Phytoextraction of heavy metals by eight plant species in the field

Phytoremediation is an in situ, cost-effective potential strategy for cleanup of sites contaminated with trace metals. Selection of plant materials is an important factor for successful field phytoremediation. A field experiment was carried out to evaluate the phytoextraction abilities of six high biomass plants ( Vertiveria zizanioides, Dianthus chinensis, Rumex K-1 ( Rumex upatientia x R. timschmicus), Rumex crispus, and two populations of Rumex acetosa) in comparison to metal hyperaccumulators ( Viola baoshanensis, Sedum alfredii). The paddy fields used in the experiment were contaminated with Pb, Zn, and Cd. Our results indicated that V. baoshanensis accumulated 28 mg kg(-1) Cd and S. alfredii accumulated 6,279 mg kg(-1) Zn ( dry weight) in shoots, with bioconcentration factors up to 4.8 and 6.3, respectively. The resulting total extractions of V. baoshanensis and S. alfredii were 0.17 kg ha(-1) for Cd and 32.7 kg ha(-1) for Zn, respectively, with one harvest without any treatment. The phytoextraction rates of V. baoshanensis and S. alfredii for Cd and Zn were 0.88 and 1.15%, respectively. Among the high biomass plants, R. crispus extracted Zn and Cd of 26.8 and 0.16 kg ha(-1) , respectively, with one harvest without any treatment, so it could be a candidate species for phytoextraction of Cd and Zn from soil. No plants were proved to have the ability to phytoextract Pb with high efficiency.