Study On The Remediation Of Heavy Metals Contaminated Farmland Soils In Mining Area By Using Calcium-containing Biological Minerals

The development and utilization of mine resources has induced the problem of heavy metal contamination in farmland soil,which causes potential food safety issues and economic loss.This study regards the farmland soil of Shangba Village in Dabaoshan Mining Area of Guangdong as study area and aims to evaluate the effect of applying calcium-containing biological minerals,such as eggshell?ES?,bone-meal?BM?on the immobilization of Cd,Cu,Zn phytoavailability,the growth of plants and the stability of heavy metal fixation through soil incubation and pot experiment.The main findings are as follows:?1?The soil pH value in farmland at S8 area of Dabaoshan mining area is 4.79,and resulted in seriously soil acidification.The average content of Cd,Cu and Zn exceeds the standard value by 2.8,4.5 and 0.8 times,respectively,which means the serious pollution.The results showed that the amendments application could efficaciously raise the pH of acid soil.Meanwhile,the addition of amendments promoted the stability of Cd,Cu,Zn and reduced the heavy metal phytoavailability as compared with control.?2?The effects of applying calcium-containing biological minerals on the enrichment of heavy metals in water spinach and their growth status were investigated by 35d pot experiment.The results showed that compared with the control,the contents of Cd,Cu and Zn in the roots,stems and leaves of spinach on each treatment group decreased significantly as well as the biomass was greatly improved.In all groups,BM1%was the best,the dry biomass of the spinach was 3.4 g/pot,which was 1.08 times higher than control;and Cd content in roots,stems and leaves decreased by 64.20%,67.48%,68.20%,respectively,as compared to control.?3?The effects of applying amendments on the stability of heavy metal immobilization was researched by three-rounds continuous pot experiment?105d total,35d per round?.The results showed that the treatment groups which only were applied by eggshell and bone-meal in the initial stage of the first round,their ratio of heavy metal content in the plant to the bioavailable heavy metal in the soil remained at a low level after the three rounds planting.It indicates that the c calcium-containing biological minerals have good stability.And after three rounds planting,the Cd content in BM₂ has reached with national food safety standards.Applying calcium-containing biological minerals such as eggshell and bone meal as soil amendments can improve the acidic soil which contaminated by heavy metals in an efficient,economical and environmentally friendly manner.And it provided an experimental guidance and theoretical basis for the treatment of heavy metal contaminated farmland and food safety and health in the actual environment.At the same time,eggshells and bone-meal as a by-product of kitchen waste and its processing have also been properly utilized to avoid waste of resources.