Yuan Yuxiang, Ding Cong, Wu Haitao, Tian Xue, Luo Min, Chang Weiyi, Qin Lei, Yang Liang, Zou Yuanchun, Dong Kaikai, Zhu Xiaoyan, Jiang Ming, Otte Marinus L
Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China.
Key Laboratory of Songliao Aquatic Environment, Ministry of Education, Jilin Jianzhu University, Changchun 130118, China.
Fundam Res. 2022 Dec 17;3(6):844-851. doi: 10.1016/j.fmre.2022.12.002. eCollection 2023 Nov.
Dissimilatory iron reduction (DIR) coupled with carbon cycling is increasingly being recognized as an influential process in freshwater wetland soils and sediments. The role of DIR in organic matter (OM) mineralization, however, is still largely unknown in lake sediment environments. In this study, we clarified rates and pathways of OM mineralization in two shallow lakes with seasonal hydrological connectivity and different eutrophic situations. We found that in comparison with the domination of DIR (55%) for OM mineralization in Lake Xiaoxingkai, the contribution of methanogenesis was much higher (68%) in its connected lake (Lake Xingkai). The differences in rates and pathways of sediment OM mineralization between the two lakes were attributed to higher concentrations of carbonate associated iron oxides (Fe) in Lake Xiaoxingkai compared to Lake Xingkai ( = 0.002), due to better deposition mixing, more contributions of terrigenous detrital materials, and higher OM content in Lake Xiaoxingkai. Results of structural equation modeling showed that Fe and total iron content (TFe) regulated 25% of DIR in Lake Xiaoxingkai and 76% in Lake Xingkai, accompanied by a negative effect of TFe on methanogenesis in Lake Xingkai. The relative abundance and diversity of Fe-reducing bacteria were significantly different between the two lakes, and showed a weak effect on sediment OM mineralization. Our findings emphasize the role of iron minerals and geochemical characterizations in regulating rates and pathways of OM mineralization, and deepen the understanding of carbon cycling in lake sediments.
异化铁还原（DIR）与碳循环耦合日益被认为是淡水湿地土壤和沉积物中的一个重要过程。然而，DIR在湖泊沉积物环境中对有机质（OM）矿化的作用在很大程度上仍不清楚。在本研究中，我们阐明了两个具有季节性水文连通性和不同富营养化状况的浅水湖泊中OM矿化的速率和途径。我们发现，与小兴凯湖OM矿化中DIR占主导地位（55%）相比，其连通湖（兴凯湖）中甲烷生成的贡献要高得多（68%）。两个湖泊之间沉积物OM矿化速率和途径的差异归因于小兴凯湖与兴凯湖相比，碳酸根结合铁氧化物（Fe）浓度更高（P = 0.002），这是由于小兴凯湖的沉积混合更好、陆源碎屑物质贡献更多以及OM含量更高。结构方程模型结果表明，Fe和总铁含量（TFe）在小兴凯湖调节了25%的DIR，在兴凯湖调节了76%，同时TFe对兴凯湖的甲烷生成有负面影响。两个湖泊之间铁还原菌的相对丰度和多样性存在显著差异，并且对沉积物OM矿化的影响较弱。我们的研究结果强调了铁矿物和地球化学特征在调节OM矿化速率和途径中的作用，并加深了对湖泊沉积物中碳循环的理解。
