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Zhong S.-Q.,Hengyang Normal University | Xu J.-M.,Zhejiang University | Xu J.-M.,Zhejiang Province Key Laboratory of Subtropic Soil and Plant Nutrition
Chinese Journal of Applied Ecology | Year: 2013

A pot experiment was conducted to study the effects of adding 100 and 500 mg·kg-1 of exogenous iron (Fe) on the lead (Pb) accumulation in Typha latifolia growing on a soil with 0, 100, 500 and 1000 mg·kg-1 of Pb, respectively. In treatment 500 mg Fe·kg-1, the Pb concentration in T. latifolia shoots and roots was higher, compared with that in treatment 100 mg Fe·kg-1. When the soil Pb concentration was 1000 mg·kg-1, the Pb concentration in T. latifolia shoots and roots in treatment 500 mg Fe·kg-1 increased by 33.7% and 50.5%, respectively, compared with that in treatment 100 mg Fe·kg-1. The exchangeable Pb concentration in rhizosphere soil was 77.0%-114.6% higher in treatment 500 mg Fe·kg-1 than in treatment 100 mg Fe·kg-1. When the soil Pb concentration was 0, 100 and 1000 mg·kg-1, the root dry mass in treatment 500 mg Fe·kg-1 had a significant decrease, compared with that in treatment 100 mg Fe·kg-1. It was suggested that adding appropriate amount of Fe to Pb contaminated wetland soil could increase the availability of soil Pb and improve the Pb accumulation in plants. Source


Xie X.-M.,Zhejiang University | Liao M.,Yu Da University | Liao M.,Zhejiang Province Key Laboratory of Subtropic Soil and Plant Nutrition | Yang J.,Yu Da University | And 6 more authors.
Chemosphere | Year: 2012

The effect of ryegrass (Lolium perenne L.) root-exudates concentration on pyrene degradation and the microbial ecological characteristics in the pyrene contaminated soil was investigated by simulating a gradually reducing concentration of root exudates with the distance away from root surface in the rhizosphere. Results showed that, after the root-exudates were added 15d, the pyrene residue in contaminated soil responded nonlinearly in the soils with the same pyrene contaminated level as the added root-exudates concentration increased, which decreased first and increased latter with the increase of the added root-exudates concentration. The lowest pyrene concentration appeared when the root exudates concentration of 32.75mgkg-1 total organic carbon (TOC) was added. At the same time, changes of microbial biomass carbon (MBC, Cmic) and microbial quotient (Cmic/Corg) were opposite to the trend of pyrene degradation as the added root-exudates concentration increased. Phospholipid fatty acid (PLFA) analysis revealed that bacteria was the dominating microbial community in pyrene contaminated soil, and the changing trends of pyrene degradation and bacteria number were the same. The changing trend of endoenzyme-dehydrogenase activity was in accordance with that of soil microbe, indicating which could reflect the quantitative characteristic of detoxification to pyrene by soil microbe. The changes in the soils microbial community and corresponding microbial biochemistry characteristics were the ecological mechanism influencing pyrene degradation with increasing concentration of the added root-exudates in the pyrene contaminated soil. © 2012 Elsevier Ltd. Source


Xie X.-M.,Zhejiang University | Liao M.,Zhejing University | Liao M.,Zhejiang Province Key Laboratory of Subtropic Soil and Plant Nutrition | Yang J.,Zhejing University | Yang J.,Zhejiang Province Key Laboratory of Subtropic Soil and Plant Nutrition
Chinese Journal of Applied Ecology | Year: 2011

By simulating a gradually decreasing concentration of root exudates with the distance away from root surface in rhizosphere, this paper studied the effects of ryegrass(Lolium perenne) root exudates dose on the pyrene degradation and microbial ecological characteristics in a pyrenecontaminated soil. It was observed that with the increasing dose of ryegrass root exudates, the residual amount of soil pyrene changed nonlinearly, i. e., increased after an initial decrease. When the root exudates dose was 32.75 mg·kg-1 of total organic carbon, the residual pyrene was the minimum, indicating that the root exudates at this dose stimulated pyrene degradation significantly. In the meantime, soil microbial biomass carbon and microbial quotient had an opposite trend, suggesting the close relationship between pyrene degradation and soil microbes. In the test soil, microbial community was dominated by bacteria, and the bacteria had the same variation trend as the pyrene degradation, which indicated that the pyrene was degraded mainly by bacteria, and the effects of root exudates on pyrene degradation were mainly carried out through the effects on bacterial population. There was a similar variation trend between the activity of soil dehydrogenase, a microbial endoenzyme catalyzing the dehydrogenation of organic matter, and the soil microbes, which further demonstrated that the variations of soil microbes and their biochemical characteristics were the ecological mechanisms affecting the pyrene degradation in the pyrene-contaminated soil when the ryegrass root exudates dose increased. Source

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