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641.
Ismet ok Menekse Keski Donmez Mine Uner Erkan Demirkaya Bernhard Henkelmann Heqing Shen Jarmila Kotalik Karl-Werner Schramm 《Chemosphere》2009,76(11):1563-1571
Human breast milk offers the optimal nutrition for all infants and have been widely used in biomonitoring programs to assess human exposure to lipophylic environmental contaminants such as polychlorinated dibenzo-p-dioxins (PCDD), polychlorinated dibenzofurans (PCDF) and polychlorinated biphenyls (PCB). There are no previous reports from Turkey on chemically determined levels of PCDDs, PCDFs, and PCBs in human breast milk expressed as World Health Organization (WHO) toxic equivalents (TEQ). To get an overview of the levels of these contaminants in Turkish human milk, samples from 51 Turkish women living in the Ankara, İstanbul, Antalya, Kahramanmaraş, and Afyon provinces were analyzed by high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS) throughout 2007. The mean concentrations of WHOPCDD/F-TEQ and WHOPCB-TEQ of all samples from the five regions were 7.5 and 3.1 pg g−1 on a lipid basis, respectively. PCDD/F concentrations ranged between 0.78 and 29.3 pg WHO-TEQ g−1 fat (1.7 and 36.2 pg WHO-TEQ g−1 fat, respectively, including PCB). Of the five studied locations, the lowest levels of ∑TEQs (PCDD/F + PCB) were found in the Afyon (6.8 pg WHO-TEQ g−1 fat) and the highest in the Antalya (15.6 pg WHO-TEQ g−1 fat) province. The results have been discussed in terms of regions and PCDD/F and PCBs for which analyses had been made. The mean levels of PCDD/Fs and PCBs in Turkish human milk are comparable to that found in other countries. 相似文献
642.
This work provides an exploratory analysis on the relative importance of various factors controlling the fate and transport of volatile organic contaminants (in this case, TCE) from a DNAPL source zone located below the water table and into the indoor air. The analysis is conducted using the multi-phase compositional model CompFlow Bio, with the base scenario problem geometry reminiscent of a field experiment conducted by Rivett [Rivett, M.O., (1995), Soil–gas signatures from volatile chlorinated solvents: Borden field experiments. Groundwater, 33(1), 84–98.] at the Borden aquifer where groundwater was observed to transport a contaminant plume a substantial distance without vertical mass transport of the contaminant across the capillary fringe and into the vadose zone. Results for the base scenario model indicate that the structure of the permeability field was largely responsible for deflecting the groundwater plume upward towards the capillary fringe, permitting aqueous phase diffusion to transport the TCE into the vadose zone. Alternative permeability realizations, generated as part of a Monte Carlo simulation process, at times deflected the groundwater plume downwards causing the extended thickness of the saturated zone to insulate the vadose zone from exposure to the TCE by upward diffusive transport. Comparison of attenuation coefficients calculated using the CompFlow Bio and Johnson and Ettinger [Johnson, P.C. and Ettinger, R.A., (1991), Heuristic model for predicting the intrusion rate of contaminant vapors into buildings. Environmental Science and Technology, 25, 1445–1452.] heuristic model exhibited fortuitous agreement for the base scenario problem geometry, with this agreement diverging for the alternative permeability realizations as well as when parameters such as the foundation slab fracture aperture, the indoor air pressure drop, the capillary fringe thickness, and the infiltration rate were varied over typical ranges. 相似文献
643.
Incorporating layer- and local-scale heterogeneities in numerical simulation of unsaturated flow and tracer transport 总被引:1,自引:0,他引:1
Feng Pan Ming Ye Jianting Zhu Yu-Shu Wu Bill X. Hu Zhongbo Yu 《Journal of contaminant hydrology》2009,103(3-4):194-205
This study characterizes layer- and local-scale heterogeneities in hydraulic parameters (i.e., matrix permeability and porosity) and investigates the relative effect of layer- and local-scale heterogeneities on the uncertainty assessment of unsaturated flow and tracer transport in the unsaturated zone of Yucca Mountain, USA. The layer-scale heterogeneity is specific to hydrogeologic layers with layerwise properties, while the local-scale heterogeneity refers to the spatial variation of hydraulic properties within a layer. A Monte Carlo method is used to estimate mean, variance, and 5th, and 95th percentiles for the quantities of interest (e.g., matrix saturation and normalized cumulative mass arrival). Model simulations of unsaturated flow are evaluated by comparing the simulated and observed matrix saturations. Local-scale heterogeneity is examined by comparing the results of this study with those of the previous study that only considers layer-scale heterogeneity. We find that local-scale heterogeneity significantly increases predictive uncertainty in the percolation fluxes and tracer plumes, whereas the mean predictions are only slightly affected by the local-scale heterogeneity. The mean travel time of the conservative and reactive tracers to the water table in the early stage increases significantly due to the local-scale heterogeneity, while the influence of local-scale heterogeneity on travel time gradually decreases over time. Layer-scale heterogeneity is more important than local-scale heterogeneity for simulating overall tracer travel time, suggesting that it would be more cost-effective to reduce the layer-scale parameter uncertainty in order to reduce predictive uncertainty in tracer transport. 相似文献
644.
从某印染厂废水排放出口的污泥中分离到一株活性艳蓝X-BR染料高效降解菌LPY68-14,经生理生化鉴定,该菌为埃希氏菌(Escherichia sp.).研究了影响菌株LPY68-14降解效果的因素,实验结果表明:在缺氧、质量分数为0.2%葡萄糖为外加碳源、温度37℃、接种量4 mL、pH 7的最佳条件下,质量浓度为30 mg/L的活性艳蓝X-BR经菌株LPY68-14处理24 h后的降解率可达80%;当活性艳蓝X-BR质量浓度为100~400 mg/L时,该菌处理48 h后的降解率可稳定在70%左右. 相似文献
645.
646.
647.
Penggang Ren Tingting Shen Fang Wang Xing Wang Zhengwei Zhang 《Journal of Polymers and the Environment》2009,17(3):203-207
The thermoplastic starch (TPS) and nanocomposite(TPS/OMMT) was prepared with 15% carbamide, 15% ethanolamine and different
contents of organic activated montmorillonite (OMMT) by twin-screw extruder with a 130 °C barrel temperature. Fourier transforms
infrared spectroscopy and wide angle X-ray diffraction shown that the alkylamine in dodecyl benzyl dimethyl ammonium bromide
could react with MMT via cation exchange reaction. After treated, the d(001)space distance of MMT increased from 1.5 to 1.7 nm. Scanning electron microscope revealed that the lower contents of
OMMT could disperse well in the matrixes of TPS. The carbamide, ethanolamine and the OMMT could destroy the crystallization
behavior of starch, but only the OMMT restrained this behavior for long-term storing. Mechanical properties investigation
indicated that the tensile strength and modulus of TPS/OMMT nanocomposites were better than those of TPS, while the elongation
at break was descended with the increasing of OMMT contents. When the content of OMMT was 4%, the tensile strength and modulus
of TPS was improved from 4.2 and 42 MPa to 6.0 and 76 MPa, respectively. 相似文献
648.
Fu-Sheng Liu Zhuo Li Shi-Tao Yu Xiao Cui Cong-Xia Xie Xiao-Ping Ge 《Journal of Polymers and the Environment》2009,17(3):208-211
Alkali-catalyzed methanolysis and hydrolysis of polycarbonate (PC) in a solvent in which PC can substantially dissolve such
as N-methyl-2-pyrrolidone, 1,4-dioxane, tetrahydrofuran and so on were studied. Reaction conditions were optimized for the purpose
of recycling PC in the form of bisphenol A and carbon carbonate. The results showed that both the methanolysis and hydrolysis
of PC could take place under moderate conditions. Under the conditions of reaction temperature 40 °C, m(PC):m(MeOH) = 1:1,
m(PC):m(NaOH) = 50:1, reaction time 35 min and using tetrahydrofuran as solvent, the methanolysis conversion of PC was almost
100% and the yield of bisphenol A was over 95%. Moreover, under the conditions of reaction temperature 100 °C, m(PC):m(H2O) = 1:0.7, m(PC):m(NaOH) = 10:1, reaction time 8 h and using 1,4-dioxane as solvent, the hydrolysis conversion of PC was
almost 100% and the yield of bisphenol A was over 94%. 相似文献
649.
Shinya Inazumi Hiroyasu Ohtsu Yu Otake Makoto Kimura Masashi Kamon 《Journal of Material Cycles and Waste Management》2009,11(1):55-64
An evaluation method that can express the local leakage of leachate from joint sections in steel pipe sheet pile (SPSP) cutoff
walls is discussed in this study. In particular, the evaluation of environmental feasibility (containment of leachates containing
toxic substances) considering a three-dimensional arrangement and hydraulic conductivity distribution of the joint sections
in the SPSP cutoff wall is compared with an evaluation that uses the equivalent hydraulic conductivity. This equivalent hydraulic
conductivity assumes that the joint section and the steel pipe are integrated; therefore, the hydraulic conductivity is substituted
with a uniform permeable layer. However, in an evaluation that employs the equivalent hydraulic conductivity, it is difficult
to consider the local leakage of leachate containing toxic substances from the joint sections in the SPSP cutoff wall. It
was established that evaluations of the environmental feasibility of SPSP cutoff walls with joint sections must take into
account the local leakage of leachates containing toxic substances from the joint sections. Also, it was clarified that technologies
that lower the hydraulic conductivities of joint sections in SPSP cutoff walls and also facilitate the use of sparser joint
arrangements contribute significantly to increasing the environmental feasibility of SPSP cutoff walls at landfill sites. 相似文献
650.