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

Abstract

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. K E Y W O R D S heavy metals, plant life form, plant tissues, post-mining sites, site age 1 | INTRODUCTION Mining activities have been recognized as the major driver associated with soil degradation (Acosta et al., 2011; Food and Agriculture Organization, 2015). In particular, heavy metal contamination of soils (e.g., Pb, Hg, Cd), which is harmful to environmental and human health, has been identified as one of the primary threats posed by mining activities (Li, Ma, Kuijp, Yuan, & Huang, 2014). It is estimated that the area of land contaminated by heavy metals resulting from mining activities has reached 1.5 million ha in China, and this area is increasing at a rate of 46,700 ha yr −1 (Zhuang, McBride, Xia, Li, & Li, 2009). Mining for gold is particularly bad for heavy metal contamination (such as Pb, Hg, As, Ni, Cd, Cr, Cu, and Zn), where over 99% of waste materials contain at least

Soil bacterial community responses to cadmium and lead stabilization during ecological restoration of an abandoned mine

“…G + T was more effective in reducing soil‐available Cd content, by up to 60.38% compared with that in the control. Studies have shown that trees have a stronger ability to stabilize Cd than shrubs (Xu et al, 2021). Generally, roots are the main plant parts to accumulate heavy metals from the soil (Bech et al, 2016).…”

“…They showed that mixed plantings of Ulmus pumila and Amorpha fruticosa Linn (trees and shrubs, respectively) performed better in reducing Cd concentration than a stand of pure trees. Therefore, mixed trees and shrubs demonstrated better immobilization of heavy metals than pure trees (Xu et al, 2021).…”

“…Moreover, soil contamination by heavy metals, such as cadmium (Cd) and lead (Pb), in abandoned mining sites is a severe environmental issue because it can lead to groundwater contamination and pollution of surrounding soils (Fields, 2003). Thus, contamination by heavy metals in abandoned mining areas has become an urgent issue in environmental remediation (Xu et al, 2021).…”

Potential and Mechanisms for Stable C Storage in the Post-Mining Soils under Long-Term Study in Mitigation of Climate Change

“…Previously conducted studies suggested that the application of organic matter improves the content of available P in the soil, which is a result of supported microbial activity [32]. A similar study also showed an increase in total P along with the remediation of post-mining areas [33].…”

“…They proposed that soil amendment under post-mining remediation effect in the increase of N availability. Another study indicated a TN increase along with remediation age [33].…”