Key Laboratory of Agro-ecological Processes in Subtropical Region, The Chinese Academy of Sciences, Changsha 410125, China; Dongting Lake Station for Wetland Ecosystem Research, Institute of Subtropical Agriculture, The Chinese Academy of Sciences, Changsha 410125, China; University of Chinese Academy of Sciences, Beijing 100049, China.
School of Resources and Environmental Engineering, Anhui University, Hefei 230601, China; Key Laboratory of Agro-ecological Processes in Subtropical Region, The Chinese Academy of Sciences, Changsha 410125, China; Dongting Lake Station for Wetland Ecosystem Research, Institute of Subtropical Agriculture, The Chinese Academy of Sciences, Changsha 410125, China.
Sci Total Environ. 2022 Jun 25;827:154225. doi: 10.1016/j.scitotenv.2022.154225. Epub 2022 Mar 2.
Changes in flood regimes, floodwater quality, and macrophyte types may affect sediment characteristics post-flooding. However, few studies have attempted to unravel their complex influences in floodplain wetlands. From 2011 to 2020, the physical and chemical properties of surface layer sediment pre- and post-flooding was investigated through field surveys in the Dongting Lake wetland. Results indicated that the pre-flooding soil total phosphorus (TP) and total nitrogen (TN) exhibited an increasing trend during 2011-2020. Soil TP increased post-flooding relative to that pre-flooding. The changes in TN, sediment organic matter (SOM), sediment moisture content (SMC), and sediment bulk density (SBD) fluctuated over the years. The best-fitting multi-regression model demonstrated that the changes in sediment variables post-flooding showed a parabolic trajectory along the inundation duration (ID), except for SMC. Changes in soil properties post-flooding were negatively correlated with ID for sediment with a low IDs (<148 days). Meanwhile, changes in soil properties post flooding were positively correlated with ID for sediment with a high IDs (>193 days). Changes in SBD and SOM post-flooding were positively influenced by the TP content in the floodwater. These findings indicate that changes in the flooding regime, and water quality generated by anthropogenic disturbances such as the Three Gorges Dam significantly affect sediment properties, and subsequently influence the ecological functions of the Dongting Lake wetland.
洪水过程、洪水水质和大型植物类型的变化可能会影响洪水后的沉积物特征。然而，很少有研究试图阐明它们在洪泛湿地中的复杂影响。2011 年至 2020 年，通过对洞庭湖湿地的实地调查，研究了洪水前后表层沉积物的物理和化学性质。结果表明，2011-2020 年间，洪水前土壤总磷（TP）和总氮（TN）呈增加趋势。与洪水前相比，洪水后土壤 TP 增加。TN、沉积物有机质（SOM）、沉积物含水量（SMC）和沉积物容重（SBD）多年来波动。最佳拟合多元回归模型表明，除 SMC 外，洪水后沉积物变量的变化沿洪水持续时间（ID）呈抛物线轨迹。洪水后土壤性质的变化与 ID 呈负相关，对于 ID 较低的沉积物（<148 天）。同时，洪水后土壤性质的变化与 ID 呈正相关，对于 ID 较高的沉积物（>193 天）。洪水后 SBD 和 SOM 的变化受到洪水水中 TP 含量的正向影响。这些发现表明，洪水过程的变化以及三峡大坝等人为干扰产生的水质显著影响沉积物特性，进而影响洞庭湖湿地的生态功能。
