不同水动力条件下间歇微孔曝气对河道底质微生物群落的影响

微孔曝气技术被广泛运用于城市河道治理中,在间歇曝气过程中和曝气停止后微生物群落结构和功能的变化仍不明晰。采用室内模拟试验探究了曝气5 d再静置10 d后,不同水动力条件下水体污染物浓度变化过程以及底质微生物群落结构和功能的响应规律。结果表明:不同水动力条件下间歇曝气过程中和曝气停止后DO均能维持较高水平,但水体污染物浓度在曝气停止后短期内均出现显著性增加,但低流速(v=0.24 m/s)条件下污染物浓度上升最为缓慢。从微生物群落组成方面来看,该现象是由于曝气停止静置10 d后,与有机物代谢相关的氢噬菌属等菌属仅在低流速条件下可成为优势菌属,使得该流速水体中有机物更易降解,污染物浓度上升更为缓慢。从微生物群落功能方面来看,在曝气停止静置10 d后,富营养化水体中的能量代谢、辅酶和维生素代谢等代谢通路更多存在于静止和高流速(v=0.93 m/s)条件下的水体中,解释了这2种流速条件下污染物浓度更高的现象。该研究结果可为通过曝气手段持久性改善河道水质提供理论依据。

EFFECTS OF INTERMITTENT MICROPOROUS AERATION ON MICROBIAL COMMUNITIES IN URBAN RIVER SEDIMENTS UNDER DIFFERENT HYDRODYNAMIC CONDITIONS

Microporous aeration technology is widely used in urban river management. The changes in the structure and function of the microbial community during the intermittent aeration process and after aeration stopped are still unclear. Indoor simulation experiments were used in this paper to investigate the changing process of pollutant concentration in water bodies under different hydrodynamic conditions, as well as the response law of the structure and function of the sedimentary microbial community from the beginning of aeration to 5 days after aeration, and then 10 days. The results showed that: the DO could be maintained at a high level under different hydrodynamic conditions, both during the intermittent aeration process and after the aeration stopped, but the water pollutant concentration rose significantly after aeration stopped, and the pollutant concentration rose the most slowly under the low flow rate condition (v=0.24 m/s). In terms of microbial community composition, this phenomenon resulted from the genus Hydrogenophaga and Novosphingobium, which were related to organic matter metabolism, became the dominant genus only under the condition of low flow rate after aeration stopped and stood still for 10 days, making the organic matter in the water body more prone to degradation, and the pollutant concentration rise more slowly. In terms of microbial community function, after aeration stopped for 10 days, metabolic pathways such as energy metabolism, coenzyme and vitamin metabolism, which were usually more common in eutrophic water bodies, were more present in water bodies under static and high flow rate (v=0.93 m/s). That explained the higher pollutant concentration under these two flow rates. The research results can provide a theoretical basis for persistently improving river water quality through intermittent microporous aeration.