Odor contribution evaluation of six species of microalgae and corresponding odorants to whole fishy odor in drinking water source

Disgusting fishy odor could break out inside oligotrophic drinking waterbody in winter with low temperature. In preceding study, six species of fishy odor-producing microalgae and totally twenty fishy odorants were identified in drinking water source of Tongyu River, however, contributions of odorants and microalgae to whole fishy odor were unclear. In this study, odor contribution of microalgae and corresponding odorant to whole fishy odor was evaluated comprehensively. The results indicated that 2,4-decadienal, 2,6-nonadienal and 2,4-heptadienal were key fishy odorants based on OAV evaluation. Even though OAV of some odorants were below one, 80.6-90.79% of fishy intensities were explained for source water by reconstitution test. Approximately, 83.93%, 88.89%, 82.69%, 90.38%, 83.02%, 88.46% of fishy intensities were explained for <i>Dinobryon sp., Cryptomonas ovate, Cyclotella, Ochromonas sp., Synedra</i>, <i>Melosira</i> based on reconstituted samples, suggested that there existed synergistic effect for fishy odor among odorants. By assessing gross production of odorants, gross OAV of odorants, odorant production for single cell, gross odorant ratio and gross OAV ratio, contribution rank of isolated microalgae to whole fishy odor from maximum to minimum should be <i>Ochromonas sp.,</i> which accounted for 21.2% of gross odorant's OAV, <i>Melosira</i> (accounted for 19.68%), <i>Cryptomonas ovate</i> (accounted for 19.63%), <i>Dinobryon sp.</i> (accounted for 18.27%), <i>Synedra</i> (accounted for 14.54%), <i>Cyclotella</i> (accounted for 6.68%). Contributions of multiple odorants and microalgae to fishy odor were first studied, which will provide more scientific basis for managing fishy odor in drinking water.