Occurrence of odour-causing compounds in different source waters of China

In this study, occurrence of the main odorous compounds in different types of source water in China, including rivers, lakes and reservoirs, were investigated by integrating the methods of flavour profile analysis (FPA) and sensory-GC/MS analysis. Simultaneous distillation extraction (SDE) was chosen as the preconcentration technique while the odour-causing compounds were identified with sensory-GC/MS. It was found that MIB, which is mainly produced by some cyanobacteria and actinomycetes, was one of the most widely distributed odour-causing compounds, regardless of source type. A peak MIB concentration of approximately 170 ng l⁻¹ was recorded in MY Reservoir in October 2005. Among the nine investigated sites, YH Reservoir in Hebei Province was the only site showing geosmin production. A peak geosmin concentration exceeding 7,000 ng l⁻¹ was detected in July 2007. In June 2007, a serious taste/odour (T/O) event occurred in Wuxi City, and the offensive flavour was a strong septic or marshy odour caused by dimethyl trisulfide (431 ng l⁻¹ in finished water). Septic/swampy and earthy/musty odours occurred in source waters of Shanghai and Guangzhou. It was found that dimethyl trisulfide was mainly responsible for the septic/swampy odour and MIB for the earthy/musty one. Dimethyl trisulfide might be an important T/O-causing compound in China.