Assessment of algae and greenhouse gases in different reservoirs worldwide by reactor model

The increasing concentration of greenhouse gases (GHGs) in the atmosphere is a great challenge to the development of human society. GHGs emissions in reservoirs have been a hot topic of freshwater GHG research for nearly two decades. The factors influencing the emissions of GHGs from reservoirs are intricate. From a hydrological perspective, the fundamental reservoir characteristics, such as water depth, area and perimeter, have an impact on the total GHGs emissions. From a biological perspective, GHGs emissions from the reservoir could be impacted by bacteria, algae, and other microorganisms because of their physiological metabolism. Here, we classified the global reservoirs as continuous stirred tank reactor (CSTR), general reactor (GR), and plug flow reactor (PFR) reservoirs by referring to the simulation graphics and dynamics theory of biochemical reactors. In addition, we examined the connection between algal blooms and GHGs emissions in light of algae degradation and hydrodynamic factors like the water flow rate, water residence time (WRT), and thermal structure of the water column. The results indicated that GHGs emissions have a negative relationship with algae in the GR-reservoirs, while the algae could promote GHGs emissions in the PFR-reservoirs or CSTR-reservoirs. The reactor classification method was introduced into the Three Gorges Reservoir (TGR), and the spatial heterogeneity of algal bloom-GHGs coupling in different tributaries of the TGR was explained, which proved that the reactor classification method is reliable.