Impact of urbanization on farmland environmental quality in Baoshan District, Shanghai

The environmental risk index (I_ER) method was utilized to evaluate heavy metal (Cd, Cr, Cu, Pb, and Zn) environmental risk in farmland soil of Baoshan District, Shanghai. An integrated evaluation indicator system for urbanization was founded combining 4 major factors, such as population, economy, social life, and ecological environment, and used to measure urbanization of the district in 2003 and 2007 for exploration of quantitative relationship between urbanization and farmland soil environmental risk. Results show that compared with the soil in 2003, the farmland soil in Baoshan in 2007 was obviously higher in heavy metal (Cr, Cu, Pb and Zn) concentration, which intensified the farmland soil heavy metal environmental risk. Spatially, the environmental risk expanded from southeast towards northwest. Its urbanization level increased significantly and an obvious positive correlation existed between the urbanization and the environmental risk index. The current urbanization development mode in Baoshan seems unfit to protection of its agricultural environmental quality.