Natural and Human Factors Affect the Distribution of Soil Heavy Metal Pollution: a Review

Summarized the heavy metal pollution caused by natural and human activities. The natural causes include the migration and redistribution of soil debris and the hydraulic migration of soil parent rock with high background value under the action of wind; human factors include mining, abandoned mining areas, fertilizer and pesticide application, and sewage irrigation. By examining the sources of heavy metals in soil, the temporal and spatial variation and source variation of heavy metal pollution can be summarized, and then find a reasonable way to intervene as early as possible from the origin to reduce the harm of this pollution to the soil. Finally, future research trends and key problems were indicated, which laid a theoretical foundation for further effective research. Graphical abstract