Identification and Distribution Characteristics of Odorous Compounds in Sediments of a Shallow Water Reservoir

Odorous sediments containing volatile organic sulfur compounds (VOSCs) are a common issue in shallow water reservoirs globally. Volatile organic sulfur compounds are a typical class of malodorous substances that have attracted widespread attention due to their pungent odors and extremely low odor thresholds. The insufficient hydrodynamic conditions in the reservoir area lead to the accumulation of pollutants in the sediment, where biochemical reactions occur at the sediment-water interface, serving as a significant source of foul-smelling substances in the water body. This study analyzed sediment samples from 10 locations across a shallow water reservoir using flavor profile analysis, an electronic nose, and gas chromatography-mass spectrometry. The predominant odor types were earthy/musty and putrid/septic, with key odorants being VOSCs, 2-methylisoborneol, and geosmin. The results revealed VOSCs from organic matter account for up to 96.7% of odor activity. More importantly, concentrations and release fluxes of VOSCs consistently decrease along the water flow direction from dam regions to tail regions. This trend matches organic matter accumulation patterns in shallow reservoirs and highlights dam areas as hotspots for malodorous sediment. The generalized spatial distribution pattern and identification of key malodorous compounds establish a basis for understanding and managing odor issues in shallow freshwater reservoir sediments.