Photochemically produced reactive intermediates (PPRIs) formed by sunlight-irradiation of natural photosensitizers play critical roles in accelerating biogeochemical cycles on earth surface. Existing PPRI studies mostly focus on bulk phase reactions (e.g., bulk water), with PPRI processes at the environmental interfaces largely unexplored. Here, we report the wetland soil-water interface (SWI) as a widespread but previously unappreciated hotspot for PPRI productions. Massive productions of four important PPRI species (i.e., triplet-state excited organic matter (³OM*), singlet oxygen (¹O₂), hydrogen peroxide (H₂O₂), and hydroxyl radical (^•OH)) were observed at the SWI. All four PPRI species exhibited higher productions at the SWI than those in bulk water, where ^•OH production was largely elevated by up to one order of magnitude. The enhanced PPRI productions at the SWI were caused by intensified photon absorption and vibrant Fe-mediated redox processes, where the light absorption by less- or non-photoactive soil substances partially offset the enhancement on PPRI productions. Nationwide wetland investigations demonstrate that the SWI was a ubiquitous hotspot for PPRI productions. Simulations on PPRIs-mediated reactions suggest that the enhanced PPRI productions could greatly affect the kinetics and transformation pathways of nutrients and pollutants. Given that the SWI also acts a hotspot for nutrient and pollutant accumulation, incorporating the SWI enhanced PPRI productions into biogeochemical process assessments is pivotal for advancing our understandings on the element cycles and pollutant dynamics in wetlands.

由天然光敏剂的阳光照射形成的光化学产生的反应中间体 (PPRIs) 在加速地球表面的生物地球化学循环中发挥着关键作用。现有的 PPRI 研究主要集中在本体相反应（例如，本体水）上，在环境界面上的 PPRI 过程很大程度上尚未探索。在这里，我们将湿地土壤-水界面 (SWI) 报告为 PPRI 生产的广泛但以前未被重视的热点。四种重要 PPRI 物种（即三重态激发有机物 ( ³ OM*)、单线态氧 ( ¹ O ₂ )、过氧化氢 (H ₂ O ₂ ) 和羟基自由基 ( ^•OH)) 在 SWI 观察到。所有四种 PPRI 物种在 SWI 的产量均高于散装水中的产量，其中^•OH 产量大大提高了一个数量级。SWI 增强的 PPRI 产量是由增强的光子吸收和充满活力的 Fe 介导的氧化还原过程引起的，其中光活性较低或非光活性土壤物质的光吸收部分抵消了 PPRI 产量的增强。全国湿地调查表明，SWI 是 PPRI 生产的普遍热点。对 PPRIs 介导反应的模拟表明，增强的 PPRI 产量可以极大地影响营养物质和污染物的动力学和转化途径。鉴于 SWI 也是养分和污染物积累的热点，