Seasonal flooding-drought transformation process of lake sediments lead to changes of dissolved oxygen and redox conditions and the resultant generation of hydroxyl radical (HO^•). To date, information on HO^• formation and its regulators in seasonal lake sediments is largely unexplored. In this study, a total of nineteen sediments were collected from Lake Poyang, China, with the formation and mechanisms of HO^• during the oxygenation process exploring via the incubation experiments, Fe K-edge X-ray adsorption spectroscopy, ultrafiltration, and fluorescent spectroscopy. Results showed that the concentrations of HO^• generated ranged from 3.75 ± 1.13 to 271.8 ± 22.81 μmol kg⁻¹, demonstrating high formation potential and obvious spatial heterogeneity. The yield of HO^• formed was positively correlated with the contents of Fe(II), sedimentary organic carbon, and dissolved organic carbon, showing a general contribution of these reduced substances to HO^• formation. Furthermore, application of Fe K-edge X-ray adsorption spectroscopy revealed the key species of sedimentary Fe-smectite for HO^• formation due to its high peroxidase-like activity. Besides inorganic Fe(II), the sedimentary dissolved organic matters (DOMs) represented an important regulator for HO^• formation, which contributed about 2–11% of the total HO^• generation. Moreover, the DOM-induced formation potential was found to be highly related to the molecular weight distribution that the low molecular weight- (LMW, <1 kDa) fraction exhibited higher HO^• formation potential than the bulk and high molecular weight- (HMW, 1 kDa-0.45 μm) counterparts. In addition, the omnipresent mineral Fe(II)-DOM interaction in sediment matrix exhibited another 2–6% of contribution to the total HO^• production. This study highlighted the importance of contents and species of Fe(II) and DOM in manipulating the HO^• yield, providing new insight into understanding the formation mechanisms of HO^• in the seasonal lake sediment.

湖泊沉积物的季节性洪水-干旱转化过程导致溶解氧和氧化还原条件的变化以及由此产生的羟基自由基（H2O ^•）。迄今为止，关于季节性湖泊沉积物中H2O ^•形成及其调节因素的信息在很大程度上尚未得到探索。本研究共采集鄱阳湖沉积物 19 条，通过孵化实验、Fe K 边缘 X 射线吸附光谱、超滤和荧光光谱等手段探索了氧化过程中 H2O ^•的形成和机制。. 结果显示，产生的 H2O ^•浓度范围为 3.75 ± 1.13 至 271.8 ± 22.81 μmol kg ^-1, 显示出较高的形成潜力和明显的空间异质性。生成的 H2O ^•的产量与 Fe(II)、沉积有机碳和溶解有机碳的含量呈正相关，表明这些还原物质对 H2O ^•形成的总体贡献。此外，铁K边缘X-射线吸收光谱的应用表明沉积的Fe-蒙脱石为HO的主要物种^•形成，由于其高的过氧化物酶样活性。除无机 Fe(II) 外，沉积溶解有机质 (DOMs) 是 H2O ^•形成的重要调节剂，约占 H2O ^•总量的 2-11% ^•一代。此外，DOM诱导形成的潜力被发现是高度相关的分子量分布，所述低分子重量（LMW，<1 kDa）的级分表现出较高的HO ^•比体和高分子重量的形成电位（HMW， 1 kDa-0.45 μm) 对应物。此外，沉积物基质中无处不在的矿物 Fe(II)-DOM 相互作用对总的 H2O ^•产量贡献了另外 2-6% 。本研究强调了 Fe(II) 和 DOM 的含量和种类在操纵 H2O ^•产量方面的重要性，为理解季节性湖泊沉积物中 H2O ^•的形成机制提供了新的见解。