[Species, Habitat Characteristics, and Screening Suggestions of Cadmium Hyperaccumulators in China]

Phytoremediation, as a green and effective in-situ remediation technology for heavy metal-contaminated soil, has attracted the attention of Chinese scholars and has resulted in a series of achievements over the past 20 years. In this study, the species characteristics, distribution of field discovery sites in various vegetation zones, habitat characteristics, habitat geological characteristics, and geochemistry of cadmium (Cd) of the Cd hyperaccumulators in China reported in the relevant literature from the past 20 years (from 2002 to 2021) were summarized by searching for related keywords. Finally, suggestions were proposed for the screening of new Cd hyperaccumulators. The results showed that a total of 45 species of Cd hyperaccumulators in China have been reported so far. In terms of plant species, they belonged to 22 families and 36 genera, among which Compositae with 14 species was the most abundant. There were 25 species discovered through the field investigation, which were mainly distributed in the subtropical broadleaf evergreen forest region of southern China. Additionally, the Cd hyperaccumulators discovered by field surveys were mainly found in high Cd-concentrated soils surrounding lead-zinc mines. In conclusion, abundant plant resources, high concentrations of heavy metal soils, and long-term domestication jointly promoted the formation of hyperaccumulators. Therefore, the region with these three points could be considered a high probability region for the presence of hyperaccumulators, and the screening of hyperaccumulators could be carried out around this. We proposed that the screening of new hyperaccumulators can be carried out through the following six steps:the identification and investigation of high probability areas, the enrichment capability test, the enrichment capability test in low concentration levels, the enrichment capability test between different ecotypes, the succession of enrichment capability, and the test of remediation proficiency.