Temporal and spatial pattern, sources, and main controlling factors of odor compounds in Qiandaohu Reservoir.

The ubiquitous presence of algal-derived odors in large lakes and reservoirs constitutes a critical environmental concern. Particularly during the high-temperature summer months, localized regions of Qiandaohu Reservoir have exhibited markedly elevated concentrations of odor compounds. To investigate the intricate relationships among odor compounds, algae communities, and environmental factors in Qiandaohu Reservoir, and to forestall the impact of odor compounds on the quality of drinking water, this research implemented a systematic monthly survey to monitor several types of odor compounds, algal communities, physicochemical factors, and associated synthetases. The result demonstrated that the odor issue in Qiandaohu Reservoir is not yet severe. Among the detected compounds, dimethyl sulfide, dimethyldisulfide, and β-cyclocitral were all below the odor threshold, while dimethyl trisulfide, 2-methylisoborneol, geosmin, and β-ionone exceeded the odor threshold in some samples. The odor compounds are jointly influenced by abiotic environmental conditions and algae, presenting conspicuous horizontal, vertical, and seasonal distribution disparities. Notably, total nitrogen, total phosphorus, and the TN/TP ratio exert a substantial influence. Algae play a pivotal role in contributing to these odor compounds, warranting particular attention to the composition and dynamic alterations of the algal community during the summer and autumn seasons. This research comprehensively investigates the spatiotemporal patterns, sources, and controlling factors of odor compounds in a large drinking water source reservoir with relatively lower trophic status, providing new insights into odor management in such ecosystems.