Phytoremediation effect of Scirpus triqueter inoculated plant-growth-promoting bacteria (PGPB) on different fractions of pyrene and Ni in co-contaminated soils.

At present, few reveal the mechanism of inoculation plants with PGPB to remediate PAH-metal co-contaminated soil by analyzing the chemical speciations of contaminants. This study investigated the influence of inoculation plants with PGPB on different fractions of pyrene and Ni in rhizospheric and non-rhizospheric soil. The results demonstrated that the addition of PGPB brought the extensive increase of FDA activities in pyrene-Ni co-contaminated soil. PGPB increased the resistance of plants in nickel and pyrene-Ni contaminated soil, but decreased the plant biomass in single pyrene contaminated soil. The addition of PGPB efficiently decreased bioaccessible fractions of pyrene and increased the bioavailability of Ni in both rhizospheric and non-rhizospheric soil. Although inoculation plants with PGPB significantly increased the accumulation of Ni in single Ni and pyrene-Ni co-contaminated soil, the poor bioavailability of Ni in rhizospheric soil still restricted the phytoremediation of the heavy metal. The presence of pyrene hindered the inoculated plant from accumulating Ni to some extent. On the contrary, the presence of Ni significantly promoted the degradation of pyrene in both rhizospheric and non-rhizospheric soil after inoculation plants with PGPB.

Chen X ，Liu X ，Zhang X ，Cao L ，Hu X ... -  《-》

Effect of Bacillus subtilis and NTA-APG on pyrene dissipation in phytoremediation of nickel co-contaminated wetlands by Scirpus triqueter.

A complex mix of organic pollutants and heavy metal made the remediation of contaminated wetlands more difficult. Few research focus on the remediation for pyrene enhanced by chemical reagents and pyrene degrading bacteria in the nickel co-contaminated soil. In this paper, the effect of chemical reagents (nitrilotriacetic acid and alkyl polyglucoside) and Bacillus subtilis on pyrene dissipation in phytoremediation of nickel co-contaminated soil by Scirpus triqueter was investigated. Similar seedlings of Scirpus triqueter were moved to uncontaminated soil and pyrene-nickel co-contaminated soil. The pots (14.8 cm diameter and 8.8 cm height) were set up in greenhouse and treated in different ways. After 60 days, plant biomass, radial oxygen loss (ROL), soil dehydrogenase activity (DHA) and pyrene concentration in soil were determined. Results showed that ROL rate and DHA in different groups was positively correlated with pyrene dissipation from soil. In the process of remediation, chemical reagents might have an indirect slight effect on pyrene dissipation (pyrene dissipation increased 21%) by affecting DHA firstly and redistributing pyrene fractions in the presence of pyrene degrading bacteria. Pyrene degrading bacteria were likely to affect pyrene dissipation by impacting ROL rate and DHA and played a more vital role in contributing to pyrene dissipation (pyrene dissipation increased 45%) from wetland. This study demonstrated that phytoremediation for pyrene in nickel co-contaminated soil by Scirpus triqueter can be enhanced by the application of NTA-APG and pyrene degrading bacteria and they could be reasonably restore the ecological environment of PAH-contaminated wetlands.

Liu X ，Hu X ，Zhang X ，Chen X ，Chen J ，Yuan X ... -  《-》

Effect of plant-growth-promoting rhizobacteria on phytoremediation efficiency of Scirpus triqueter in pyrene-Ni co-contaminated soils.

The aim of this study was to investigate whether the plant-growth-promoting rhizobacteria (PGPR) could enhance phytoremediation efficiency of Scirpus triqueter (S.triqueter) in the pyrene-Ni co-contaminated soil. We also expected to reveal the possible mechanism for the affected phytoremediation efficiency induced by PGPR. We used three kinds of contaminated soils (Ni-contaminated soil, pyrene-contaminated soil and pyrene-Ni co-contaminated soil) to conduct this pot study. After harvest, plants growth indicators, polyphenol oxidase (PPO) activity and soil microbial community structure of each treatment were investigated to explain the different dissipation rates of pyrene and removal rates of Ni between treatments with and without PGPR. The results showed that PGPR-inoculated S. triqueter increased dissipation rates of pyrene and removal rates of Ni in all three contaminated soils, among which Ni removal rates in Ni single contaminated soil was elevated most significantly, from 0.895‰ to 8.8‰, increasing nearly 9 folds. However, Ni removal rate efficiency in co-contaminated soil was weakened because more toxic and complicated co-contaminated soil restrained plant growth and Ni absorption. We also observed that co-contamination harmed the soil microbial community more severely than that in single pyrene or Ni contaminated soil through phospholipid fatty acids analysis. Furthermore, dissipation rates of pyrene and removal rates of Ni were found positively correlated to the PPO activity and the abundance of branched and saturated fatty acids reflected by Pearson correlation analysis.

Zhang X ，Su C ，Liu X ，Liu Z ，Liang X ，Zhang Y ，Feng Y ... -  《-》

Responses of Scirpus triqueter, soil enzymes and microbial community during phytoremediation of pyrene contaminated soil in simulated wetland.

The aim of this study was to determine the enhancement of Scirpus triqueter in the dissipation of pyrene and the interaction of pyrene with plant, soil enzymes and microbial community. The results indicated that the dissipation ratios of pyrene in the rhizospheric and non-rhizospheric soil were 64.65 ± 3.86% and 54.49 ± 2.74%, respectively, and were higher than that in the unplanted soil (42.60 ± 0.71%) at 80 d after planting S. triqueter. The pyrene was toxic to S. triqueter, as evidenced by growth inhibition in height, diameter, shoot number and biomass during the planting period. The activities of dehydrogenase decreased significantly at the presence of pyrene in soils, and increased remarkably with the introduction of S. triqueter. It was found that the pyrene addition increased the ratios of fungal/total fatty acids and gram-positive/gram-negative, but the presence of S. triqueter decreased the ratios of gram-positive/gram-negative. A larger stress level was found in the pyrene treated soils without S. triqueter. The ratio of aerobic/anaerobic bacteria decreased with increasing pyrene concentration, but increased when S. triqueter was planted. The principal analysis of phospholipid fatty acid signatures revealed that microbial community structures in the rhizospheric and non-rhizospheric soil were similar, but different from those in the unplanted and control soil.

Zhang X ，Liu X ，Liu S ，Liu F ，Chen L ，Xu G ，Zhong C ，Su P ，Cao Z ... -  《-》

Distribution by influence factors of pyrene removal in chemical enhancers assisted microbial phytoremediation of Scirpus triqueter in co-contaminated soils.

Zheng K ，Fan J ，Hu X ，Zhang X ，Liu X ，Shen J ... -  《-》