MIB-producing cyanobacteria (Planktothrix sp.) in a drinking water reservoir: Distribution and odor producing potential

The production of odorant 2-methylisoborneol (MIB) in water bodies by Planktothrix sp. have not been understood very well. Through a four-year investigation in Miyun Reservoir, a huge mesotrophic drinking water reservoir known to have the MIS episodes, we found that the Planktothrix sp. bloomed during September and October causing the high levels of MIS in the reservoir. The concentration of MIS and the biomass of MIB-producing cyanobacteria Planktothrix were measured (n = 887) at different sites and depths during different seasons. The results indicated that the shallow region of the reservoir is the major habitat for Planktothrix sp. due to that the light is able to penetrate down to the relatively high concentrations of nutrients close to the sediments. Quantile regression analysis between Planktothrix biomass and MIS concentration shows that the risk of MIS exceeding the odor threshold (15 ng L-1) in water was as high as 90% when the Planktothrix density was more than 4.0 x 10(5) cells L-1, while the risk was reduced to 10% when the Planktothrix density remained below 1.6 x 10(4) cells L-1. This study will improve the understanding of the environmental behaviors of Planktothrix sp., and can provide useful information for better management of drinking water lakes/reservoirs experiencing the taste and odor (T&O) problems caused by deep living cyanobacterial species. (C) 2014 Elsevier Ltd. All rights reserved.