Abstract: A pot experiment was conducted to assess the phytoextraction potential for lead (Pb) of Cosmos sulphureus and Cosmos bipinnatus under different treatments of N, NP and NPK fertilizer applications in Pb contaminated soils collected from northern China. The results showed that fertilization significantly increased the biomass, shoot Pb concentrations and accumulation in both C. sulphureus and C. bipinnatus. Especially, NPK fertilization had strongest effects on Pb accumulation. Lead concentrations in the shoots ofC. sulphureus and C. bipinnatus under NPK treatment were 1.59-1.89 and 1.17-1.32 times as high as that under other treatments. The enrichment amounts of Pb in the shoots were 1.15-3.21 and 1.18-4.28 times as high as that under the control treatment, respectively. Fertilization treatment significantly improved the transport ability of Pb of both species. The bioconcentration factors (BCF) increased from 0.17 in the control to 0.22 in the NPK treatment for C. sulphureus, and from 0.29 in the control to 0.36 in the NPK treatment for C. bipinnatus. The metalenriched particles (MRG) were the major enriched position in the subcellular fractions of both species (more than 70%). In conclusion, C. sulphureus and C. bipinnatuscan be used as plant materials for remediation of Pbcontaminated soil. Moreover, NPK fertilizers can effectively improve remediation efficiency, and C. sulphureusperforms better than C. bipinnatus.

Key words: heterogeneous distribution of soil resource, nutrient patch., warming, fine root