GEOMAR Helmholtz Centre for Ocean Research Kiel , Marine Biogeochemistry, Düsternbrooker Weg 20, 24105 Kiel, Germany.
Environ Sci Technol. 2013 Sep 17;47(18):10257-65. doi: 10.1021/es4016603. Epub 2013 Aug 22.
Manganese (Mn) is a required element for oceanic phytoplankton as it plays a critical role in photosynthesis, through its unique redox chemistry, as the active site in photosystem II, and in enzymes that act as defenses against reactive oxygen species (ROS), most notably for protection against superoxide (O2(-)), through the action of superoxide dismutase (SOD), and against hydrogen peroxide (H2O2) via peroxidases and catalases. The distribution and redox speciation of Mn in the ocean is also apparently controlled by reactions with ROS. Here we examine the connections between ROS and dissolved Mn species in the upper ocean using field and laboratory experimental data. Our results suggest it is unlikely that significant concentrations of Mn(III) are produced in the euphotic zone, as in the absence of evidence for the existence of strong Mn(III) ligands, Mn(II) reacts with O2(-) to form the short-lived transient manganous superoxide, MnO2(+), which may react rapidly with other redox species in a manner similar to O2(-). Experiments with the strong Mn(III) chelator, desferrioxamine B (DFB), in seawater indicated that the Mn(III) species are unlikely to form, as formation of the precursor Mn(II) complex is hindered due to the stability of the Ca complex with DFB.
锰 (Mn) 是海洋浮游植物所必需的元素，因为它通过其独特的氧化还原化学特性、作为光系统 II 中的活性位点以及在作为抵御活性氧 (ROS) 的防御酶中的作用，在光合作用中起着关键作用，尤其是通过超氧化物歧化酶 (SOD) 对超氧化物 (O2(-)) 的保护作用，以及通过过氧化物酶和过氧化氢酶对过氧化氢 (H2O2) 的保护作用。Mn 在海洋中的分布和氧化还原形态也显然受到与 ROS 反应的控制。在这里，我们使用现场和实验室实验数据来研究海洋上层中 ROS 和溶解 Mn 物种之间的联系。我们的结果表明，在光区不太可能产生大量的 Mn(III)，因为在没有强 Mn(III)配体存在的证据的情况下，Mn(II)与 O2(-)反应形成短暂存在的瞬态亚锰过氧化物，MnO2(+)，它可能以类似于 O2(-)的方式与其他氧化还原物质快速反应。在海水中使用强 Mn(III)螯合剂去铁胺 B (DFB) 的实验表明，Mn(III)物种不太可能形成，因为由于 DFB 与 Ca 形成稳定的配合物，Mn(II)配合物的形成受到阻碍。
