Abstract: Taking the rapidly urbanized Dongguan City of Guangdong as a case, and by using Landsat/TM and ETM⁺ data, the land surface temperature (LST) was retrieved via mono-window algorithm. A standardized method for treating the LST was proposed, and three thermal environment indices (relative thermal effect index, heat contribution index, and cold contribution index) were built to quantitatively study the effects of urban land expansion on urban thermal environment. In 1990-2005, the urban land area in Dongguan had a rapid expansion, and the high temperature zone expanded from island-shape to belt-shape and then to lamina-shape. The relative thermal effect index of urban land decreased after an initial increase, being 0.6 in 1990, 1.0 in 2000, and 0.6 in 2005. The heat contribution index increased persistently, which was 4.5% in 1990, 38.4% in 2000, and 62.9% in 2005, and the cold contribution index increased gradually, which was 1.2% in 1990, 1.8% in 2000, and 6.8% in 2005.

Key words: Eutrophication, Phytoremediation, Sediment, Aquatic plant