Effects of chemical additives on the residual amount of heavy metals in soil and asparagus lettuce

Based on current situation of heavy metal contamination of vegetables in Chongqing, potted-plant experiments were conducted to investigate the effects of certain chemical additives, such as limestone, humic acid, and sodium sulfide, on heavy metal uptake of asparagus lettuce and concerning mechanism in soil. Results showed that proper input of limestone and humic 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, and 2.67 g/kg of humic acid sulfide 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 luttce. 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.