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Wei J.,Institute of Disaster Prevention | Qi J.,Beijing Municipal Research Institute of Environmental Protection | Qi J.,National Urban Environment Pollution Control Engineering Techniques Research Center | Wu Y.,Institute of Disaster Prevention | And 2 more authors.
Applied Mechanics and Materials | Year: 2013

GA-Bp network model was proposed. GA was used to optimize the initial real values population of Bp network, and optimizing crossover fraction was fulfilled. In addition, the modified GA-Bp was applied to predict the deformation of the surrounding rock around tunnels. © (2013) Trans Tech Publications, Switzerland. Source


Xia T.,Beijing Municipal Research Institute of Environmental Protection | Xia T.,National Urban Environment Pollution Control Engineering Techniques Research Center | Pan J.,Beijing Municipal Research Institute of Environmental Protection | Pan J.,Capital Normal University | And 8 more authors.
Research of Environmental Sciences | Year: 2015

To assess the feasibility of persulfate oxidation for predicting the bioavailability of polycyclic aromatic hydrocarbons (PAHs) in soils polluted by the coking process, persulfate oxidation was used to determinate bioavailable fraction of 16 priority PAHs (US EPA) in surface soils from a coking plant in Beijing, China. The changes in contents and components of the soil organic matter (SOM) were investigated before and after oxidation. The results showed: 1) The total concentrations of PAHs in seven test soils were between 10.80 and 249.00 mg/kg, dominated by high molecular weight PAHs. There was a significant positive correlation between the PAHs concentrations for different ring groups and the content of SOM in soils, according with a logarithmic equation (R2 values ranged from 0.653 to 0.798). 2) The bioavailability of PAHs was expressed as the ratio of oxidated PAHs concentration to initial PAHs concentration. Bioavailability of 2-3 ring PAHs was 0.46, higher than 4 ring PAHs (0.22) and 5-6 ring PAHs (0.28). High SOM content and high molecular weight of PAHs caused the decrease in PAHs bioavailability. 3) There was a significant positive linear relationship between initial PAHs concentrations and residual PAHs concentrations for different ring groups (R2 values ranged from 0.991 to 0.994). Thus, an empirical equation could be built to calculate the PAHs bioavailability based on the initial PAHs concentrations. 4) After persulfate oxidation, average SOM content decreased by 23.0%, and fourier transform infra-red (FTIR) spectroscopy showed that aliphatic carbons characterized by the absorption peak at 1448 cm-1 might be the main component of the oxidized soft carbon in soils. A slight increasing by 0.88% to 11.62% for aromatic carbon in relative absorbance values provided the evidence that the persulfate oxidation would make the residual SOM more condensed and hydrophobic. In summary, persulfate oxidation could be adopted to determine PAHs bioavailability rapidly in coking plant soils, especially using the empirical equation to predict soil PAHs bioavailability based on its initial concentration. ©, 2015, Editorial department of Molecular Catalysis. All right reserved. Source


Xia T.,Beijing Municipal Research Institute of Environmental Protection | Xia T.,National Urban Environment Pollution Control Engineering Techniques Research Center | Jiang L.,Beijing Municipal Research Institute of Environmental Protection | Jiang L.,National Urban Environment Pollution Control Engineering Techniques Research Center | And 5 more authors.
Huagong Xuebao/CIESC Journal | Year: 2014

Soils contaminated by polycyclic aromatic hydrocarbons (PAHs) were sampled from a typical coking plant in southeast Beijing, China, and tested by thermal desorption under the controlled condition of 50-450°C heating temperature and 30 min constant residual time using an indirect rotary heating laboratory equipment. After each thermal desorption program, decontamination level, residual contamination of 16 EPA priority PAHs and changes in soil characteristics, i.e. total organic carbon (TOC), dissolved organic carbon (DOC), surface area (SA) and soil particle size distribution, were investigated for low PAHs concentration soil (S1) and high PAHs concentration soil (S2), respectively. The results showed that with increasing heating temperature, the decontamination level of LPAHs (low molecular weight PAHs, sum of Nap to Pyr), HPAHs (high molecular weight PAHs, sum of BaA to BgP) and total PAHs increased significantly (p<0.01), which was governed successively by heating temperature, PAHs molecular weight and contaminant concentration due to the F values based on a multivariate analysis. The decontamination level began to increase significantly around the melting point and for the isothermal desorption the significant difference of decontamination level between LPAHs and HPAHs existed only below 300°C for S1 and 400°C for S2. It was revealed that the thermal desorption process were evidently associated with the form of PAHs in soils and the bioavailable PAHs were almost removed at 200-300°C. The decontamination level reached 91.3% and 98.4% at 450°C heating temperature where the eight target residual PAHs concentration ranged from 0.07 mg · kg-1 to 0.71 mg · kg-1 for S1 and from 0.26 mg · kg-1 to 40.20 mg · kg-1 for S2, whereas several PAHs species still exceeded the corresponding screening levels for soil environmental risk assessment of residential land in Beijing. After thermal desorption at 450°C, it was also found that TOC decreased by 51.4% (p<0.05) for S1 and by 23.1% (p<0.05) for S2, simultaneously with an inverse change trend in DOC between S1 and S2. Moreover, surface areas of S1 and S2 after heating were smaller than that before heating, which coincided with the slight increase in soil particle size and agglomeration existing at an electron scanning program. © All Rights Reserved. Source


Jiang L.,Beijing Municipal Research Institute of Environmental Protection | Jiang L.,National Urban Environment Pollution Control Engineering Techniques Research Center | Jiang L.,Beijing Key Laboratory for Risk Modeling and Remediation of Contaminated Sites | Jia X.-Y.,Beijing Municipal Research Institute of Environmental Protection | And 14 more authors.
Research of Environmental Sciences | Year: 2013

Based on the previous results of contamination survey on a coking plant in Beijing, the effects of uncertainty of 15 exposure parameters and soil pollutant concentrations on human health risk assessment of benzene and benzo[a]pyrene were investigated with the methods of probabilistic risk assessment (PRA). Results showed that the risk values of PRA, which was located at the 95th centile in the probabilistic range of risk values, were lower than that of deterministic risk assessment (DRA) of benzene and benzo[a]pyrene in both surface and subsurface soil through single and total exposure pathways. The total risk calculated by PRA ranged from 1.5×10-8 to 6.9×10-3 for benzene and 2.3×10-9 to 2.2×10-3 for benzo[a]pyrene, and the values were located at the 95th centile in the probabilistic range of risk were 3.8×10-4 and 1.1×10-4, respectively. The total risks conducted by DRA were located at the 96.8th and 99.1th centiles in the probabilistic range of risk, which were 1.5 and 3.2 times of the values by PRA. This indicated that the methods of DRA overestimated the real risk. The results of parameter sensitivity analysis revealed that the concentration of benzene in the subsurface soil (94.63%) and the adult exposure duration (4.12%) contributed the most to the uncertainty in benzene risk assessment, and the concentration of benzo[a]pyrene in the surface soil (92.3%), adult exposure duration (2.40%), soil ingestion rate (2.12%) and child exposure duration (1.21%) contributed the most to the uncertainty in benzo[a]pyrene risk assessment. Source

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