Through the investigation of typical soils of protected vegetable cultivation in Shouguang of Shandong Province, Shangqiu of Henan Province, Siping of Jilin Province, Wuwei of Gansu Province in the North China, the characteristics of heavy metal accumulation and their distributions in the soil profiles and the mobility of heavy metals were studied systematically via laboratory analysis and field experiments. The balance of heavy metals between inputs and outputs in the soils of the protected vegetable culti...