Relationship between soil Pb pollution and Pb contents in vegetables and pollution threshold of soil Pb

In order to determine the impact of soil heavy metal pollution on vegetable and to enhance quality of green vegetable production, the relationship between soil Pb content and Pb pollution of vegetables was studied under greenhouse conditions using five commonly cultivated foliage vegetables (Lactuca sativa var. Asparagina, Schizonepeta tenuifolia Briq, Lpomoea aquelica, Lactuca sativa, Amaranthus hypochondriacus) in Zhengzhou, Henan Province. Soil Pb pollution threshold for the production of green vegetables was analyzed as well. The results show that low Pb polluted soils have insignificant effect on vegetable growth and output. Pb content in the 5 vegetables increases with increasing density of soil Pb, and no consistent pattern of relationship exists between Pb content in the soil and vegetables. Simulated Pb threshold limit is: L. sativa var. Asparagina 39.909 2 ±2.446 9 mg·kg^-1, S. tenuifolia 43.898 6±3.585 5 mg·kg^-1, L. aquelica 35.293 4±1.787 2 mg·kg-1,L. sativa 33.696 4±2.151 2 mg·kg^-1,A. hypochondriacus 34.539 6±2.425 4 mg·kg^-1. Pb concentration (ranked from highest to lowest) is as follows: L. sativa＞A. hypochondriacus＞L. aquelica＞L. sativa var. Asparagina＞S. tenuifolia.