Based on current situation of heavy metal contamination of vegetables in Chongqing

pot experiments were conducted to investigate the effects of certain chemical additives

such as limestone

humic acid

sodium sulfide and sodium selenite

on heavy metal uptake of asparagus lettuce and concerning mechanism in soil. Results showed that proper input of limestone and humie acid could significantly reduce mercury concentration in asparagus lettuce

whereas sodium sulfide could reduce lead uptaken by asparagus lettuce. According to the safety of agricultural products

the best chemical additives and their dosages which could reduce mercury

cadmium

and lead were obtained. Application of 10.0 g/kg of limestone

2. 67 g/kg of humic acid sulfide and 2.19 mg/kg sodium selenite had the most effective results on reduction of mercury in asparagus lettuce

and input of 10.0 g/kg of limestone could most effectively decrease the cadmium concentration in asparagus lettuce. Meanwhile

10. 0 g/kg of limestone

2.67 g/kg of humic acid

and 0. 47 mg/kg of sodium sulfide could best reduce lead concentration in asparagus lettuce.