Iron (Fe) plays a key role in elemental cycling at terrestrial–aquatic interfaces by stabilizing carbon (C), phosphorus (P), and nutrient cations through physicochemical associations and by potentially releasing these elements following the reduction of Fe(III) to Fe(II). However, the ecosystem-scale importance of Fe redox cycling and its responses to climate change remain unclear in precipitation-fed peatlands (bogs), C-rich wetlands with very low mineral content. We tested impacts of Fe redox cycling on C and nutrient release in two bogs in northern Minnesota and in Spruce and Peatland Responses Under Changing Environments (SPRUCE), an ecosystem-scale warming experiment. Concentrations of Fe(III) declined from the peat surface to 50 cm depth (31 to 0.5 µmol g⁻¹) and co-occurred with Fe(II) (10 to 30 µmol g⁻¹). Chemical reduction of Fe(III) released C and P from variably saturated (0–30 cm) peat (106–1006 µmol C g⁻¹; 0.6–5 µmol P g⁻¹), and Fe-bound C was similar to previous measurements from upland mineral soils. Concentrations of Fe(II) and dissolved organic carbon (DOC) were strongly (R² = 0.56–0.78) and positively correlated in water samples measured at SPRUCE enclosure outlets and ambient near-surface porewater. Concentrations of Fe(II) also correlated positively with P at warmer SPRUCE temperature treatments and increased with experimental warming, but stabilized at the highest temperature treatments as water depth declined. Although bogs have low total mineral content, mass balance measurements indicated that atmospheric deposition could in principle sustain significant Fe cycling and hydrologic losses in these ecosystems. Overall, Fe redox cycling significantly impacted C and nutrient dynamics in these mineral-poor bogs, contributing to strong correlations between Fe(II) and DOC in water samples. Increased Fe(III) reduction with warmer temperatures will likely promote peatland C and nutrient release, impacting ecosystem C budgets both directly and indirectly by enhancing decomposition and productivity.

铁（Fe）通过物理化学缔合稳定碳（C），磷（P）和营养阳离子并在Fe（III）还原为Fe后潜在释放这些元素，从而在陆-水界面的元素循环中起关键作用（II）。然而，在以降水为食的泥炭地（沼泽），矿物质含量极低的富含C的湿地中，Fe氧化还原循环的生态系统规模重要性及其对气候变化的响应仍不清楚。我们测试了铁氧化还原循环对明尼苏达州北部两个沼泽中碳和养分释放的影响，以及在生态系统规模变暖实验中的变化环境下的云杉和泥炭地响应（SPRUCE）中的影响。Fe（III）的浓度从泥炭表面下降到50 cm深度（31至0.5 µmol g ^-1），并与Fe（II）（10至30 µmol g^-1）。Fe（III）的化学还原从可变饱和（0-30 cm）泥炭（106-1006 µmol C g ^-1 ; 0.6-5 µmol P g ^-1）中释放出C和P ，且与Fe结合的C与以前相似陆地矿物土壤的测量。Fe（II）和溶解有机碳（DOC）的浓度很强（R ² = 0.56-0.78），并且在SPRUCE围网出口和周围近地表孔隙水中测得的水样品中呈正相关。在较暖的SPRUCE温度处理下，Fe（II）的浓度也与P呈正相关，并随着实验温度的升高而增加，但随着水深的降低，在最高温度处理下稳定。尽管沼泽的总矿物质含量低，但质量平衡测量表明，大气沉积原则上可以在这些生态系统中维持明显的铁循环和水文损失。总体而言，Fe氧化还原循环显着影响这些贫矿沼泽中的碳和养分动态，从而导致水样品中的Fe（II）和DOC之间具有很强的相关性。随着温度升高，Fe（III）还原量的增加可能会促进泥炭地C和养分的释放，