Variations in several morphological characteristics and Cd/Pb accumulation capacities among different ecotypes of torpedograss responding to Cd-Pb stresses.

Torpedograss (Panicum repens) has been recognized as an useful plant species for phytoremediation of water-level-fluctuation zones, which is a worldwide challenge. In this study, 10 ecotypes collected from tropical zone and flooded habitats (Group A) and subtropical zone and drought habitats (Group B) were used to clarify their responses to Cd-Pb stresses and effects of long-term adaptation on their morphological features and Cd-Pb accumulation capacities. Branch capacity, shoot and root biomasses of Group A under control were smaller than those of Group B, while the opposite results were observed under Cd-Pb stresses. The average plant shoot Cd concentrations of Group A under L-Cd-Pb and H-Cd-Pb were 24.84 and 52.38 mg kg-1, respectively, significantly lower than those of Group B (36.81 and 67.60 mg kg-1), while the variation among each group was insignificant, suggesting that habitat isolation and long-term adaptation may have led to differentiation in morphological features and metal uptake capacity. Torpedograss possesses high tolerance to Cd-Pb toxicities, and those ecotypes with larger biomass had higher Cd-Pb accumulation capacities. Torpedograss is a potential plant species for Cd phytoremediation and approximately 16 years would be required to clean soil contained by Cd as high as 10 mg kg-1 using the selected torpedograss ecotypes.

Fabrication of Chitin microspheres supported sulfidated nano zerovalent iron and their performance in Cr (VI) removal.

Sulfidated nanoscale zerovalent iron (S-nZVI) has been extensively studied for the reductive removal of Cr(VI), but its applicability is limited by agglomeration and unexpected efficiency reduction. In this study, chitin microsphere supported sulfidated nanoscale zero-valent iron (S-nZVI@Chi-M) was prepared by in-situ one-step reduction method and used to remove Cr(VI) from water. Compared to chitin and chitosan powder, Chi-M with nanofibrous structure and large surface area performed best in stabilizing S-nZVI with a Fe0 loading content of 3.01 wt%. The S-nZVI particles were homogeneously distributed on the surface of Chi-M, effectively avoiding agglomeration. Compared with bare nanoparticles and supported nZVI, S-nZVI@Chi-M showed significantly enhanced Cr(VI) removal capacity (924.5 mg Cr(VI) for per gram of effective Fe0). The influences of sulfidation degree, dosages, initial Cr(VI) concentration, pH, DO, humic acid and typical ions on Cr(VI) removal kinetics were further studied. S-nZVI@Chi-M could be recycled for at least 4 times with acceptable reactivity. The mechanism investigation results indicated that the Cr(VI) removal was a complex process of reduction, adsorption and co-precipitation under the synergistic effect of Chi-M and S-nZVI. This work provides new ideas for the continuous fabrication of highly reactive nanoparticles, hopefully expanding the application scope of biomass resources in pollution remediation.

Accumulation of Pb, Cu, and Zn in native plants growing on contaminated sites and their potential accumulation capacity in Heqing, Yunnan.

Phytoremediation is one of the cost-effective and environmental friendly technologies used to remove contaminants from contaminated soils, which has been intensively studied during the last decade. Presently, few economical and effective remediation methods are available for the remediation of Pb contaminated sites. This study was conducted to assess the potential of 19 plants growing on contaminated sites in Pb mine area. Plants and associated soil samples were collected and analyzed for total metal concentrations. While total soil Pb, Cu and Zn concentrations varied from 1,239 to 4,311, 36 to 1,020 and 240 to 2,380 mg/kg, those in the plant shoots ranged from 6.3 to 2,029, 20 to 570, and 36 to 690 mg/kg, respectively. Among the plants, we found that one cultivated crop (Ricinus communis L.) and two native species (Tephrosia candida and Debregeasia orientalis) have a great potential for phytoremediation of Pb contaminated soils, the Pb hyperaccumulation capacity of the 3 plants was found as the order: R. communis > D. orientalis > T. candida in the investigated area.

[The expression, purification and activity analysis of the rice chitinase gene in Escherichia coli].

The cloned cDNA sequence of rice (Oryza sativa L. Cpslo17) chitinase gene Oschi was cloned, (which was registered in GenBank, the accession number: EU045451) ligated with the expression vector pGEX-4T-1, and transformed into E. coli BL21(DE3). The expression of Oschi was induced by IPTG, and the conditions were optimized. After purification the in vitro activity of Oschi chitinase was analyzed, and the results indicated that it could efficiently degrade chitin.