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Li T.,Peking University | Li T.,Key Laboratory of Water and Sediment science | Ding Y.,Peking University
PLoS ONE | Year: 2017

The regional policy in China is shifting from solely gross domestic product (GDP) orientation to development that is more balanced between economic growth and ecological protection, as well as achieving equality among regions. Using land use maps and the adjusted value coefficients to assess ecosystem service values (ESV) for the 1980s, 1995, 2000, and 2010, we estimated the ESV in Shaanxi Province for different years, and characterized the spatial and temporal distribution of ESV and GDP. The results demonstrated that the total value of ecosystem services in Shaanxi Province increased from 208.95 billion Yuan in the 1980s to 309.76 billion Yuan in 2010. Variation Coefficient (Cv) and Theil index (T) were used to reflect the disparities of GDP or ESV within the study area. The values of Cv in descending order are GDP, ESV per capita, ESV, and GDP per capita. The Theil indexes of GDP were much greater than the ones of ESV. Variations of Cv and T showed that disparity in GDP kept increasing from the 1980s to 2000, then decreased; while no significant change in regional disparity of ESV were detected in parallel. The cities with higher GDP usually contributed little to ESV, and vice versa. The variation in GDP and ESV, in terms of the prefectural totals and per capita values, increased from the 1980s to 2010. This study provides an accessible way for local decision makers to evaluate the regional balance between economic growth and ecosystem services. © 2017 Li, Ding. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Yang Q.-Z.,Peking University | Yang Q.-Z.,Shandong Polytechnic University | Chang Y.-Y.,Peking University | Chang Y.-Y.,Key Laboratory of Water and Sediment science | And 2 more authors.
Water Research | Year: 2013

It is necessary to develop "green" disinfection technology which does not produce disinfection by-products. Lysozyme-layered double hydroxide nanocomposites (LYZ-LDHs) were prepared by intercalating LYZ in LDH for the first time. Their antibacterial activity was evaluated using staphylococcus aureus as a target. The bacteria removal mechanism was also studied. Characterization of LYZ-LDHs by X-ray diffraction and Fourier transform infrared spectroscopy indicated that LYZ was successfully intercalated in LDH, compressed and deformed without secondary structural change. LYZ-LDHs showed excellent bactericidal effectiveness against staphylococcus aureus. The antibacterial performance of LYZ-LDHs was found to be affected by the LYZ/LDH ratio and the pH of the bacteria-containing water. The bacteria removal efficiency of LYZ-LDHs with LYZ/LDH mass ratio of 0.8 was consistently above 94% over the pH range of 3-9. LYZ-LDHs adsorbed bacteria to their surface by LDH and then killed them by the immobilized LYZ. This new material integrated the bactericidal ability of LYZ and adsorption ability of LDH. Moreover, the antibacterial ability of LYZ-LDHs was persistent and not limited by the adsorption capacity. © 2013 Elsevier Ltd.


Zhao H.-Z.,Peking University | Zhao H.-Z.,Key Laboratory of Water and Sediment science | Chang Y.-Y.,Peking University | Chang Y.-Y.,Key Laboratory of Water and Sediment science | And 2 more authors.
Journal of Solid State Electrochemistry | Year: 2013

Electrodes modified with iron porphyrin and carbon nanotubes (FeP-CNTs) were prepared and used for CO2 electroreduction. The adsorption of iron porphyrin onto the multiwalled carbon nanotubes was characterized by scanning electron microscopy and ultraviolet and visible spectroscopy. The electrochemical properties of the modified electrodes for CO2 reduction were investigated by cyclic voltammetry and CO2 electrolysis. The FeP-CNT electrodes exhibited less negative cathode potential and higher reaction rate than the electrodes modified only with iron porphyrin or carbon nanotubes. A mechanism of the synergistic catalysis was proposed and studied by electrochemical impedance spectroscopy and electron paramagnetic resonance. The direct electron transfer between iron porphyrin and carbon nanotubes was examined. The current study shed light on the mechanism of synergistic catalysis between CNTs and metalloporphyrin, and the iron porphyrin-CNT-modified electrodes showed great potential in the efficient CO2 electroreduction. © 2013 Springer-Verlag Berlin Heidelberg.


Yao S.,Peking University | Yao S.,Key Laboratory of Water and Sediment science | Ni J.,Peking University | Ni J.,Key Laboratory of Water and Sediment science | And 4 more authors.
Bioresource Technology | Year: 2013

A psychrotrophic heterotrophic nitrifying-aerobic denitrifying bacterium was newly isolated and identified as Acinetobacter sp. with phenotypic and phylogenetic analysis. The strain possessed excellent tolerance to low temperature with 20°C as its optimum and 4°C as viable. Moreover, ammonium, nitrite and nitrate could be removed efficiently under low-temperature, solely aerobic conditions with little accumulation of intermediates. The average removal rate at 10°C reached as high as 3.03, 2.51 and 1.88mgNL-1h-1 for ammonium, nitrite and nitrate respectively. N2 was produced through heterotrophic nitrification and aerobic denitrification via nitrite but N2O was never detected in the whole process. Nitrogen balance analysis indicated that N2 and intracellular nitrogen were two major fates of the initial ammonium, accounting for 32.4 and 49.2%, respectively. Further aerated batch test demonstrated efficient removal of COD and TN from synthetic wastewater, which implied promising practical application of the present strain. © 2013.


Xue A.,Peking University | Xue A.,Key Laboratory of Water and Sediment science | Shen Z.-Z.,Peking University | Shen Z.-Z.,Key Laboratory of Water and Sediment science | And 4 more authors.
Journal of Hazardous Materials | Year: 2013

Conventional zerovalent iron (ZVI) technology has low arsenic removal efficiency because of the slow ZVI corrosion rate. In this study, microbial fuel cell (MFC)-zerovalent iron (MFC-ZVI) hybrid process has been constructed and used to remove arsenite (As(III)) from aqueous solutions. Our results indicate that the ZVI corrosion directly utilizes the low-voltage electricity generated by MFC in the hybrid process and both the ZVI corrosion rate and arsenic removal efficiency are therefore substantially increased. The resultant water qualities are compliant with the recommended standards of EPA and WHO. Compared to the ZVI process alone, the H2O2 generation rate and output are dramatically improved in MFC-ZVI hybrid process. Strong oxidants derived from H2O2 can rapidly oxidize As(III) into arsenate (As(V)), which helps to improve the As(III) removal efficiency. The distribution analysis of As and Fe indicates that the As/Fe molar ratio of the flocs in solution is much higher in the MFC-ZVI hybrid process. This phenomenon results from the different arsenic species and hydrous ferric oxides species in these two processes. In addition, the electrosorption effect in the MFC-ZVI hybrid process also contributed to the arsenic removal by concentrating As(V) in the vicinity of the iron electrode. © 2013.


Hou X.,Peking University | Hou X.,Key Laboratory of Water and Sediment science | Liu S.,Peking University | Liu S.,Key Laboratory of Water and Sediment science | And 2 more authors.
Water Research | Year: 2015

The high aggregation ability of anammox sludge has been extensively observed, but the cause for their aggregation is challenging. Here the structure and composition of extracellular polymeric substance (EPS) excreted from anammox sludge were systematically investigated to interpret the high aggregation ability. We combine results of contact angle, zeta potential and surface thermodynamics analysis as well as the following DLVO theory to address this issue. The results show that hydrophobic interaction is the main force determining the aggregation of anammox sludge. To go insight into inherent mechanism, Fourier transform infrared (FTIR) and x-ray photoelectron (XPS) spectroscopy were conducted and demonstrated there were comparatively few hydrophilic functional groups in the EPS of anammox sludge, compared to that of activated sludge, nitrifying and denitrifying sludge. Further, amino acid composition and secondary structure analyses of protein indicated that large amounts of hydrophobic amino acids and high level of protein loose structure for exposing inner hydrophobic groups of protein in EPS significantly contributed to the hydrophobic interaction and further to the high aggregation ability of anammox sludge, which is the critical finding of this work. This investigation is useful for understanding anammox bacteria and then for accelerating the application of the anammox process in wastewater treatment. © 2015 Elsevier Ltd.


Zhao H.-Z.,Peking University | Zhao H.-Z.,Key Laboratory of Water and Sediment science | Zhang Y.,Peking University | Zhang Y.,Key Laboratory of Water and Sediment science | And 4 more authors.
Journal of Power Sources | Year: 2012

Carbon dioxide (CO 2) is now known to be a major cause of global warming, and the reduction of its atmospheric concentration has therefore become a critical issue. The amount of CO 2 discharged from the degradation process of waste organic substances is both tremendous and neglected. Here, an environmentally friendly method to achieve the fixation of the CO 2 released from the degradation of waste carbonaceous substances has been investigated. A series-connected microbial fuel cell (MFC) stack is used to electro-reduce the CO 2 to formic acid in situ utilizing the electricity generated from the degradation of the carbonaceous substances in the anodic chambers of the MFC stack. Consequently, formic acid at 4.27 mg L -1 h -1 is produced, and a Faraday efficiency of 64.8% is achieved. This technology will be helpful in recycling and reusing the carbon in wastewaters or wastes in the absence of external energy input, thereby promoting the virtuous cycle of carbon. Highlights: An MFC-stack-driven MEC is used to electro-reduce CO 2 to formic acid. The MFC-generated electricity is utilized in situ to reduce the MFC-produced CO 2. Formic acid at 4.27 mg L -1 h -1 is produced with a Faraday efficiency of 64.8%. © 2012 Elsevier B.V. All rights reserved.


Sui X.,Key Laboratory of Water and Sediment science | Sui X.,Stockholm Environment Institute | Ji G.,Key Laboratory of Water and Sediment science
Journal of Hazardous Materials | Year: 2010

An ultrasound-enhanced elution system employing Triton X-100 solutions was used for remedying aging soils contaminated with super heavy oil. The effect of varying the ultrasonic power density on the elution of the oil and three characteristic biomarkers was analyzed using GC/MS and FTRS. The oil and biomarkers remaining in treated soils decreased as a similar first-order function of increasing ultrasonic power density. Elution of the three biomarkers in the absence of ultrasound was closely related to carbon numbers in the marker: smaller molecules were more readily eluted. This trend was reversed upon application of ultrasound at higher power densities, with improved elution of molecules containing a greater carbon numbers. The two ratios, both 22S/(22S + 22R) of C 26-34 17α 25-norhopanes and 20S/(20S + 20R) of C 26-28 triaromatic steroids, in treated soils decreased with increasing power density from 20 to 100 W L -1. The results of SEM, FTRS, XRD, and energy spectroscopy experiments indicated that the mineral and chemical compositions of soils eluted at power densities greater than 60 W L -1 closely resembled clean soils. © 2009 Elsevier B.V. All rights reserved.


Ji G.,Key Laboratory of Water and Sediment science | Guo F.,The Key Laboratory of Urban Human Residential Environmental Science and Technology
Chemosphere | Year: 2010

An ultrasound-enhanced elution system using water at a temperature of 70 °C was employed to remove severely biodegraded heavy oil (SBHO) from weathered soil. The effect of varying the ultrasonic power density from 0 to 100 W L-1 on the elution of SBHO and three characteristic biomarkers (C26-34 17α 25-norhopanes, C26-28 triaromatic steroids (TAS), and C27-29 methyl triaromatic steroids (MTAS) was analyzed using GC/MS, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The amount of SBHO and biomarkers present in the treated soils and eluent had significant negative correlation with increasing ultrasonic power density. Elution of the three biomarkers was closely related to the number of C atoms in the marker: C26-34 17α 25-norhopanes with more carbon numbers and MTAS homologs with less carbon numbers were more readily eluted at higher power densities. The smaller TAS species were more readily eluted at a power density of less than 60 W L-1, while larger TAS species displayed improved elution at power densities greater than 60 W L-1. SEM images of samples treated at higher power densities revealed a more compact SBHO accumulation layer at the water-soil interface. The results of XRD and energy spectroscopy experiments indicated that ultrasound at a power density of 20 W L-1 was helpful for the formation and sedimentation of calcite, although this effect disappeared at higher power of greater than 60 W L-1. © 2010 Elsevier Ltd. All rights reserved.


Bai X.,Institute of Chemical Technology | Ye Z.-f.,Key Laboratory of Water and Sediment science | Li Y.-f.,Institute of Chemical Technology | Zhou L.-c.,Institute of Chemical Technology | Yang L.-q.,Institute of Chemical Technology
Process Biochemistry | Year: 2010

In this work, a new and economical way to prepare macroporous poly(vinyl alcohol) (PVA) foam was explored by adding calcium carbonate as a pore-forming agent and using epichlorhydrin as a chemical crosslinking agent to improve foam stability. The mixture for foam formation has been optimized to obtain macroporous PVA foam carriers with uniform apertures, narrow distribution of pore sizes, and good elasticity. The crosslinked PVA foam (CPVAF) carrier demonstrated better chemical and thermal stability, as well as larger specific surface area and diffusion coefficients than the traditional PVA (TPVA) carrier. Nitrifying bacteria were used to test the suitability of CPVAF and TPVA carriers for immobilized microorganisms. CPVAF carriers supported higher biomass density and microbial activity than TPVA carriers. At the same biomass density, the higher nitrification rate of CPVAF carriers was attributed to excellent mass transfer of the substrate (and oxygen) between the bulk solution and the immobilized microorganisms. © 2009 Elsevier Ltd. All rights reserved.

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