Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China.
Key Laboratory of Northwest Water Resource, Environment and Ecology, MOE, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China; Shaanxi Key Laboratory of Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, People's Republic of China.
Sci Total Environ. 2023 Feb 20;860:160540. doi: 10.1016/j.scitotenv.2022.160540. Epub 2022 Nov 26.
Metalimnetic oxygen minima has been reported in many lakes and reservoirs, but the double metalimnetic oxygen minima (DMOM) is so far poorly understood. In this work, we first reported DMOM in the Sanhekou Reservoir, and investigated its formation reason and influence on the bacterial community composition (BCC). The results showed that the two anaerobic layers were formed in DMOM, located at 10 m and 45 m approximately. The rapid water storage process and thermal stratification resulted in the double metalimnions. Algal accumulation, decomposition and oxygen consumption in these regions during the sedimentation process eventually leaded to the formation of DMOM. Water temperature and DO gradients made outstanding contributions to the spatiotemporal environmental heterogeneity and significantly affected the BCC. Depending on the distribution of dissolved oxygen (DO), the storage process could be divided into three periods: DMOM, single MOM period and mixed period. Exiguobacterium and Ralstonia were dominated in DMOM due to the soil discharge and plant decomposition. Besides, BCC presented the largest vertical difference in DMOM and existed the interlayer-similar phenomenon (BCC in the two anaerobic layers were more similar). This study explained the formation of DMOM and its influence on BCC, which was helpful to understand the response of BCC to the storage process and unique DO structure in a moderate eutrophication reservoir.
双氧分层现象在许多湖泊和水库中都有报道，但目前对其了解甚少。本研究首次在三岔口水库发现了双氧分层现象，并对其形成原因及其对细菌群落组成（BCC）的影响进行了研究。结果表明，双氧分层现象中存在两个厌氧层，分别位于约 10 m 和 45 m 处。快速的蓄水过程和热力分层导致了双氧分层的形成。在沉积过程中，藻类的积累、分解和耗氧作用最终导致了双氧分层现象的形成。水温梯度和 DO 梯度对时空环境异质性有显著影响，并显著影响 BCC。根据溶解氧（DO）的分布，蓄水过程可分为三个阶段：双氧分层期、单氧分层期和混合期。由于土壤排放和植物分解，极端芽孢杆菌属和罗尔斯通氏菌属在双氧分层期占主导地位。此外，BCC 在双氧分层期表现出最大的垂直差异，并存在层间相似现象（两个厌氧层中的 BCC 更为相似）。本研究解释了双氧分层现象的形成及其对 BCC 的影响，有助于理解 BCC 对中营养化水库蓄水过程和独特 DO 结构的响应。
