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1.
Microbial consortia isolated from aged oil-contaminated soil were used to degrade 16 polycyclic aromatic hydrocarbons (15.72 mgkg(-1)) in soil and slurry phases. The three microbial consortia (bacteria, fungi and bacteria-fungi complex) could degrade polycyclic aromatic hydrocarbons (PAHs), and the highest PAH removals were found in soil and slurry inoculated with fungi (50.1% and 55.4%, respectively). PAHs biodegradation in slurry was lower than in soil for bacteria and bacteria-fungi complex inoculation treatments. Degradation of three- to five-ring PAHs treated by consortia was observed in soil and slurry, and the highest degradation of individual PAHs (anthracene, fluoranthene, and benz(a)anthracene) appeared in soil (45.9-75.5%, 62-83.7% and 64.5-84.5%, respectively) and slurry (46.0-75.8%, 50.2-86.1% and 54.3-85.7%, respectively). Therefore, inoculation of microbial consortia (bacteria, fungi and bacteria-fungi complex) isolated from in situ contaminated soil to degrade PAHs could be considered as a successful method.  相似文献   

2.
The biodegradation of 16 USEPA-listed PAHs (SigmaPAHs) during simulated in-vessel composting-bioremediation of an aged coal-tar-contaminated soil amended with fresh green waste compost (FGWC) collected from two landfill sites in the United Kingdom (UK) were studied over 56 days. The experimental design compared three constant temperature profiles (TC=38, 55 and 70 degrees C) with one variable temperature profile including treatment at 70 degrees C to comply with regulatory requirements (TP1). The highest disappearance of SigmaPAHs was observed in the soil amended with FGWC (53.2% and 48.1% SigmaPAHs disappearance in soil amended with FGWC-Site 1 and FGWC-Site 2, respectively) containing lower initial organic mater (TOM) (Initial TOM(FGWC-Site 1)=25.6+/-0.6%相似文献   

3.
The phenomenon of contaminant sequestration—and the physicochemical soil parameters which drive this process—has recently been studied by several authors with regard to microbial contaminant degradation. Very little work has been done to determine the effects of contaminant sequestration on the chemical treatability (oxidizability) of soil contaminants; the current study was conducted to address this data gap. A suite of six model soils, ranging in organic matter content from 2.32 to 24.28%, were extensively characterized. Measured parameters included: (1) levels of total organic carbon (TOC); (2) contents of humic acid (HA); fulvic acid (FA) and humin; and (3) total porosity and surface area. Each soil was then spiked with coal tar and, after varying periods of aging/sequestration, subjected to slurry-phase Fenton’s reagent oxidation. Percent recoveries of 12 PAHs, ranging from 3 to 6 aromatic rings, were determined. Results indicated that the susceptibility of each PAH to chemical oxidation was a function of TOC in four of the soils (those with TOC greater than approximately 5%), but was strongly dependent on soil porosity for low-TOC soils. The importance of these two parameters changed with increasing sequestration time, with the relative contribution of porosity-mediated sequestration becoming more important over time. Porosity-mediated effects were more rapid and significant with lower-molecular-weight PAHs (e.g. those with three or four aromatic rings) than with higher-molecular-weight, more hydrophobic compounds. These observations are discussed in light of current physicochemical models of the contaminant sequestration process.  相似文献   

4.
5.
Accumulation of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) by crop plants from contaminated soils may pose health risks. A greenhouse pot experiment using lettuce (Lactuca satuva L.) as a representative vegetable was conducted to assess the concentrations of PAHs and HMs in vegetables grown in wastewater-contaminated soils. The concentrations of total PAHs were ranged from 1.5 to 3.4 mg kg(-1) in the contaminated soils, while 1.2 mg kg(-1) in the reference soil. Linear regression analyses showed that the relationships between soil and shoot PAH concentrations were stronger for LMW-PAHs (R(2) between 0.51 and 0.92) than for HMW-PAHs (R(2) 0.02 and 0.60), suggesting that translocation for LMW-PAHs is faster than HMW-PAHs. Furthermore, the data imply that root uptake was the main pathway for HMW-PAHs accumulation. The plant shoots were also highly contaminated with HMs, particularly Cd (0.4-0.9 mg kg(-1)), Cr (3.4-4.1 mg kg(-1)), Ni (11.7-15.1 mg kg(-1)) and Pb (2.3-5.3 mg kg(-1)), and exceed the guidance limits set by State Environmental Protection Administration (SEPA), China and the World Health Organization (WHO). This study highlights the potential health risks associated with cultivation and consumption of leafy vegetables on wastewater-contaminated soils.  相似文献   

6.
2002年4月厦门港沿岸设九个站,员当湖设两个站采集表层积物,用有机溶剂萃取,硅胶柱色层分离,气相色谱-质谱联机带SIM数据采集系统对样品的石油烃类(M/Z=55),多环芳香烃类(15个典型的多环芳香烃,9个甲基化多环芳香烃作外标)进行分析,结果显示员当湖石油烃和多环芳香浓度分别高达1397微克/克(干)和1376.5纳克/克(干)。厦门港沉积物石油烃和多环芳香浓度范围为:石油烃133.3~943.3微克/克(干)多环芳香烃97.6~308.5纳克/克(干)。厦门港船只活动,厦门港四周工业废水、车辆燃油滴漏是石油烃污染的主要来源。厦门工业用煤、用油、生活用煤及船只、车辆燃料泄漏是沉积物多环芳香烃的主要来源,其工业排废、生活废水排放,市区雨水冲刷和大气灰尘沉降是多环芳香烃进入海湾的主要途径。  相似文献   

7.
Ambient air and dry deposition samples were collected at suburban and urban sites in Izmir, Turkey. Atmospheric total (particle+gas) ∑(14)PAHs concentrations were 36±39 and 144±163 ng m(-3) for suburban and urban sites, respectively. Phenanthrene was the most abundant compound at all sites, and all samples were dominated by low molecular weight PAHs. Average particulate ∑(14)PAH dry deposition fluxes were 8160±5024 and 4286±2782 ng m(-2) day(-1) and overall average particulate dry deposition velocities were 1.5±2.4 and 1.0±2.3 cm s(-1) for suburban and urban sites, respectively. Soil samples were collected at suburban site. Average soil concentration for ∑(14)PAH was 55.9±14.4 ng g(-1) dry weight. Calculated gas-phase air-soil exchange fluxes indicated that fluorene, phenanthrene, anthracene, and carbazole were deposited to soil in winter while they were volatilized in summer. Other compounds (fluoranthene-benzo[g,h,i]perylene) were deposited to soil in both periods. Annual average fluxes of PAHs representing soil to air (i.e., gas volatilization) and air to soil transfer (i.e., gas absorption, dry deposition, and wet deposition) processes were also compared. All processes were comparable for Σ(14)PAHs however their input was dominated by gas absorption. Gas absorption dominated for lower molecular weight PAHs, however dry deposition dominated for higher molecular weight PAHs. The results have suggested that for fluorene, soil and air may be approaching a steady state condition. For the remaining compounds, there was a net accumulation into the soil.  相似文献   

8.
Isola delle Femmine Natural Reserve is a very little isle about 15 km from the centre of Palermo, in front of a plant for the production of cement and about 600 m from coast. In the present research, profiles soil PAHs were obtained for 16 sites within the reserve and for 8 stations on the rural soil taken as reference. ∑PAHs, in the soil of investigated area, ranged from 35 to 545 μg/kg. With the aim to find the origin of PAHs in the soil of Isola delle Femmine, we compare the distribution of single analytes in the investigated area with those of the reference rural area (Monte Raffo Rosso), with those of atmospheric urban particulate collected at Palermo along with reported of emissions of some cement plants. The island's investigated area showed a high amount of 4- and 5-rings PAHs, whereas 3-ring PAHs are present mainly in the emission of cement plants (from literature). The percentage of 3-, 4-, 5- and 6-rings PAHs determined in samples of Isola delle Femmine are similar to those of the reference rural soils and to those of urban atmospheric particulate. Cement plant activity has a negligible weight on the presence of PAHs in the soil of Isola delle Femmine.  相似文献   

9.
Sixteen priority polycyclic aromatic (PAHs) in PM(2.5) and PM(2.5-10) samples collected from 20 sites in Beijing, China in December 2005 and January 2006 were analyzed to determine the composition, spatial distribution and sources. Total PAHs of PM(2.5) and PM(2.5-10) ranged from 5.2 to 1062.2 ng m(-3) and 7.6 to 759.7 ng m(-3), respectively, categorized as heavier pollution. Among five kind of functional zones involved, industrial center, commercial area and village were heavily polluted. The mean concentration of PAHs in PM(2.5) of 407 ng m(-3) was 1.67-fold of that in PM(2.5-10), which was relatively high compared to the previous studies (winter in 2001 and 2002). The most evident change was the increase of Flu, BbkF and InP, which are believed to be less harmful and related to the increasing use of clean energy. However, pollution distribution was spatially heterogeneous inside the city. The most polluted sites located in the southeast of the city. Unlike previous studies, fluoranthene was the most abundant component quantified, which could be associated with increasing use of natural gas as clean energy. Compositional analysis and principal component analysis (PCA) suggested that different kinds of combustion were the main source of the PAHs in PM, though contribution of coal was still evident.  相似文献   

10.
The contamination of sediments and mussels sampled from Abu Qir Bay by polycyclic aromatic hydrocarbons (PAHs) was investigated. Concentrations of PAHs recorded in the bay sediments ranged from <MDL to 2660 μg/kg dw. In general, concentrations of PAHs in mussels were higher than their corresponding sediment concentrations reflecting their great bioavailability (242–3880 μg/kg dw). The highest concentration was observed in the western part of the bay, a location affected by intensive shipping activities. The distribution pattern of PAHs was similar for mussels and sediments, particularly for sediments characterized by high contamination level, and they were dominated by the high molecular weight PAHs (4–6-rings). Applying different PAHs ratios, it was found that PAHs originated predominantly from the pyrogenic source either from the combustion of grass, wood and coal (majority of the samples) or from petroleum combustion (harbour area). The output of a Screening Level Ecological Risk Assessment (SLERA) on the bay sediments revealed that adverse ecological effects to benthic organisms are expected to occur in only one sample, and thus PAHs are not considered as contaminants of concern in Abu Qir Bay. Also adverse health effects are not expected to occur from the consumption of the investigated mussels with respect to PAHs in Abu Qir Bay.  相似文献   

11.
To enhance the catalytic oxidation of pentachlorophenol (PCP) in contaminated soil suspensions using tetra(p-sulfophenyl)porphineiron(III) (Fe(III)-TPPS) as a catalyst and potassium monopersulfate (KHSO(5)) as the single-oxygen donor, the effect of added hydroxypropyl-beta-cyclodextrin (HP-beta-CD) was examined. At pH 4 and 6, the percentage of PCP disappearance increased substantially in the presence of HP-beta-CD. In addition, the self-degradation of Fe(III)-TPPS was significantly retarded in the presence of HP-beta-CD. This retarded self-degradation can be attributed to the stabilization of Fe(III)-TPPS via the formation of a supramolecular complex with HP-beta-CD. The kinetic constant for the self-degradation of Fe(III)-TPPS in the presence of HP-beta-CD at pH 6 was much smaller than that at pH 4, indicating that Fe(III)-TPPS is more stable at pH 6. Thus, the amount of Fe(III)-TPPS, KHSO(5) and HP-beta-CD required to degrade PCP in contaminated soil suspensions was optimal at pH 6. When PCP-contaminated soil suspensions were treated under the optimized conditions, 12-18% and 24-28% of the PCP was mineralized to CO(2) in the absence and presence of HP-beta-CD, respectively. These results show that the presence of HP-beta-CD in the Fe(III)-TPPS/KHSO(5) catalytic system is effective in enhancing the degradation of PCP in contaminated soil suspensions.  相似文献   

12.
High shear wet granulation (HSWG), as a widely used granulation technology, has been studied extensively. However, for the HSWG of formulations containing hydrophobic components, the influence of process variables on the properties of granules and tablets has not been reported. In the present study, based on a combination of quality by design and multivariate analysis (MVA) approaches, quercetin with high-dose and high-hydrophobicity was used to study the relationship between process variables, granule properties, and tablet properties in HSWG systematically. Control and response variables were determined using risk assessment. The optimal fitting empirical models established by Box-Behnken design showed that the liquid to solid ratio and impeller speed were the most important factors, which affected all product properties except Carr’s index and yield pressure. Instead, the influence of wet massing time was relatively small (only the effects on yield, granule size, granule hardness, and compression ratio were significant). Then, the process design space was obtained by limiting the related critical quality attributes, which was verified effectively. Scanning electron microscope images showed that smooth granules were produced using higher process parameters, whereas rough and porous granules resulted at lower process parameters. Furthermore, the MVA results demonstrated that increasing the granule hardness led to an increase in the compression ratio and a decrease in tensile strength of the tablets. Tablet fragility and disintegration time were mainly affected by granule density and bulk density, respectively, and both were negatively correlated. The established research paradigm is not only conducive to the successful development of quercetin products, but also provides valuable guidance for improving HSWG–based product development with such formulation characteristics.  相似文献   

13.
Some farmland in Shenyang had been irrigated with industrial wastewater since 1962. Although wastewater irrigation was ceased in 1992, soil had been heavily polluted by heavy metals, especially by Cd. For better understanding processes of soil-heavy metal interactions, in particular, the mobility and retention mechanism of heavy metal in soil, a study on the transport and fate of heavy metals in soil zones from Shenyang suburb was carried out by column leaching tests in laboratory. Breakthrough curves of Pb, Cd, Cr(VI) and As(V) fitted by Thomas model and Yoon–Nelson model. The results of fitted breakthrough curves showed that transport rates of the four heavy metals in the soil zones followed the order: Cr(VI) > As(V) > Cd > Pb, which indicated that Cr(VI) was much more mobile, and Pb was comparatively unmovable. Cr in effluents and As were almost entirely Cr(VI) and As(V), respectively, and no Cr(III) and As(III) was ever detected during the leaching tests. The contents of Pb, Cd, Cr and As in leached soils decreased in the order of Pb > Cd > Cr > As, which suggested that adsorption ability of soil to Pb was greatest and to As was least. The methods of selective sequential extraction and solvent extraction were used to determine the fractions of Pb, Cd, Cr, As and the valent states of Cr, As [Cr(VI) or Cr(III), As(V) or As(III)] in original soils and in leached soils. After leaching tests, the relative and absolute concentrations of exchangeable, carbonate, Fe–Mn oxide and organic fraction of each element were all increased, which enhanced the potential mobility and risk of Pb, Cd, Cr and As to soil/groundwater system. The relative concentrations of Cr(III) and As(III) in different depth of the soil zones after leaching tests were increased by about 6.0% and 5.6%, respectively. Cr(III) and As(III) tended to be adsorbed by soils, which reduced the mobility of them into groundwater.  相似文献   

14.
李晨旭  彭伟  方振东  刘杰 《材料导报》2018,32(13):2223-2229
近年来,水体中富集的难降解污染物导致了诸多环境问题,传统水处理工艺并不能对其进行有效处理。高级氧化技术是目前处理难降解污染物的最有效方法。过渡金属氧化物非均相催化过硫酸氢盐(PMS)活化生成硫酸根自由基(SO_4~-·)处理水体中难降解污染物是近些年新兴的高级氧化技术,与以生成羟基自由基(·OH)为基础的传统高级氧化技术相比,该技术具有对pH适应范围更宽、中性条件下氧化性更强、自由基半衰期更长的优势,同时也克服了均相催化体系中金属离子的二次污染、难以重复利用的问题,受到环境领域学者的广泛关注,为去除水体中抗生素、激素等难降解污染物提供了新的思路和方法。然而,由于活性点位的减少,相较于均相催化,非均相催化的催化效率更低,同时也存在催化稳定性差、难以回收等不足。针对上述问题,近几年除了探寻对PMS的活化具有催化活性的新型过渡金属氧化物外,研究者主要从催化材料的负载、改性以及复合三方面进行尝试,并取得了丰富的研究成果,在发挥非均相催化经济、环保优势的同时,大幅提高了催化剂的催化效率及可回收性,为其步入实际应用做出了巨大的贡献。在众多过渡金属元素中,钴、铁、锰的氧化物已被证明对PMS的活化具有催化活性并得到了广泛的研究。其中,由于钴离子对PMS表现出最强的活化能力,因此对钴系氧化物研究得最早。随后,铁及锰的氧化物因环境友好、廉价易得的优势逐渐成为钴氧化物的替代品。近五年的研究工作将纳米碳、介孔材料以及金属-有机框架等引入催化剂的制备合成中,对过渡金属氧化物进行负载和改性,加强了催化材料的电子传递速度和化学稳定性,为解决催化剂的催化效率低与催化稳定性差等问题提供了有效方法。此外,以两种过渡金属元素为催化核心的二元复合材料,在降低催化剂制作成本的同时,还可以实现催化剂效能和稳定性的双重提高。文章介绍了钴系氧化物、锰系氧化物、铁系氧化物等三种能够催化PMS活化的一元非均相催化剂的研究进展,并阐述了二元复合催化剂的研究现状,总结了现阶段研究的不足并对未来的发展方向做出了展望,以期为制备经济高效的过渡金属氧化物催化剂提供参考。  相似文献   

15.
16.
A comparative study on atmospheric polycyclic aromatic hydrocarbons (PAHs) in particulate matter and the gaseous phase was performed at an urban and a residential site in Osaka, Japan, during 2005-2006. PAH concentrations at the urban site were found to be approximately twice higher than those at the residential site. At both sites, particulate PAH concentrations increased mainly in winter while the trends of temporal change in gaseous PAH concentrations were not clearly observed. The main sources of PAHs were estimated to be local traffic, e.g., diesel engines with catalytic converter. PAH concentrations did not significantly negatively correlate with ozone concentrations and meteorological parameters. Gas-particle partitioning coefficients of representative PAHs with low molecular weight (LMW) significantly negatively correlated with ambient temperature, showing that temporal change in the LMW PAH concentrations in PM could be attributable to the shift of their gas-particle distribution caused by the change in ambient temperature. For the first time, we studied the effect of the formation of atmospherically stable layer following an increase in PAH concentrations in Japan. At the urban site, PAHs showed a significant positive correlation with potential temperature gradients, indicating that temporal variability in PAH concentrations would be dominantly controlled by the formation of atmospherically stable layer in Osaka area.  相似文献   

17.
The X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and CO titration has been used to detect common impurities like carbon and sulphur on Pd(111) and Pt(111) surfaces. Different experimental problems are discussed and practical tips for the cleaning of Pd(111) and Pt(111) are given. A mechanism for the carbon oxidation on closed packed platinum group metals like Pt(111) and Pd(111) is presented. The bulk carbon concentration of Pd(111) was estimated based on the Langmuir-McLean theorem. Additionally it was shown that the titration with CO and subsequent XPS measurement is a powerful yet convenient method for quantitative detection of impurities and ceria coverage determination. A CeOx/Pd(111) inverse model system was prepared by evaporation of cerium in an oxygen atmosphere. The comparative study has shown that sulphur contamination changes the redox properties of the CeOx in the CeOx/Pd(111) system.  相似文献   

18.
A new binary Co1/2Fe1/2(H2PO4)2·2H2O was synthesized by a simple, rapid and cost-effective method using CoCO3-Fe(c)-H3PO4 system at ambient temperature. Thermal treatment of the obtained Co1/2Fe1/2(H2PO4)2·2H2O at 600 °C yielded as a binary cobalt iron cyclotetraphosphate CoFeP4O12. The FTIR and XRD results of the synthesized Co1/2Fe1/2(H2PO4)2·2H2O and its final decomposed product CoFeP4O12 indicate the monoclinic phases with space group P21/n and C2/c, respectively. The particle morphologies of both binary metal compounds appear the flower-like microparticle shapes. Room temperature magnetization results show novel superparamagnetic behaviors of the Co1/2Fe1/2(H2PO4)2·2H2O and its final decomposed product CoFeP4O12, having no hysteresis loops in the range of ±10,000 Oe with the specific magnetization values of 0.045 and 12.502 emu/g at 10 kOe, respectively. The dominant physical properties of the obtained binary metal compounds (Co1/2Fe1/2(H2PO4)2·2H2O and CoFeP4O12) are compared with the single compounds (M(H2PO4)2·2H2O and M2P4O12; where M = Co, Fe), indicating the presence of Co ions in substitution position of Fe ions.  相似文献   

19.
In this paper we report further work on the perovskite oxide carbonate, Ba4ScCu2O7−x(CO3)y (x≈0.3, y≈0.9). The X-ray diffraction pattern for this phase can be indexed on a 2ap×2ap×cp cell (where ap, cp are the primitive perovskite cell lengths). On heating this phase to higher temperature, partial loss of CO32− occurs and the pattern now can be indexed on a √2ap×√2ap×2cp cell, similar to that previously observed for the system Ba4YCu2+xO6+y(CO3)z. Structural studies using powder neutron diffraction show that Ba4ScCu2O7−x(CO3)y (x≈0.3, y≈0.9) exhibits a new example of ordering within the small cation sites, with an ordered arrangement of Sc, Cu and C (from the carbonate group). It appears, however, from the refined data that this ordering may not be complete, which can probably be explained by the presence of small regions of the low carbonate content phase. Discussion of the factors influencing the relative stabilities of the high and low carbonate content phases is also presented.  相似文献   

20.
In this paper, we report a simple and sensitive on-line solid phase extraction system for the preconcentration and determination of Cu(II) by flame atomic absorption spectrometry (FAAS). This method is based upon the on-line retention of copper at pH 5.0 on a minicolumn packed with chloromethylated polystyrene modified by 1-phenyl-1,2-propanedione-2-oxime thiosemicarbazone (PPDOT) as a new solid-phase extraction (SPE) sorbent. The retained Cu(II) ions were eluted with 1.0 M HNO3, and transported directly to FAAS for determination. Several chemical and flow variables were studied and optimized for a quantitative preconcentration and determination of copper(II). At the optimized conditions, for preconcentration of 10.0 mL of a sample solution, a linear calibration graph was obtained over the concentration range of 3.00-120.0 μg L−1 for Cu(II). The limit of detection (3σ), limit of quantification (10σ), and enrichment factor are 0.56 μg L−1, 2.0 μg L−1 and 41, respectively. The relative standard deviation (n = 6) at 20 μg L−1 of Cu(II) is 2.0%. This method could be applied for determination of trace amounts of Cu(II) in water, soil, and food samples with satisfactory results.  相似文献   

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