常监测系统，GAMOS）中采用发光酚化学发光流动分析法测定海水中的铁(II)浓度。在船载实验室，我们利用 GAMOS 成功地检测到海水中铁（II）的亚纳摩尔浓度。在印度洋中部，该分析仪被部署在 1000 米深处，以测定水体中的铁(II)浓度。在部署过程中，检测限（0.48 nM）不足以确定浓度。因此，我们需要降低空白值，提高原位分析方法信号的稳定性，以便应用于公海海水样本。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Analytical Sciences 化学-分析化学

CiteScore

2.90

自引率

18.80%

发文量

232

审稿时长

1 months

期刊介绍： Analytical Sciences is an international journal published monthly by The Japan Society for Analytical Chemistry. The journal publishes papers on all aspects of the theory and practice of analytical sciences, including fundamental and applied, inorganic and organic, wet chemical and instrumental methods. This publication is supported in part by the Grant-in-Aid for Publication of Scientific Research Result of the Japanese Ministry of Education, Culture, Sports, Science and Technology.