作者：Huang, R., Guo, J., Peng, K., Cai, C., Huang, X., Wu, Q. & Liu, J.

Urban artificial lake sediments play crucial role in organic carbon (OC) fixation for cities. However, the regulatory mechanism on sedimentary OC fixation by water temperature (WT) changes is still unclear. This study investigated the water qualities, organic carbon components, the microbial metabolism and iron (Fe) fractions of five lakes in summer and winter. Results revealed that high temperature group (HT) exhibited 1.5-2.5 times higher average contents of total organic carbon (TOC), particulate organic carbon (POC), mineral-associated organic carbon (MAOC) and Fe-bound organic carbon (Fe-OC), comparing to the winter low-temperature (LT) group. The average MAOC/TOC ratio in the HT group and LT group was 65 % and 46 %, respectively, indicating that WT played a dominant role in stable OC formation. Analysis of metabolomics indicated predominant microbial carbon dioxide fixation pathway was transformed from photosynthetic autotrophy to chemoautotrophy, accompanied by an increased relative abundance of the associated regulatory enzymes as WT rose. Furthermore, elevated temperatures promoted a significant increase in the Fe reduction rate, activation degree, and complexation degree of sediments, thereby also facilitating the formation of stable OC. In conclusion, high temperature triggered the "microbe-iron-carbon" cascade by increasing chlorophyll-a concentrations and reducing dissolved oxygen and transparency, which may enhance the sedimentary carbon fixation potential. These findings provide a theoretical basis for optimizing the ecological design and management strategies to enhance carbon sink of urban artificial lakes.

城市人工湖泊沉积物在城市有机碳（OC）固定中发挥着关键作用，然而水温（WT）变化调控沉积物有机碳固定的机制仍不清楚。研究调查了5个城市人工湖泊在夏季与冬季的水质、有机碳组分、微生物代谢及铁（Fe）赋存形态。结果显示，与冬季低温组（LT）相比，高温组（HT）的总有机碳（TOC）、颗粒态有机碳（POC）、矿物结合态有机碳（MAOC）与铁结合态有机碳（Fe-OC）的平均含量高出1.5-2.5倍。HT组与LT组的MAOC/TOC平均比值分别为65%与46%，表明水温在稳定有机碳形成中起主导作用。代谢组学分析表明，随着水温升高，微生物CO₂固定的主导途径由光合自养转变为化能自养，相关调节酶的相对丰度随之增加。此外，升温显著提高了沉积物的铁还原速率、活化度与络合度，进而也促进了稳定有机碳的形成。综上所述，高温通过提高叶绿素a浓度、降低溶解氧与透明度，触发了“微生物—铁—碳”级联过程，从而可能增强沉积物的固碳潜势。这些发现为优化城市人工湖泊的生态设计与管理策略、提升其碳汇功能提供了理论依据。

（来源：Water Research 2026  DOI: 10.1016/j.watres.2026.125594）