Yu R.,Nanjing Southeast University |
Yu R.,University of Connecticut |
Smets B.F.,Technical University of Denmark |
Gan P.,University of Connecticut |
And 3 more authors.
Canadian Journal of Microbiology | Year: 2014
We investigated the seasonal and spatial variation in activity and density of the metabolically active in situ microbial community (AIMC) at a landfill leachate-impacted groundwater - surface water interface (GSI). A series of AIMC traps were designed and implemented for AIMC sampling and microbial activity and density examinations. Measurements were made not only at the level of bacterial domain but also at the levels of alphaproteobacterial Rhizobiales order and gammaproteobacterial Pseudomonas genus, both of which included a large number of iron-oxidizing bacteria as revealed from previous analysis. Consistently higher microbial activities with less variation in depth were measured in the AIMC traps than in the ambient sediments. Flood disturbance appeared to control AIMC activity distributions at the gradually elevated GSI. The highest AIMC activities were generally obtained from locations closest to the free surface water boundary except during the dry season when microbial activities were similar across the entire GSI. A clone library of AIMC 16S rRNA genes was constructed, and it confirmed the predominant role of the targeted alphaproteobacterial group in AIMC activity and composition. This taxon constituted 2%-14% of all bacteria with similar activity distribution profiles. The Pseudomonas group occupied only 0.1‰-0.5‰ of the total bacterial density, but its activity was 27 times higher than the bacterial average. Of the 16S rRNA sequences in the AIMC clone library, 7.5% were phylogenetically related to putative IOB, supporting the occurrence and persistence of active microbial iron oxidation across the studied iron-rich GSI ecosystem. Source
Ren Y.,CAS Research Center for Eco Environmental Sciences |
Kang S.,BCEG Environmental Remediation Co. |
Zhu J.,CAS Research Center for Eco Environmental Sciences
Journal of Material Cycles and Waste Management | Year: 2015
In the present work, we investigate the destruction efficiency of hexachlorobenzene (HCB) by milling with various reagents in a planetary ball mill under different milling conditions. Under the same conditions of mill rotary rate and charge ratio, the mixture of magnesium powder and aluminum oxide (Mg/Al2O3) was found best in promoting the destruction of HCB, which can be completed destroyed after 90 min grinding at a charge ratio of 20:1 (reagent/HCB, m/m), a ball mass/reagent mass ration of 30:1 and a mill rotation speed of 550 rpm. The ground samples were characterized and analyzed by X-ray fluorescence, gas chromatography (GC), X-ray diffraction and ion chromatography. The intermediate products, such as pentachlorobenzene, tetrachlorobenzene, trichlorobenzene isomers, dichlorobenzene and monochlorobenzene were detected by GC. Then the main dechlorination path way for HCB was proposed. With a series of verification experiments, the final degradation products of HCB were amorphous carbon and inorganic chlorine. Based on this study, Mg/Al2O3 has the potential to complete the innocuous treatment of chlorinated compounds. © 2015 Springer Japan Source
Du P.,Chinese Research Academy of Environmental Sciences |
Wang S.-J.,Beijing Municipal Research Institute of Environmental Protection |
Zhao H.-H.,Chinese Research Academy of Environmental Sciences |
Wu B.,Chinese Research Academy of Environmental Sciences |
And 5 more authors.
Huanjing Kexue/Environmental Science | Year: 2013
The influencing factors of benzene diffusion fluxes from sand and black soil to atmosphere were investigated using a flux chamber (30.0 cm×17.5 cm×29.0 cm). In this study, the benzene diffusion fluxes were estimated by measuring the benzene concentrations both in the headspace of the chamber and in the soils of different layers. The results indicated that the soil water content played an important role in benzene diffusion fluxes. The diffusion flux showed positive correlation with the initial benzene concentration and the benzene dissolution concentration for both soil types. The changes of air flow rate from 300 to 900 mL·min-1 and temperature from 20°C to 40°C resulted in increases of the benzene diffusion flux. Our study of benzene diffusion fluxes from contaminated soils will be beneficial for the predicting model, and emergency management and precautions. Source
Fang Z.-Q.,China University of Mining and Technology |
Gan P.,BCEG Environmental Remediation Co. |
Yang L.,China University of Mining and Technology |
Dai Z.-Y.,China University of Mining and Technology |
And 3 more authors.
Huanjing Kexue/Environmental Science | Year: 2013
The dissipative concentration test of VOCs in the remediation process of a typical contaminated site was operated, and three routes of exposure were set up for health risk assessment in the repair process. Analysis showed that carbon tetrachloride was the single pollutant with highest multi-route cumulative non-carcinogenic index, which was as high as 8.86E+01, and its contribution rate to the integrated non-carcinogenic effects was 74.45%. Respiratory exposure was the exposure route with highest multi-pollutant hazard index, which was 1.01E+02, accounting for 84.87% of the comprehensive risk index, and the index of integrated non-carcinogenic damage was 1.19E+02. 1, 2-dichloroethane was the single pollutant with highest multi-route cumulative carcinogenic index, which was as high as 3.08E-02, and its contribution rate to the integrated carcinogenic effects was 69.53%. Respiratory exposure was the exposure route with highest multi-pollutant hazard index, which was 3.96E-02, accounting for 89.39% of the comprehensive risk index, and the index of integrated carcinogenic damage was 4.43E-02. Source
Zhang X.,Nanjing Agricultural University |
Zhang X.,BCEG Environmental Remediation Co. |
Liang X.,Nanjing Agricultural University |
Zhan X.,Nanjing Agricultural University |
And 2 more authors.
Chinese Journal of Environmental Engineering | Year: 2013
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous, environmental organic pollutants. They have been of particular concern because some of them are highly carcinogenic and mutagenic for human and animals. The aim of this paper was to investigate the intercropping remediation of ryegrass and clover in phenanthrene-contaminated soil through pot experiments. Results indicated that ryegrass and clover grew well in the phenanthrene range of 0~50 mg/kg. Intercropping between ryegrass and clover enhanced phenanthrene uptake by ryegrass and clover roots, and root concentration factor in intercropping system was much higher than that in single-cropping system. Phenanthrene in soil decreased significantly over the incubation period because of biodecomposition and plant absorption. The effectiveness of intercropping remediation was better than that of single cropping remediation in heavily contaminated soil with a highest removal rate of 90.53%. Therefore, it is suggested that ryegrass and clover intercropping is a feasible technique for phytoremediating heavily PAH-contaminated soils. Source