Bioavailability of iron in the North Pacific and its adjacent area

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K12309
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 63010:Environmental dynamic analysis-related
• Research Institution: Nagasaki University
• Principal Investigator: Kondo Yoshiko 長崎大学, 水産・環境科学総合研究科(水産), 准教授 (40722492)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 鉄 / 植物プランクトン / 二価鉄 / 光化学反応 / 生物利用能 / 酸化還元 / 北太平洋 / 有機配位子

Outline of Final Research Achievements

In order to understand the marine biogeochemical cycle of iron and its bioavailability, this study focused on Fe(II), which has a high bioavailability among the chemical forms of iron in seawater. It was carried out with the aim of verifying the hypothesis that the behavior of Fe(II) is controlled by the environment such as temperature, pH, and so on, and Fe(II) dynamics affect phytoplankton biomass. Our results showed that Fe(II) is produced through photochemical reactions in the surface water during the daytime. In the North Pacific, the photoirradiation-induced Fe(II) formation/dissipation rates varied between sea areas. This was attributed to differences in water temperature, pH, and photochemical reactivity of organic ligands in natural seawater. In addition, it was considered that the difference in Fe(II) production rate affected the biological productivity in the North Pacific.

Free Research Field

海洋生物地球化学

Academic Significance and Societal Importance of the Research Achievements

海洋では、一次生産性が海域によって異なり、栄養物質の挙動の違いがその鍵を握ると考えられている。鉄は生物活動に不可欠な微量金属元素だが、海水中には難溶で、その循環機構は明らかでない。本研究の結果は、海洋一次生産を支える植物プランクトンによる鉄利用機構や海域間での生物生産性の違いについての理解を促進するものである。本研究で見られた「水温やpH、海水中の有機物の組成は鉄の生物利用効率に影響を与える」という結果は、地球温暖化に伴う海洋環境変化は鉄の生物利用能の変化をもたらす可能性を示している。