[Remediation Potential of Pueraria thomsonii Benth. on Farmland Soil Contaminated by Cd, As, and Pb].

Abstract

This study investigated the growth, enrichment characteristics, and remediation potential of Pueraria thomsonii Benth. （"Hua ye ge" and "Gan ge er hao"） on cadmium （Cd）, arsenic （As）, and lead （Pb）-contaminated soils, the remediation potential of P. thomsonii in a large field experiment under different trial fields. The results showed that the whole plant biomass （dry weight） of P. thomsonii was 4.58-12.45 t·hm^-2, and the biomass of "Hua ye ge" was higher than that of "Gan ge er hao." The contents of Cd, As, and Pb in different parts of P. thomsonii were 1.63-17.04, 0.15-20.97, and 0.40-231.12 mg·kg^-1, respectively. The accumulations of Cd, As, and Pb of P. thomsonii were 14.01-109.06, 4.10-27.59, and 49.97-305.69 g·hm^-2, respectively. The removal rates of Cd, As, and Pb of P. thomsonii were 0.40%-2.57%, 0.02%-0.08%, and 0.06%-0.09%, respectively. The bioconcentration factors of P. thomsonii for Cd, As, and Pb were 0.09-13.12, 0.01-0.38, and 0.01-0.76, respectively, and the translocation factors were 0.50-4.72, 1.27-15.89, and 1.19-35.68, respectively. Among them, the contents of Cd, As, and Pb in the main vine and the As accumulation and removal rate of "Hua ye ge" were all significantly higher than that of "Gan ge er hao" （P < 0.05）. The biomass was mainly concentrated in the tuber, while the heavy metal content and accumulation was mainly concentrated in the stem and leaf. Correlation analysis showed a significant positive correlation between soil Cd content and Cd content in the main vine and leaf of P. thomsonii （P < 0.05）. A significant positive correlation was observed between soil Pb content and Pb content in all parts of P. thomsonii （P<0.05）. Except for "Hua ye ge" in Xiangdong, the content of heavy metals in the commercial P. thomsonii portion （arrowroot） was lower than the standard limit for medicinal plants. In summary, the P. thomsonii showed strong absorption and transport capacity for Cd, As, and Pb. "Hua ye ge" was selected as a potential enrichment plant source for the remediation of severe Cd-based combined contaminated soil. Additionally, "Gan ge er hao" （used as Pueraria powder） was selected as a potential enrichment plant for the remediation of mild and moderate Cd-contaminated soil.