Sedum alfredii and Sedum plumbizincicola typically have high heavy metal (such as Zn and Cd) accumulation capacities with fast growth rates and relatively high Pb tolerance in contaminated soils. We compared the accumulation characteristics of heavy metals in Sedum species through meta-analysis. Furthermore, we analyzed the effects of soil organic matter (SOM) and soil pH on Cd, Pb and Zn accumulation by S. alfredii and S. plumbizincicola and the correlation between various metals. Results showed that the accumulations of Cd and Zn in shoots were higher than that of roots, but Pb accumulated in roots more than shoots. Moreover, there is a significant positive correlation between the accumulation of Zn and Cd in shoots. We found that the heavy metal accumulation rate in shoots was higher with lower soil pH. Sedum species had the highest Cd adsorption capacity in 20-30 g/kg SOM and the highest Zn adsorption capacity in SOM less than 20 g/kg. The accumulation rate of Cd in shoots of S. plumbizincicola was increased with exposure time, while the accumulation rate of Zn was slightly decreased.
Keywords: Meta-analysis; cadmium-lead- zinc; contamination; phytoremediation.
S. alfredii and S. plumbizincicola are two common Cd and Zn hyperaccumulators. We systematically compared the accumulation characteristics of heavy metals in Sedum plants and the effects of soil organic matter and pH on the accumulation of Cd, Pb and Zn in S. alfredii and S. plumbizincicola through meta-analysis. This provides certain theoretical knowledge for the application of sedum plants to the phytoremediation of heavy metal contaminated soils.