Abstract: To study the diatom community structure and water quality in Small Three Gorges of Jialing River, diatom samples were collected at six sampling sites in dry season (November 2006-March 2007), level season (April-June 2007), and rainy season (July-September 2007). The species composition, cell density, diversity, and evenness index were analyzed, and the water quality was evaluated. A total of 78 species belonging to 2 classes, 10 families and 20 genera were recorded. Cell density was 053×104〖KG-*2〗-〖KG-*7〗358×104 ind·L-1, with a mean value of 155×104 ind·L-1; species diversity index was 162〖KG-*2〗-〖KG-*7〗296, with a mean value of 233; and evenness index was 028〖KG-*2〗-〖KG-*7〗056, with a mean value of 042. On the whole, the water quality of Small Three Gorges belonged to β-mesosaprobic. Shaxi stream and North hot spring had better water quality, belonging to oligosaprobid, followed by Beishi and Niushituo, belonging to β-mesosaprobic, and Yanjing and Maobeituo, belonging to α-mesosaprobic.

Key words: Solid phase microextraction, Liriomyza sativae, Volatile organic compounds, Field trapping trials