The lack of electron donors in oxygen-rich aquatic environments limits the ability of natural denitrification to remove excess nitrate, leading to eutrophication of aquatic ecosystems. Herein, we demonstrate that electron-rich substances in river or lake sediments could participate in long-distance electron rebalancing to reduce nitrate in the overlying water. A microstructure containing Dechloromonas and consisting of an inner layer of green rust and an outer layer of lepidocrocite forms in the sediment-water system through synergetic evolution and self-assembly. The microstructure enables long-distance electron transfer from the sediment to dilute nitrate in the overlying water. Specifically, the inner green rust adsorbs nitrate and reduces the kinetic barrier for denitrification via an Fe(II)/Fe(III) redox mediator. Our study reveals the mechanism of spontaneous electron transfer between distant and dilute electron donors and acceptors to achieve denitrification in electron-deficient aquatic systems.

富氧水生环境中缺乏电子供体限制了自然反硝化去除过量硝酸盐的能力，导致水生生态系统富营养化。在这里，我们证明河流或湖泊沉积物中的富电子物质可以参与长距离电子再平衡，以减少上覆水中的硝酸盐。含有脱氯单胞菌的微结构由内层绿锈和外层纤铁矿组成，在沉积-水系统中通过协同演化和自组装形成。微观结构使电子从沉积物中长距离转移，以稀释上覆水中的硝酸盐。具体来说，内部绿锈吸附硝酸盐并通过 Fe(II)/Fe(III) 氧化还原介质降低反硝化的动力学屏障。我们的研究揭示了远距离和稀电子供体和受体之间自发电子转移的机制，以实现缺电子水生系统中的反硝化。