The objective of this experiment was to evaluate the effects of Triton X-100 (1000 mg kg⁻¹) and nano-SiO₂ (500 mg kg⁻¹) on Erigeron annuus (L.) Pers. grown in phenanthrene spiked soil (150 mg kg⁻¹) for 60 days. Results show that untreated groups, groups treated with both Triton X-100 and nano-SiO₂, exhibited better phenanthrene degradation rates and improved root biomasses, chlorophyll contents, and soil enzyme activities. This study demonstrates that Triton X-100 combined with nano-SiO₂ protects plants, alleviating the stress of polycyclic aromatic hydrocarbons (PAHs), and can provide a means for improving phytoremediation of PAH contaminated soils.

Identification and classification of metal-accumulating plant species is essential for phytoextraction. Cluster analysis is used for classifying individuals based on measured characteristics. In this study, classification of plant species for metal accumulation was conducted using cluster analysis based on a practical survey. Forty plant samples belonging to 21 species were collected from an ancient silver-mining site. Five groups such as hyperaccumulator, potential hyperaccumulator, accumulator, potential accumulator, and normal accumulating plant were graded. For Cd accumulation, the ancient silver-mining ecotype of Sedum alfredii was treated as a Cd hyperaccumulator, and the others were normal Cd-accumulating plants. For Zn accumulation, S. alfredii was considered as a potential Zn hyperaccumulator, Conyza canadensis and Artemisia lavandulaefolia were Zn accumulators, and the others were normal Zn-accumulating plants. For Pb accumulation, S. alfredii and Elatostema lineolatum were potential Pb hyperaccumulators, Rubus hunanensis, Ajuga decumbens, and Erigeron annuus were Pb accumulators, C. canadensis and A. lavandulaefolia were potential Pb accumulators, and the others were normal Pb-accumulating plants. Plant species with the potential for phytoextraction were identified such as S. alfredii for Cd and Zn, C. canadensis and A. lavandulaefolia for Zn and Pb, and E. lineolatum, R. hunanensis, A. decumbens, and E. annuus for Pb. Cluster analysis is effective in the classification of plant species for metal accumulation and identification of potential species for phytoextraction.