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Xie X.,Zhejiang University | Liao M.,Zhejing University | Liao M.,Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition | Yang J.,Zhejing University | Yang J.,Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition
Shengtai Xuebao/ Acta Ecologica Sinica | Year: 2011

Polycyclic aromatic hydrocarbons (PAHs) is one kind of persistent organic pollutants in environment, some previous researches have indicated plant could facilitate the dissipation of PAHs in contaminated soil. Phytoremediation is an important measure to remove organic pollutants from contaminated soil, and the root secretion of plant is considered to be closely related to the mechanisms of phytoremediation to organic pollutants. It is in favor of revealing the mechanisms of remediation by studying the characteristics of root exudates of plant with phytoremediation potential under the stress of pollutant. In the present research, pyrene and ryegrass (Lolium perenne L.) which has been testified to be tolerant to PAHs dtress were selected as studied objects. A solution culture experiment with series of pyrene concentration was conducted to investigate the effects of pyrene on low molecule weight organic compounds in the root exudates of ryegrass (Lolium perenne L.). The series concentration of pyrene in culture solution were designed as 0 mg/L, 3 mg/L, 6 mg/L and 9 mg/L. The results showed that, ryegrass had stronger tolerance to pyrene stress and grew well in culture solution spiked with 9 mg/L pyrene. Despite the biomass raised appreciably at relative low pyrene concentrations treatment (<3 mg/L) and reduced at relative high pyrene concentrations treatments (>3 mg/L), no significant changes of ryegrass biomass were found in all pyrene stress treatment (P<0.05). At the pyrene spiked levels of 3 mg/L, 6 mg/L and 9 mg/L pyrene stress, the organic acids, including oxlic acid, lactic acid and malic acid, were found in the root exudates of ryegrass, such component of organic acid in root exudates of ryegrass was stabilization in all pyrene stress treatment, but oxlic acid was the main composition of organic acid in root exudates of ryegrass, with a percentage greater than 97 %, and its content increased significantly with the increase of pyrene spiked level (P<0.05). Compared with control treatment (0 mg/L), oxlic acid content in root exudates of ryegrass increased from 24. 6 mg/kg to 53. 7 mg/kg in 9 mg/L pyrene treatment. The content of carbohydrate in root exudates of ryegrass raised appreciably at relative low pyrene spiked level (<3 mg/L) and reduced at relative high pyrene spiked level (> 3 mg/L), the highest carbohydrate content in root exudates took on 3 mg/L pyrene treatment, but the differences of carbohydrate content in root exudates were insignificant in all pyrene treatments (P <0. 05). Total amount of amino acids secreted increased significantly with the pyrene concentration increase, which were 1. 37, 2. 02 and 2. 65 times than that of control treatment (0 mg/L) under 3 mg/L, 6 mg/L and 9 mg/L pyrene treatment, respectively. Data also indicated that 19 types of familiar amino acids were found in root exudates of ryegrass and the component of amino acids in root exudates of ryegrass was stabilization under all pyrene stress treatments, but the each content of 19 types of amino acids examined was different in those root exudates under the stress of different pyrene concentration. The contents of all amino acid in those root exudates was increased with the pyrene concentration increase, especially, the contents secreted of threonine, serine, proline, glycine, alanine, histidine and ornithine increased significantly among 19 types of amino acids and the differences were significantly among different treatments with different pyrene concentration (P<0.05).


Fu X.T.,Zhejiang University | Fu X.T.,Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition | Fu X.T.,Key Laboratory of Polluted Environment Remediation and Ecological Health | Zhang L.P.,Zhejiang University | And 11 more authors.
Water Resources | Year: 2012

The economic forest management is one of the main land use models on low hill gentle slope. In order to investigate the soil erosion properties of bare slope under economic forest, dynamic simulation on hydraulic characteristic values of overland flow was carried out under 0. 5 mm min-1, 1. 2 mm min-1 and 1. 8 mm min-1 rainfall intensities. Results indicated that runoff shear stress increased with increasing of slope length and their relationship can be described by quadratic equation. There were abnormal points at the length of 4 m and 5. 5 m under rainfall intensity of 1. 8 mm min-1. The shallow flow was pseudo-laminar flow under 0. 5 mm min-1, 1. 2 mm min-1 and 1. 8 mm min-1 rainfall intensities, and the runoff at upslope was sluggish flow then changed to torrential flow at downslope with increasing of slope length. Critical Reynolds number varied from sluggish flow to torrential flow with 1. 8 mm min-1 rainfall intensity and was more than that under 0. 5 mm min-1. Reynolds number can be estimated by power function of slope length. And there was a positive correlation between runoff shear stress and both Froude number Fr and Reynolds number Re. We hope this study can provide scientific gist for soil erosion control under economic forest. © 2012 Pleiades Publishing, Ltd.


Liao M.,Zhejiang University | Liao M.,Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition | Ma A.-L.,Zhejiang University | Ma A.-L.,Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition | Xie X.-M.,Zhejiang University
Huanjing Kexue/Environmental Science | Year: 2011

One Pseudomonas diminuta strain M5R14 was selected as object in the present study, which was isolated from the tame sludge in water course of Pesticide Factory of Hangzhou and could degrade a variety of strains of synthetic pyrethroid insecticides. The inner and extra-cell crude enzyme of Pseudomonas diminuta strain M5R14 prepared by ultrasonic break up and centrifugal separation methods, and the characteristics of crude pyrethroid pesticide-degrading enzyme were primary studied. The results showed that pyrethroid pesticides degrading enzyme excreted from the strain of was intracellular enzyme, the best pH for bifenthrin, fenpropathrin and cypermethrin degradation was 6.5, as well as the most appropriate temperature was 35°C. Besides, the Michaelis constant and maximum degradation rate varied due to pyrethroid species. The Michaelis constant to such 3 pyrethroid pesticides were 4162.73, 1092.57, 1171.97 μmol/L respectively, and the maximum degradation rate to such 3 pyrethroid pesticides were 0.152, 0.038, 0.043 μmol/(min·mg) protein. The degradation process of crude degrading enzymes to such 3 pyrethroid pesticides was fitted for first-order kinetic equation and the half life (t1/2) were 119.51, 113.63, 108.30 min, respectively. Crude degrading enzymes for the three pyrethroid insecticides could be maintained high degradation activity when the pH ranging from 5.0 to 8.0, and the temperature was 20°C to 50°C, indicating the degrading enzymes were with large scope of pH stability and thermalstability. Therefore, there's higher potential in controlling the residuals of synthetic pyrethroid insecticides.


Liao M.,Zhejiang University | Liao M.,Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition | Xie X.-M.,Zhejiang University | Xie X.-M.,Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition | And 10 more authors.
Chinese Journal of Applied Ecology | Year: 2013

By using balance reaction method, this paper studied the adsorption characteristics and thermodynamic properties of DNA on four kinds of red soil colloids (organic matter-contained coarse clay, organic matter-removed coarse clay, organic matter-contained fine clay, and organic matterremoved fine clay). The DNA adsorption on the four red soil colloids was a process of fast reaction, and the adsorption isotherms were conformed to the Langmuir equation, with the corresponding correlation coefficient (r2) being 0.974, 0.991, 0.958, and 0.975, respectively. The maximum adsorption amount of DNA on the colloidal particles followed the order of organic matter-contained fine clay & gt; organic matter-removed fine clay > organic matter-contained coarse clay & gt; organic matter-removed coarse clay, implying that the size and organic matter content of colloidal particles played an important role in DNA adsorption. Electrolyte concentration and type and adsorption system pH were the main factors affecting the DNA adsorption on the four soil colloids. Within a definite electrolyte concentration range (NaCl < 60 mmol · L-1 and CaCl2 < 10 mmol· L-1), the adsorption amount of DNA on the red soil colloids increased significantly with the increase of electrolyte concentration. As compared with sodium ion, calcium ion had a greater promotion effect on the DNA adsorption, but the effect decreased significantly with the increase of adsorption system pH. The DNA adsorption on the organic matter-contained red soil colloids was an endothermic reaction, while the DNA adsorption on the organic matter-removed red soil colloids was an exothermic reaction. The DNA adsorption on the red soil colloids was a process of entropy increase.


Zhang L.-P.,Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition | Zhang L.-P.,Ministry of Education Key Laboratory of Polluted Environment Remediation and Ecological Health | Zhang L.-P.,Zhejiang University | Fu X.-T.,Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition | And 5 more authors.
Chinese Journal of Applied Ecology | Year: 2012

To understand the load characteristics and related mechanisms of surface runoff on two management types of bamboo forests(bamboo timber forest and bamboo shoot forest) slopes(gradient 20°) in Zhejiang Province, this study measured the runoff volume, sediment yield, its total nitrogen(TN) and total phosphorus(TP) concentrations of runoff under six artificial simulated rainfall intensity(31.8-114.0 mm·h-1). In bamboo timber forest, the total runoff volume and runoff coefficient were higher, but the runoff sediment content and the total sediment yield were far lower, as compared with those in bamboo shoot forest. The runoff TN concentration in bamboo shoot forest decreased with increasing rainfall intensity. Under the same rainfall intensity, the runoff TN concentration in bamboo shoot forest was 5-6 times of that in bamboo timber forest. The runoff TP concentration was higher in bamboo timber forest than in bamboo shoot forest, but the TP loss from the sediment runoff in bamboo shoot forest was hundreds times of that in bamboo timber forest. During the processes of the TN and TP losses from the sediment runoff, the TN and TP concentrations at the prophase of runoff yield played a cardinal role, while the runoff volume and sediment yield at the anaphase played a decisive role.


Zhang M.-K.,Zhejiang University | Zhang M.-K.,Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition | Liu Z.-Y.,Zhejiang University | Wang H.,Zhejiang University
Communications in Soil Science and Plant Analysis | Year: 2010

Human exposure to toxic heavy metals via dietary intake is of increasing concern. Heavy-metal pollution of a rice production system can pose a threat to human health. Thus, it was necessary to develop a suitable extraction procedure that would represent the content of metal available to rice plants (Oryza sativa L.). The aim of this study was to predict, on the basis of single extraction procedures of soil heavy metals, the accumulation of heavy metals (cadium, lead, copper, and zinc) in rice plants. Six extracting agents [Mehlich 1, Mehlich 3, EDTA (ethylenediaminetetraacetic acid), DTPA-TEA (diethylenetriaminepentaacetic acid-triethanolamine), ammonium acetate (NH4OAc), and calcium chloride (CaCl2)] were tested to evaluate the bioavailability of heavy metals from paddy soils contaminated with lead-zinc mine tailings to rice. The extraction capacity of the metals was found to be of the order EDTA > Mehlich 3 > Mehlich 1 > DTPA-TEA > NH4OAc > CaCl2. The correlation analysis between met-als extracted with different extractants and concentrations of the metals in the grain and stalk of the plant showed positive correlations with all metals. The greatest values of correlation coefficients were determined between the NH4OAc- and CaCl2-soluble fractions of soil and contents in plants in all four metals studied. Therefore, NH4OAc and CaCl2 were the most suitable extractants for predicting bioavailability of heavy metals in the polluted soils to rice. The results suggested that uptake of heavy metals by rice was mostly from exchangeable and water-soluble fractions of the metals in the soils. Soil-extractable metals were more significantly correlated with metal accumula-tion in the stalk than in the grain. The pH had more significant influence on availability of heavy metals in the soils than total content of metals and other soil properties. The bioavailability of metals for rice plants would be high in acidic soils. © Taylor & Francis Group, LLC.


Hu L.,Zhejiang University | Hu L.,Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition | Hu L.,Cornell University | McBride M.B.,Cornell University | And 14 more authors.
Environmental Research | Year: 2011

Our aim was to investigate rhizosphere effects on the chemical behavior of Cd. This was done in a glasshouse experiment, where two rice cultivars (Zhenong54 and Sixizhan) were grown in soil spiked with cadmium (Cd) at two levels, 3.9±0.5 and 8.3±0.5mgkg-1 soil, placed in a rhizobox until ripening stage. Chemical forms of cadmium near the root surface were then assessed using a sequential extraction procedure (SEP). There were significant differences in Cd species, especially exchangeable Cd (EXC-Cd) between the two rice cultivars as affected by rice roots. The lowest EXC-Cd with Zhenong54 appeared in the near-rhizosphere area with little difference between tillering stage and ripening stage while Sixizhan had its lowest EXC-Cd concentration in the root compartment. Both cultivars had slight changes in the Fe/Mn oxide-bound fraction of Cd (FMO-Cd) at the grain ripening stage while the control treatments without plants had a significant increase in FMO-Cd at the same time, indicating a transformation from a less bioavailable form (FMO-Cd) to more bioavailable forms (EXC-Cd). Soil microbial biomass in the vicinity of the root surface had opposite trends to some extent with EXC-Cd, partly because of the root-induced changes to bioavailable Cd. Unlike Zhenong54, Sixizhan had a higher Cd concentration in the root, but only a small proportion of Cd translocated from the root to grain. © 2011 Elsevier Inc.

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