Potential of Sonchus arvensis for the phytoremediation of lead-contaminated soil

Sonchus arvensis is one of the pioneer plant species that were found in the abandoned Bo Ngam Pb mine in Thailand. S. arvensis was collected from three sites. The highest Pb shoot concentration was 9317 mg kg-1 and the highest translocation factor (TF) and bioaccumulation factor (BF) values were 2.5 and 6.0, respectively. To investigate Pb uptake capacity of S. arvensis, a hydroponic experiment was performed for 15 d. S. arvensis exposed to 5 mg L-1 Pb solution had the highest Pb shoot accumulation (849 mg kg-1). In a pot study, S. arvensis was grown in Pb mine soils amended with organic and inorganic fertilizers for 2 mo. The addition of organic fertilizer to the soil increased plant dry biomass sharply. All treatments with ethylene-diamine-tetra-acetic acid (EDTA) had Pb accumulation in shoots greater than 1000 mg kg-1 and the highest Pb shoot accumulation was found in S. arvensis grown in soil amended with organic fertilizer and EDTA (1397 mg kg-1). In a field trial study, S. arvensis was grown at three sites in the mine area for 6 mo. S. arvensis could tolerate a total Pb of 100,000 mg kg-1 in the soil and accumulated Pb in the shoots up to 3664 mg kg-1 with high TF (2.19) and BF (2.38) values. These results suggest that S. arvensis is a good candidate for Pb phytoremediation.