Screening Of Low Cd/Pb Sweet Corn And Its Combined Remediation Technology For Heavy Metal Contaminated Soils

With the development of China's economy,soil heavy metal pollution is becoming more and more serious.The remediation of heavy metal contaminated soils is difficult and expensive.The heavy metal elements in the soil threaten human health mainly through the food chain.In this study,low-accumulating cultivars of Cd and Pb are selected in accordance with relevant standards,in combination with other phytotechnology and chemical technology,try to improve farmers'enthusiasm for planting and find out the combined technologies which are efficient and non-expensive.In this paper,sweet corn varieties were planted in field experiment,taking into account the heavy metal content and yield factors,the sweet corn varieties with high yield and low Cd and Pb were selected from 8 sweet corn varieties.Then combining with a hyperaccumulating plant,Sedum alfredii,to constitute an intercropping,and also with chemical leaching and lime deep fixing of soil,the decreases of heavy metals in soil were measured,in order to achieve the both targets of the safe agricultural production and the remediation of heavy metal contaminated soils.The main results are summarized as follows:?1?The results of the field experiment showed that there were significant differences in Cd and Pb contents in corn grains and stems and leaves among different sweet corn varieties.Two low-accumulating cultivars SMZHN and JZY meeting food hygiene standards were selected from 8 sweet corn varieties,they could be suitable for the spring-summer seasons in Guangdong Province.?2?Under the field experiment,the low Cd/Pb sweet corn was intercropped with S.alfredii.The content of heavy metals in sweet corn was in accordance with relevant standards.The intercropping corn had higher biomass,and lower the contents of heavy metals Cd and Pb in grains and stems than single cropping.Heavy metal content in soil has dropped.?3?The contents of heavy metals in corn grain and stem and leaf were also in accordance with the relevant standard,grown in treated field with chemical leaching and alkaline amendment,but the yield was lower than first two treatments because of lacking nutrition.?4?Intercropping sweet corn with S.alfredii in a neutral contaminated soil in lysimeters showed that the pH of rainwater affected the growth of the plants,the natural precipitation produced the highest corn yield,while neutralized rainwater resulted in the lowest content of heavy metals in corn grain.?5?In the lysimeter experiment with chemical leaching,the heavy metal contents in corn grain and stem and leaf were low and conformed to relevant standards.The heavy metal content of the four treated sweet corn grains and stems and leaves is also relatively low,in line with relevant standards,MC treatment of soil is more suitable for corn growth and had the highest biomass of sweet corn.The FeCl₃+lime deep fixing treatment had the highest biomass of S.alfredii and the highest concentration of Cd in S.alfredii than the other treatments.The concentration of heavy metals in the four treatments also decreased significantly.