Effects of vegetation restoration on accumulation and translocation of heavy metals in post-mining areas

Vegetation restoration has been recognized as an effective ecological measure to mitigate soil heavy metal contamination in open-pit mining areas. However, little is known about the processes of accumulation and translocation of heavy metals in naturally restored soil-plant systems in these areas. In this study, soil and plant samples were collected from three natural restoration sites of different post-mining ages (2, 7, and 15 years) to investigate the concentration, accumulation, and translocation of heavy metals in plant tissues (roots, stems, and leaves) of two different plant life forms (trees and shrubs). The results showed that heavy metals occurred at different concentrations in different tissues; and that site age significantly affected the concentration of metals, with higher concentration in older sites. Similarly, the accumulation of metals from soil to roots and the translocation from roots to stems were greater in older sites. We combined redundancy analysis, correlation analysis and multiple regression analysis to determine the effect of environmental factors on accumulation and translocation. Results showed that plant life form took the largest weight for accumulation of Pb, Ni, Cd, and Cr, and for translocation of Ni, Cu, and Zn. Site age made the highest contribution to accumulation of As, and to translocation of Hg and Cd. The accumulation of Hg and translocation of Pb, As, and Cr were most affected by total phosphorus. Soil pH was the major contributor to accumulation of Cu and Zn. These findings could provide some reference for post-mining soil remediation, particularly for gold mines.

Automated summary

Vegetation restoration is recognized as an effective measure to mitigate soil heavy metal contamination in open-pit mining areas, but the processes of accumulation and translocation of heavy metals in naturally restored soil-plant systems are not well understood. This study investigated the concentration, accumulation, and translocation of heavy metals in different plant tissues and life forms at three natural restoration sites with different post-mining ages. The findings suggest that heavy metal concentrations vary among tissues, with higher concentrations in older sites, and that plant life form and site age play significant roles in the accumulation and translocation of heavy metals.