The concentration thresholds establishment of nitrogen and phosphorus considering the effects of extracellular substrate-to-biomass ratio on cyanobacterial growth kinetics

Abstract Harmful cyanobacterial blooms have caused serious threat to the sustainable development of freshwater ecosystems due to eutrophication, but there is no consensus on nutrients threshold for controlling cyanobacterial bloom. A Monod-based ratio-dependent model was originally developed to investigate the effects of the extracellular substrate-to-biomass ( Chlorophyll a ) ratio (S ex /X) on the growth kinetics of Cyanobacteria and to determine the concentration thresholds of nitrogen (N) and phosphorus (P) in the form of S ex /X. The results indicated that biomass growth was completely suppressed at S ex /X ≤ 0.21 μg μg −1 for P and S ex /X ≤ 2.82 μg μg −1 for N, which are far lower than the values of most of the eutrophic freshwater lakes. This indicates that in addition to curbing N and P nutrients of eutrophic water, to conduct some biologically mediated changes and to find a suitable environmental fate or a suitable position for excessive N and P nutrients is also of great significance in controlling HABs.