Remediation effects of common wetland plants on cadmium- and lead-polluted water environment

Four different concentrations of cadmium (Cd) and lead (Pb) were used to treat six common wetland plants, including Nasturtium officinale R. Br., Raphanus sativus L., Rorippa islandica (Oed.) Borb., Sinapis alba L., Oenanthe javanica (Blume) DC., and Ipomoea aquatica Forsk., under hydroponic culture. Results showed that root length and weight and dry plant weight in N. officinale and R. islandica were significantly lower than that in the control (CK) under both single and combined Cd and Pb stress (P < 0.05). Root length and dry plant weight in R. sativus and S. alba were higher than that in CK under Pb treatment. In the single Cd treatment group, the enrichment coefficients of the six plants were:N. officinale > R. islandica > O. javanica > R. sativus > I. aquatica > S. alba. However, the enrichment coefficient of N. officinale under Pb treatment was the smallest (0.013). The growth conditions of R. sativus seedlings under combined Cd and Pb stress did not differ significantly from that of CK, and showed increased transport coefficients, higher antioxidant enzyme activity, and lower root cell death, indicating that this species has good restorative potential.