Abstract: In a constructed wetland system, appropriate choice of plant species is a key factor affecting metal removal from metal-contaminated soils, sediments and wastewaters. A hydroponic experiment was conducted to compare lead (Pb) tolerance indices and uptake among 18 emergentrooted wetland plants under 0, 10 and 20 mg·L^-1 Pb exposures. The results indicated that Pb translocation from root to shoot was generally low in all species tested. There were significant differences among the 18 wetland plants in their Pb tolerance indices and also Pb uptake under the same Pb treatment. Some wetland plants with higher Pb tolerance indices and Pb concentrations in shoot suggested that the detoxification system in plant may play an important role in alleviating Pb toxicity. Under the 20 mg·L^-1 Pb exposure, Veronica serpyllifolia had the highest accumulation of Pb in shoots (8226 mg Pb·kg^-1), while Fimbristylis monostachya had the lowest accumulation of Pb in shoots (50 mg Pb·kg^-1). In addition, Alternanthera philoxeroides having higher accumulation of Pb in shoots still did not show any severe symptoms of Pb toxicity. The data obtained should help in future species selection in designing wetlands in Pbcontaminated environments.

Key words: rice, rice quality, Yellow River Delta, organic agriculture, pesticide residue., rice-duck mutualism