Effects of the accumulation of the rare earth elements on soil macrofauna community

The accumulation of rare earth elements (REEs) in soil has occurred due to the pollution caused by the exploitation of rare earth resources and the wide rare earth fertilizers in agriculture. The accumulation of REEs has a toxic effect on the soil macrofauna community. 12 study samples were collected near a mine tailings dam with a large amount of REEs by distance gradient sample method. The total concentration of REEs was analyzed and the results were compared with that of the sample from a control site. The effects of the amount of REEs in the soil on the soil macrofauna community were also analyzed. The results showed that the accumulation of REEs in soil was significant in the study area and its concentration was strongly correlated with the distance from the pollution source. One-way ANOVA analysis indicated the significant differences in soil macrofauna communities among the different sites. The ordination obtained through the redundancy analysis demonstrated that the concentration of REEs and the total nitrogen, total potassium and pH, had affected the soil macrofauna community. A small amount of REEs in the soil can promote the diversity of soil macrofauna, but a large amount of REEs can reduce its diversity. The insect groups of Carabidae and Dermaptera were comparatively sensitive to the concentration of REEs in soil, and could be used as an indicator of soil pollution of REEs. However, the Formicidae and Stibaropus formosanus exhibited a high tolerance to REEs in soil. We believe that it is very important for the soil environment protection to strictly control the application of the rare earth fertilizers in agriculture in China.