Risk Assessment of Heavy Metal Pollution in Reclaimed Farmland with Coal Gangue Filling

SHANG Jin; LIU Huihao; LIU Saisai; MA Shoubo; ZHU Shuaimeng; MA Shouchen

doi:10.15933/j.cnki.1004-3268.2023.12.008

Abstract：In order to study the safety of crop production in reclaimed farmland filled with coal gangue,the reclaimed farmland in Chengcun village coal mine area,Huixian City was taken as the research object.The contents of copper(Cu),zinc(Zn),lead(Pb),cadmium(Cd),and chromium(Cr)in the reclaimed soil and crops were measured,and their pollution risks were evaluated.The results indicated that after 3 years of reclamation,heavy metal elements in coal gangue migrated to the overlying soil layer,and the content of heavy metal elements in each soil layer was higher than that of the original covering soil.The distribution characteristics of heavy metal elements in the soil profile were high in the surface and bottom layers,and low in the middle layer.Especially,the content of Cd element in the surface,middle,and deep layers of soil was 62.5%,50.0%,and 100.0% higher than that of the original cover soil,respectively.The ecological risk assessment of reclaimed soil showed that based on the pollution risk screening value of agricultural soil,the ecological risk index of a single element and comprehensive pollution index were both mild risk level.Based on the background values of regional soil elements as the evaluation criteria,the ecological risk index of Cd was a moderate risk level,with ecological risk indices of 44.90,42.55,and 52.35 in the surface,middle,and deep layers of soil,respectively.The single ecological risk index of other heavy metal elements and comprehensive ecological risk indices were all mild risk level.The determination results of heavy metal elements in wheat grains on reclaimed farmland indicated that it was currently safe in production.The average and maximum contents of heavy metal elements did not exceed the grain limit standards,but the minimum values of heavy metal content in grains were higher than those in the surrounding control group farmland.The evaluation of crop pollution risk in reclaimed farmland based on the heavy metal content of wheat grains in the control group showed that the Cd pollution belonged to a moderate risk level,while other heavy metal elements belonged to a mild risk level,and the comprehensive risk index of each element was mild risk level.In summary,there is currently a certain pollution risk in the reclaimed farmland.It is necessary to regularly measure the heavy metal content in the reclaimed soil and crops,and take effective control measures in a timely manner to prevent the heavy metal content in the soil and crops from exceeding the limit standards.