『保健医療科学』 2022 第71巻 第2号 p.184-185（2022年5月）
Behavior of musty odor compounds caused by cyanobacteria in drinking-water-supply watershed
Objectives: To clarify the general relationships between meteorological factors and musty odor production, nationwide musty odor occurrence cases in drinking water sources reported in literatures, and long term monitoring data at Takataki dam reservoir are investigated.
Methods: Average temperature, precipitation, and sunshine duration in the week before the detection date of the maximum concentration of geosmin or 2-MIB, which are musty odor causing compounds, in each case were calculated.
Results: About the temperature in the nationwide cases, all the geosmin cases caused by Anabaena spp. were higher than 17°C , most of the 2-MIB cases caused by Oscillatoria spp. were under the range of 20- 28°C , and most of the 2-MIB cases caused by Phormidium spp. were under the range of 11-20°C . In the high-concentration cases observed in Takataki Dam reservoir, all the geosmin cases caused by Anabaena spp. were higher than 16°C . And 2-MIB cases were under the range of 8-28°C , however, it was suggest- ed that the cases at higher than 20 °C were caused by Oscillatoria spp., and the cases at lower than 10 °C were caused by Phormidium spp.. In addition, it was considered that low precipitation, which prolongs the hydraulic retention time, was one of the important conditions, however the sunshine duration was not sufficient as an index for predicting the musty odor occurrence.
Conclusion: It was concluded that the temperature at which each cyanobacteria genus can grow, and the low precipitation were important conditions of the musty odor occurrence. This study might be useful for drinking water source monitoring.
keywords: drinking water supply, musty odor, cyanobacteria, temperature, precipitation, sunshine duration