Release behavior of odor contaminants derived from Microcystis aeruginosa in rivers and a non-strict anaerobic aqueous system

Data were collected and reviewed to assess the odorous contaminant status of drinking water sources for Hangzhou City, China. β-Cyclocitral, β-ionone, dimethyl trisulfide, 2-methylisoborneol, and geosmin were targeted odorants. Results indicate that β-cyclocitral was the main contaminant in source waters as it was most frequently detected and occurred at higher concentrations compared to other odorants. Cyanophyta, including Oscillatoria, Microcystis, and Anabaena, were detected in river source waters. The origin of β-cyclocitral was also investigated in the laboratory by simulated non-strict anaerobic experiments using a prevalent species, Microcystis aeruginosa. Under non-strict anaerobic conditions, M. aeruginosa released primarily β-cyclocitral and β-ionone. Correlation of β-cyclocitral and cyanobacteria counts in the laboratory provide an explanation for high β-cyclocitral concentrations in source waters. For a M. aeruginosa cell concentration of 10⁶ cells/L, average release and potential β-cyclocitral concentration were 49 and 44 ng/L. For 10⁷ cells/L, the values increased to 725 ng/L and 545 ng/L, respectively. Environmental conditions, including temperature, pH, and illumination, exhibited substantial impact on cyanobacterial production of β-cyclocitral in aqueous systems.