Abstract: Emergy theory provides a new theory and method to study the structure and function of ecological-economic systems. In this paper, an emergy analysis was performed on the ecological-economic system of Tianzhu County, Gansu Province, aimed to quantitatively describe the overall characteristics of ecological-economic pattern and its development status of the County, and give comparison with other countries and districts. The main emergy indices calculated were total emergy consumption, emergy/money ratio, emergy self-sufficiency ratio, emergy per capita, and emergy per unit area. In 2008, the total amount of emergy of Tianzhu County was 2.38×10²¹ sej, and the emergy consumption per capita was 1.03×10¹⁵ sej, far lower than those of other countries and districts; while the emergy self-sufficiency rate was 88.87%, and theemergy/money ratio was 3.41×10¹³ sej·$^-1, being higher than those of the cities in coastal developed provinces of China. These results indicated that the economic development of Tianzhu County was based on the over-reliance on and the excess utilization of local resources, and that the ecological-economic system of the county was a closed, inactive, unsustainable system. A series of measures and suggestions were given to promote the sustainable development of Tianzhu County.

Key words: Kandelia candel, Bruguiera gymnorrhiza, Mangrove, Livestock wastewater, Salinity