Degradation of MTBE and TBA by a new isolate from MTBE-contaminated soil

Methyl ten-butyl ether （MTBE）, a gasoline additive, possesses serious problems to the environmental health. In the present study, a bacterial culture named A-3 which could effectively degrade MTBE was isolated from the MTBE contaminated soil. The isolate was identified as Chryseobacterium sp., a new species capable of degrading MTBE. In order to enhance its degradation ability, selected environment factors were investigated. The results showed that the optimal temperature was in the range of 25-30℃, the pH was 7.0, the inoculum size was 2 × 10^8 CFU/ml and the optimal concentration of MTBE was from 50 to 100 mg/L. The maximum MTBE utilization rate （Vmax） was 102 nmol MTBE/（mg cell protein.h）. Furthermore, it was found that the isolate could also degrade tert-butyl alcohol （TBA）. The degradation rates of TBA were much faster than those of MTBE. The additional TBA would lead to the decrease of the initial MTBE degradation rate and the inhibitory effect of TBA increased with the increase of TBA concentration. Similar protein profiles at least seven peptides were demonstrated after SDS-PAGE analysis of crude extracts obtained from the cells growing in MTBE and TBA culture.     

Effect of Sb dopant amount on the structure and electrocatalytic capability of Ti/Sb-SnO2 electrodes in the oxidation of 4-chlorophenol

Ti/Sb-SnO_2 anodes were prepared by thermal decomposition to examine the influence',of the amount of Sb dopant on the structure and electrocatalytic capability of the electrodes in the oxidation of 4-chlorophenol.The physicochemical properties of the Sb-SnO_2 coating were markedly influenced by different amounts of Sb dopant.The electrodes,which contained 5% Sb dopant in the coating, presented a much more homogenous surface and much smaller mud-cracks,compared with Ti/Sb-SnO_2 electrodes containing 10% or 15% Sb dopant,which exibited larger mud cracks and pores on the surface.However,the main microstructure remained unchanged with the addition of the Sb dopant.No new crystal phase was observed by X-ray diffraction(XRD).The electrochemical oxidation of 4-chlorophenol on the Ti/SnO_2 electrode with 5% Sb dopant was inclined to electrochemical combustion;while for those containing more Sb dopant,intermediate species were accumulated.The electrodes with 5% Sb dopant showed the highest efficiency in the bulk electrolysis of 4-chlorophenol at a current density of 20 mA/cm~2 for 180 min;and the removal rates of 4-chlorophenol and COD were 51.0% and 48.9%,respectively.     

Di（2-ethylhexyl）phosphoric acid-coconut oil supported liquid membrane for the separation of copper ions from copper plating wastewater

Permeation of Cu(II) from its aqueous solution through a supported liquid membrane (SLM) containing di(2-ethylhexyl)phosphoric acid (D2EHPA) carrier dissolved in coconut oil has been studied. The effects of Cu(II), pH (in feed), H2SO4 (stripping) and D2EHPA (in membrane) concentrations have been investigated. The stability of the D2EHPA-coconutoil has also been evaluated. High Cu(II) concentration in the feed leads to an increase in flux from 4.1 × 10-9 to 8.9 × 10-9 mol/(m2·s) within the Cu(II) concentration range 7.8×10-4-78.6×10-4 mol/L at pH of 4.0 in the feed and 12.4 × 10-4 mol/L D2EHPA in the membrane phase. Increase in H2SO4 concentration in strip solution leads to an increase in copper ions flux up to 0.25 mol/L H2SO4, providing a maximum flux of 7.4 × 10-9 mol/(m2·s). The optimum conditions for Cu(II) transport are, pH of feed 4.0, 0.25 mol/L H2SO4 in strip phase and 12.4 × 10-4 mol/L D2EHPA (membrane) in 0.5 (m pore size polytetrafluoroethylene (PTFE) membrane. It has been observed that Cu(II) flux across the membrane tends to increase with the concentration of copper ions. Application of the method developed to copper plating bath rinse solutions has been found to be successful in the recovery of Cu(II). rane. It     

Removal of carotene-like colored compounds by liquid-liquid extraction during polycyclic aromatic hydrocarbons analysis of plant tissue

Plants contain a wide variety of chemicals, some of which may have similar chromatographic behavior to polycyclic aromatic hydrocarbons (PAHs). During solid phase extraction (SPE) with Si-gel for instance, the co-elution of carotene-like colored compounds with PAHs has been observed. In this paper, liquid–liquid extraction was applied for the separation and subsequent analysis of PAHs from plant extracts. PAHs containing 2–6 rings, which include naphthalene, phenanthrene, pyrene, benzo[a]pyrene and benzo[ghi]perylene, were used as representative target chemicals. Carotene-like compounds extracted from Komatsuna (Brassica campestris) shoot by acetone followed by Si-gel treatment were incorporated as undesired components in the model matrix. Results showed the feasibility of employing either acetonitrile or 2% (w/v) KOH–methanol as solvents for high PAHs recovery and low extraction of colored fraction. For acetonitrile, 86.9–93.5% of each PAH could be recovered after three extraction cycles (relative standard deviation, RSD < 1.6%) with only about 10% co-extraction of colored fraction. For 2% KOH–methanol, PAHs recoveries ranging from 79.3% to 83.1% after five cycles (RSD < 1.5%) were achieved while the percent extraction of colored fraction was also low at 10%. The relatively higher selectivity of the solvents for PAHs over the colored fraction as well as the solubility of the matrix solution in the solvent may have contributed to these results. On this basis, liquid–liquid extraction is very useful for the pre-treatment of plant extracts for PAHs analysis.     

Biodegradation of mono-alkyl phthalate esters in natural sediments

Mono-alkyl phthalate esters (MPEs) are primary metabolites of di-alkyl phthalate esters (DPEs), a family of industrial chemicals widely used in the production of soft polyvinyl chloride and a large range of other products. To better understand the long term fate of DPEs in the environment, we measured the biodegradation kinetics of eight MPEs (-ethyl, -n-butyl, -benzyl, -i-hexyl, -2-ethyl-hexyl, -n-octyl, -i-nonyl, and -i-decyl monoesters) in marine and freshwater sediments collected from three locations in the Greater Vancouver area. After a lag period in which no apparent biodegradation occurred, all MPEs tested showed degradation rates in both marine and freshwater sediments at 22 °C with half-lives ranging between 16 and 39 h. Half-lives increased approximately 8-fold in incubations performed at 5 °C. Biodegradation rates did not differ between marine and freshwater sediments. Half-lives did not show a relationship with increasing alkyl chain length. We conclude that MPEs can be quickly degraded in natural sediments and that the similarity in MPE degradation kinetics among sediment types suggests a wide occurrence of nonspecific esterases in microorganisms from various locations, as has been reported previously.     

Book Reviews

Books reviewed:
Rutherford H., Platt et al. Disasters and Democracy: The Politics of Extreme Natural Events
S., Suri Orissa Disaster: Agony of the Living     

The Accuracy of Mortality Reporting in Displaced Persons Camps During the Post-emergency Phase

For humanitarian organisations, accurate data are essential to identify emerging health problems and determine programme needs. We visited 45 post-emergency phase displaced persons camps and collected three months' mortality data which we compared with organisations' routine mortality reports. Organisations reported 612 deaths and we identified 741 deaths, for a mortality-reporting ratio, defined as the number of organisation-reported deaths divided by the number of investigator-identified deaths, of 83 per cent. For the majority of camps which under-reported deaths, mortality reporting ratios were significantly higher for women than men, and for camps with central mortality registers rather than those without. In the few camps which over-reported deaths, these occurred primarily among children younger than five years of age, probably due to the inclusion of abortions and stillbirths. Despite the overall under-reporting of deaths by humanitarian organisations, the existing health information systems appear to estimate mortality rates adequately in these post-emergency camps. However, organisations should improve the precision and completeness with which they report the characteristics of deaths in order to provide valuable data to target their programmes at the most vulnerable people.     

Analysis of a gas-phase partitioning tracer test conducted in an unsaturated fractured-clay formation

The gas-phase partitioning tracer method was used to estimate non-aqueous phase liquid (NAPL), water, and air saturations in the vadose zone at a chlorinated-solvent contaminated field site in Tucson, AZ. The tracer test was conducted in a fractured-clay system that is the confining layer for the underlying regional aquifer. Three suites of three tracers were injected into wells located 14, 24, and 24 m from a single, central extraction well. The tracers comprised noble gases (traditionally thought to be nonsorbing), alkanes (primarily water partitioning), perfluorides (primarily NAPL partitioning), and halons (both NAPL and water partitioning). Observations of vacuum response were consistent with flow in a fractured system. The halon tracers exhibited the greatest amount of retardation, and helium and the perfluoride tracers the least. The alkane tracers were unexpectedly more retarded than the perfluoride tracers, indicating low NAPL saturations and high water saturations. An NAPL saturation of 0.01, water saturation of 0.215, and gas saturation of 0.775 was estimated based on analysis of the suite of tracers comprising helium, perfluoromethylcyclohexane and dibromodifluoromethane, which was considered to be the most robust set. The estimated saturations compare reasonably well to independently determined values.     

固相微萃取-气相色谱法测定水中痕量有机氯农药

建立了固相微萃取-气相色谱联用快速测定水中14种痕量有机氯农药的方法,对比研究了浸入式直接固相微萃取与顶空固相微萃取两种方式对不同有机氯农药的富集效率,优化了试验条件.方法线性关系良好,检出限为0.1 ng/L～10 ng/L,定量下限为0.2 ng/L～40 ng/L,RSD＜8%,实际水样的加标回收率为67.0%～133%.     

水中微量弱极性内分泌干扰物测定方法的研究

使用ENVITM Chrom P固相萃取小柱、双(三甲基硅烷基)三氟乙酰胺(BSTFA)衍生剂及气质联机,系统研究了水中弱极性内分泌干扰物(EDCs)的测定方法.通过正交试验,得到最佳固相萃取条件为:水样流速5 mL/min,洗脱剂为二氯甲烷,洗脱速率0.5 mL/min,洗脱剂体积6 mL.最佳衍生化条件为:BSTFA 100 μL,60 ℃,反应时间30 min.结果表明,双酚A、五氯酚、2,4-二氯苯酚、4-壬基酚、雌二醇、雌三醇、雌酮、炔雌二醇的回收率在82.4%～101.9%,检出限为0.01～0.06 μg/L.