Effects of dam building on NO-producing and NO-reducing community structures in river sediments and the associated NO emission potential.

Dam construction is regarded as the greatest anthropogenic disturbance in aquatic ecosystems, and it promotes denitrification, through which large NO emissions occur. However, the effect of dams on NO producers and other NO-reducing microorganisms (especially for nosZ II), and the associated denitrification rates remain poorly understood. This study systematically investigated the spatial variation of potential denitrification rates in dammed river sediments in winter and summer and the microbial processes driving NO production and reduction.

Effects of dam building on the occurrence and activity of comammox bacteria in river sediments and their contribution to nitrification.

The recent discovery of complete ammonia oxidizers (comammox) has fundamentally changed our understanding of nitrification. However, studies on the occurrence and activity of comammox bacteria and their contribution to nitrification remain unclear. Here, we investigated the abundance, activity, and diversity of comammox bacteria and their contribution to nitrification in sediments from dammed rivers in winter and summer.