The formation of double metalimnetic oxygen minima in a drinking water reservoir and its influence on bacterial community

• Published in: The Science of the total environment 2023-02, Vol.860, p.160540-160540, Article 160540
• Main Authors: Yang, Meng, Wen, Gang, Cao, Shuangli, Li, Kai, Huang, Tinglin, Ji, Gang, Wang, Sihan, Xue, Ruikang, Cao, Ruihua
• Format: Article
• Language: English
• Subjects: Algal bloom; Bacteria; Bacterial community composition; China; Double metalimnetic oxygen minima; Drinking Water; Eutrophication; Oxygen - analysis; Reservoir; Temperature; Thermal stratification; Water Quality
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.160540

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. [Display omitted] •The double metalimnetic oxygen minim (DMOM) was first reported.•The formation of DMOM was caused by the blocking effect of the double metalimnions on algae deposition.•DMOM drove environmental heterogeneity and impacted on BCC significantly.•In DMOM, DO had the greatest effect on BCC and caused the interlayer-similar phenomenon.