Cement-fly ash stabilisation/solidification of contaminated soil: Performance properties and initiation of operating envelopes

This study was aimed at evaluating the mechanical and pH-dependent leaching performance of a mixed contaminated soil treated with a mixture of Portland cement (CEMI) and pulverised fuel ash (PFA). It also sought to develop operating envelopes, which define the range(s) of operating variables that result in acceptable performance. A real site soil with low contaminant concentrations, spiked with 3000mg/kg each of Cd, Cu, Pb, Ni and Zn, and 10,000mg/kg of diesel, was treated with one part CEMI and four parts PFA (CEMI:PFA=1:4) using different binder and water contents. The performance was assessed over time using unconfined compressive strength (UCS), hydraulic conductivity, acid neutralisation capacity (ANC) and pH-dependent leachability of contaminants. With binder dosages ranging from 5% to 20% and water contents ranging from 14% to 21% dry weight, the 28-day UCS was up to 500kPa and hydraulic conductivity was around 10-8m/s. With leachant pH extremes of 7.2 and 0.85, leachability of the contaminants was in the range: 0.02-3500mg/kg for Cd, 0.35-1550mg/kg for Cu, 0.03-92mg/kg for Pb, 0.01-3300mg/kg for Ni, 0.02-4010mg/kg for Zn, and 7-4884mg/kg for total petroleum hydrocarbons (TPHs), over time. Design charts were produced from the results of the study, which show the water and/or binder proportions that could be used to achieve relevant performance criteria. The charts would be useful for the scale-up and design of stabilisation/solidification (S/S) treatment of similar soil types impacted with the same types of contaminants. © 2013 Elsevier Ltd.

Investigation of the dilution process for measurement of particulate matter from spark-ignition engines

Measurements of particulate matter (PM) from spark ignition (SI) engine exhaust using dilution tunnels will become more prevalent as emission standards are tightened. Hence, a study of the dilution process was undertaken in order to understand how various dilution related parameters affect the accuracy with which PM sizes and concentrations can be determined. A SI and a compression ignition (CI) engine were separately used to examine parameters of the dilution process; the present work discusses the results in the context of SI exhaust dilution. A Scanning Mobility Particle Sizer (SMPS) was used to measure the size distribution, number density, and volume fraction of PM. Temperature measurements in the exhaust pipe and dilution tunnel reveal the degree of mixing between exhaust and dilution air, the effect of flowrate on heat transfer from undiluted and diluted exhaust to the environment, and the minimum permissible dilution ratio for a maximum sample temperature of 52°C. Measurements of PM concentrations as a function of dilution ratio show the competing effects of temperature and particle/vapor concentrations on particle growth dynamics, which result in a range of dilution ratios-from 13 to 18-where the effect of dilution ratio, independent of flowrate, is kept to a minimum. This range of dilution ratios is therefore optimal in order to achieve repeatable PM concentration measurements. Particle dynamics during transit through the tunnel operating at the optimal dilution ratio was found statistically insignificant compared to data scatter. Such small differences in number concentration may be qualitatively representative of particle losses for SI exhaust, but small increases in PM volume fraction during transit through the tunnel may significantly underestimate accretion of mass due to unburned hydrocarbons (HCs) emitted by SI engines. The fraction of SI-derived PM mass due to adsorbed/absorbed vapor, estimated from these data, is consistent with previous chemical analyses of PM. © 1998 Society of Automotive Engineers, Inc.

ANTHROPOGENIC ORGANIC CONTAMINANTS IN WATER AND SURFACE SEDIMENTS OF LARGE SHALLOW EUTROPHIC CHAOHU LAKE, CHINA

To characterize the contamination of anthropogenic organic contaminants in the aquatic environment of Chaohu Lake, China, 7 samples for both water and surface sediment were collected in the lake. Organic contaminants were extracted by solid phase extraction (SPE) and Soxhlet extraction from the water and surface sediment samples, respectively, and then analyzed by GC-MS. One hundred and twenty kinds of organic chemicals were detected in these samples including phenol, benzene series, benzaldehydes, ethanol, polycyclic aromatic hydrocarbons (PAHs), sulfur compounds, alcoholic halides, amines, ketones, esters, alkenes and alkanes. Among them, 13 kinds of chemicals were identified as priority pollutants listed by the U.S. Environmental Protection Agency (EPA), such as phthalate esters (PAEs) and PAHs. Besides, the concentrations of 19 of PAEs and PAHs including, priority pollutants identified were also determined. Bis(2-ethylhexyl)phthalate, the predominant component of the analyzed pollutants, was in the range from 72.34 ng g(-1) DW to 613.71 ng g(-1) DW, 14.80 ng L-1 to 47.05 ng L-1 in sediment and water, respectively. The results indicated that the northwest part of the lake was heavily polluted by domestic and industrial wastewater.

Determination of PAH, PCB, and OCP in water from the Three Gorges Reservoir accumulated by semipermeable membrane devices (SPMD)

Bioavailable water concentrations of polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB) and organochlorine pesticides (OCP) were measured in the water column from Three Gorges Reservoir (TGR) collected in May 2008 using semipermeable membrane devices (SPMDs). The sampling sites spanned the whole reservoir from the upstream Chongqing to the great dam covering more than 600 km long distance with water flow velocities ranging from <0.05 to 1.5 m s(-1). This is the first experience of SPMD application in the biggest reservoir in the world. The results of water sampling rates based on performance reference compounds (PRC) were tested to be significantly correlated with water flow velocities in the big river. Results of back-calculated aqueous concentrations based on PRC showed obvious regional variations of PAH, PCB and OCP levels in the reservoir. Total PAH ranged from 13.8 to 97.2 ng L-1, with the higher concentrations occurring in the region of upstream and near the dam. Phenanthrene, fluoranthene, pyrene and chrysene were the predominant PAH compounds in TGR water. Total PCB ranged from 0.08 to 0.51 ng L-1, with the highest one occurring in the region near the dam. PCB 28, 52, 101, 138, 153, 180, 118 were the most abundant PCB congeners in the water. The total OCP ranged from 2.33 to 3.60 ng L-1 and the levels showed homogenous distribution in the whole reservoir. HCH, DDT and HCB, PeCB were the major compounds of OCP fingerprints. Based on water quality criteria, the TGR water could be designated as being polluted by HCB and PAH. Data on PAH, PCB and OCP concentrations found in this survey can be used as reference levels for future POP monitoring programmes in TGR. (C) 2009 Elsevier Ltd. All rights reserved.

How polluted is the Yangtze River? Water quality downstream from the Three Gorges Dam

The concentrations of major anions and cations, nitrogen and phosphorus, dissolved and particulate trace elements, and organic pollutants were determined for the middle and lower reaches of the Yangtze River (Changjiang) from below the Three Gorges Dam (TGD) to the mouth at Shanghai in November 2006. The concentration of dissolved inorganic phosphate (DIP) was constant at a low level of 6-8 mu gP/L, but the concentration of nitrate (NO3-) approximately doubled downstream and was closely correlated with K+. This translated to a daily load of well over 1000 It of dissolved inorganic nitrogen (DIN) at Datong. The average concentrations of dissolved Pb (0.078 +/- 0.023 mu g/L), Cd (0.024 +/- 0.009 mu g/L), Cr(0.57 +/- 0.09 mu g/L), Cu (1.9 +/- 0.7 mu g/L), and Ni (0.50 +/- 0.49 mu g/L) were comparable with those in other major world rivers, while As (3.3 +/- 1.3 mu g/L) and Zn (1.5 +/- 0.6 mu g/L) were higher by factors of 5.5 and 2.5, respectively. The trace element contents of suspended particles of As (31 +/- 28 mu g/g), Pb (83 +/- 34 mu g/g), and Ni (52 +/- 16 mu g/g) were close to maximum concentrations recommended for rivers by the European Community (EC). The average concentrations of Cd (2.6 +/- 1.6 mu g/g), Cr (185 +/- 102 mu g/g), Cu (115 +/- 106 mu g/g), and Zn (500 +/- 300 mu g/g) exceeded the EC standards by a factor of two, and Hg (4.4 +/- 4.7 mu g/g) by a factor of 4 to 5. Locally occurring peak concentrations exceed these values up to fourfold, among them the notorious elements As, Hg, and Tl. All dissolved and particulate trace element concentrations were higher than estimates made twenty years ago [Zhang, J., Geochemistry of trace metals from Chinese river/estuary systems: an overview. Estuar Coast Shelf Sci 1995; 41: 631-658.]. The enormous loads of anthropogenic pollutants disposed to the river were diluted by the large water discharge of the Yangtze even during the lowest flow resulting in the relatively low concentration levels of trace elements and organic pollutants observed. We estimated loads of e.g. As, Pb and Ni to the East China Sea to be about 4600 kg As d(-1), 3000 kg Pb d(-1), and 2000 kg Ni d(-1). About 6000 t d(-1) of dissolved organic carbon (DOC) was delivered into the sea at the time of our cruise. We tested for 236 organic pollutants, and only the most infamous were found to be barely above detection limits. We estimated that the load of chlorinated compounds, aromatic hydrocarbons, phenols, and PAHs were between 500 and 3500 kg d(-1). We also detected eight herbicides entering the estuary with loads of 5-350 kg d(-1). The pollutant load, even when at low concentrations, are considerable and pose an increasing threat to the health of the East China Sea ecosystem. (c) 2008 Elsevier B.V. All rights reserved.

Apoptosis induction on human hepatoma cells Hep G2 of decabrominated diphenyl ether (PBDE-209)

Polybrominated diphenyl ethers (PBDEs) are an important class of halogenated organic brominated flame retardants. Because of their presence in abiotic and biotic environments widely and their structural similarity to polychlorinated biphenyls (PCBs), concern has been raised on their possible adverse health effects to humans. This study was designed to determine the anti-proliferative, apoptotic properties of decabrominated diphenyl ether (PBDE-209), using a human hepatoma Hep G2 line as a model system. Hep G2 cells were cultured in the presence of PBDE-209 at various concentrations (1.0-100.0 mu mol/L) for 72 h and the percentage of cell viability was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. The results showed that PBDE-209 inhibited the cells viability in time and concentration-dependent characteristics at concentrations (10.0-100.0 mu mol/L). We found that anti-proliferative effect of PBDE-209 was associated with apoptosis on Hep G2 cells by determinations of morphological changes, cell cycle and apoptosis. Mechanism study showed that PBDE-209 could increase the generation of intracellular reactive oxygen species (ROS) concentration-dependently. Antioxidant N-acetylcyteine partially inhibited the increase of ROS. The mechanism for its hepatoma-inhibitory effects was the induction of cellular apoptosis through ROS generation. In addition, activity of lactate dehydrogenase (LDH) release increased when the cells incubated with PBDE-209 at various concentrations and times. These results suggested that PBDE-209 had the toxicity activity of anti-proliferation and induction of apoptosis in tumor cells in vitro. (c) 2007 Elsevier Ireland Ltd. All rights reserved.

EROD activities in a primary cell culture of grass carp (Ctenopharyngodon idellus) hepatocytes exposed to polychlorinated aromatic hydrocarbonas

Aryl hydrocarbon (Ah) receptor (Ah-agonist) effects of environmental samples containing polychlorinated aromatic hydrocarbons were evaluated using a 7-ethoxyresorufin-O-deethylase (FROD) assay of a primary hepatocyte culture from grass carp (Ctenopharyngodon idellus). The results were compared with those obtained from the assay using the rat hepatoma cell line H4IIE and chemical analysis using high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS). A dose-response relationship was observed between the EROD activities, either from primary hepatocyte culture assay or from H4IIE assay, and concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). The results showed that the assay based on the H4IIE cell line (EC50 = 0.83 mug/mL) is more sensitive to TCDD than the assay based on primary hepatocyte Culture (EC50 = 9.7 pg/mL). In tests of environmental samples, the results from the assay using primary hepatocyte culture were comparable to those from the assay using the H4IIE cell line and chemical analysis of concentrations of mixtures of polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/PCDF). The lack of a change in the activities of glutathione-S-transferase (GST) and lactate dehydrogenase (LDH) in cell culture upon exposure to TCDD indirectly indicates that the compound is persistent to biodegradation in the cell culture system. (C) 2004 Elsevier Inc. All rights reserved.

Water solubility enhancement of phthalates by cetyltrimethylammonium bromide and beta-cyclodextrin

Water solubility enhancements of six phthalates (five aliphatic phthalates and one phenyl phthalate) by cetyltrimethylammonium bromide (CTAB) and beta-cyclodextrin (beta-CD) were studied at 25 degreesC. The solubilities of these plithalates are remarkably enhanced by CTAB solutions above the critical micelle concentration (cmc). Only marginal enhancement of phthalate solubility was observed in solutions containing CTAB below its cmc and beta-CD at low concentrations (less than 5 mM). The solubility enhancements of the plithalates are proportional to the added amount of CTAB and beta-CD. Partition coefficients of the plithalates between monomeric CTAB surfactant and water (K-MN) and between CTAB micelle and water K-MC) were estimated from the experimental data. The mechanisms of solubility enhancements by CTAB and beta-CD were discussed. A log-linear equation was proposed and evaluated for the solubilization by CTAB below cmc, while the previously proposed linear partitioning model was questioned. The structures of the complexes formed between plithalates and beta-CD were proposed, and the formation constants were estimated. The values of log K-MC, log K-MN, and log Kbeta-CD of the plithalates were found to correlate linearly with the log K-OW of plithalates, with the exception of the solid phenyl phthalate.

Efficiently producing single-walled carbon nanotube rings and investigation of their field emission properties

Single-walled carbon nanotube (SWNT) rings with a diameter of about 100 nm have been prepared by thermally decomposing hydrocarbon in a floating catalyst system. These rings appeared to consist mostly of SWNT toroids. High resolution transmission electron microscopy showed that these rings were composed of tens of SWNTs with a tightly packed arrangement. The production of SWNT rings was improved through optimizing various growth parameters, such as growth temperature, sublimation temperature of the catalyst, different gas flows and different catalyst components. The growth mechanism of the SWNT rings is discussed. In the field emission measurements we found that field emission from a halved ring is better than that from a whole SWNT ring, which contributed to the better emission from two opened ends of the nanotubes of the halved SWNT ring.

Gasoline-range hydrocarbon synthesis over cobalt-based Fischer-Tropsch catalysts supported onSiO2/HZSM-5

Two types of SiO2 with different mesopore size and HZSM-5 zeolite were used to prepare hybrid supported cobalt-based catalysts. The textual and structural properties of the catalysts were studied using N-2 physisorption, X-ray diffraction (XRD), and H-2 temperature-programmed reduction (TPR) techniques. Fischer-Tropsch synthesis (FTS) performances of the catalysts were carried out in a fixed-bed reactor. The combination effects of the meso- and micropores of the supports as well as the interaction between supports and cobalt particles on FTS activity are discussed. The results indicate that the catalyst supported on the tailor-made SiO2 and HZSM-5 hybrid maintained both meso- and micropore pores during the preparation process without HZSM-5 particles agglomerating. The mesopores provided quick mass transfer channels, while the micropores contributed to high metal dispersion and accelerated hydrocracking/hydroisomerization reaction rate. High CO conversion of 83.9% and selectivity to gasoline-range hydrocarbons (C-5-C-12) of 55%, including more than 10% isoparaffins, were achieved simultaneously on this type of catalyst.

微生物固定化方法修复多环芳烃污染土壤

针对传统游离微生物修复技术的缺点和弊端，提出了采用固定化微生物技术修复受多环芳烃污染的非流体介质的新课题。本文筛选出2株高效降解菌，并进行了固定化载体筛选，优化并确定了3种固定化工艺。通过实验室模拟实验，考察了固定化菌对PAHs污染非流体介质的修复能力，最后通过扫描电子显微镜（SEM）分析，对固定化微环境强化修复机制进行了初步探讨。 细菌芽孢杆菌（Bacillus sp.，SB02）和真菌毛霉（Mucor sp.，SF06）对土壤中的Pyr、BaP降解率高，降解速率快，为高效降解微生物。 碱化后的泥炭土适宜作为细菌固定化载体；玉米芯适宜作为真菌固定化载体；改性后蛭石适宜作为混合菌固定化载体。这些载体来源广泛，成本低廉，工艺简单，安全无毒。 将固定化菌应用于Pyr、BaP污染土壤的修复，考察了初始接种量、环境温度、土壤含水量对固定化菌降解Pyr、BaP的影响，固定化菌对不同系列浓度Pyr、BaP的降解，以及固定化菌在不灭菌土壤中对Pyr、BaP的降解，表明固定化菌对土壤中Pyr和BaP的降解率均高出游离菌20%，固定化混和菌降解效果最好，其次是固定化真菌，再次是固定化细菌。 SEM分析了固定化颗粒的微观结构和微生物在颗粒内部的形态变化，结果表明颗粒内部丰富的疏松多孔结构和巨大的比表面积为微生物提供了适宜的生存空间，使吸附固定化成为可能。 固定化菌对沈抚灌区PAHs污染土壤修复效果非常理想，经过6个月，土壤中总PAHs的去除率达70.3%，高于游离菌。

土壤中PAHs的光催化降解动力学及机制研究

本文以土壤为介质，以三环的菲（Phe）、四环的芘（Pyr）和五环的苯并[a]芘（BaP）为目标污染物，研究了紫外灯照射下土壤中多环芳烃（PAHs）的降解，并以半导体纳米TiO2和Fe2O3为催化剂研究了土壤中PAHs的催化降解，对光降解及光催化降解的动力学进行了研究，在室内条件下考察了土壤条件和环境因子对光降解及光催化降解PAHs的影响；研究了太阳光照条件下土壤pH值对光降解和催化降解的影响和腐殖酸对光降解的影响；初步探讨了纳米TiO2催化光降解土壤中PAHs的机制。 研究结果表明：土壤中PAHs的紫外光降解符合一级动力学模型，土壤中PAHs光降解与土壤厚度呈显著负相关，土壤粒径对紫外光解PAHs有显著影响，温度从20 ℃升高到30 ℃，光解速率逐渐增加，在PAHs污染土壤的光降解中腐殖酸起敏化作用，随着紫外辐射强度的增加，光降解速率加快。 纳米TiO2和Fe2O3均能促进土壤中PAHs的紫外光降解，PAHs光催化降解符合一级动力学模型，在酸性和碱性土壤条件下，光催化降解PAHs的速率均高于中性，在不同光质条件下，TiO2 、Fe2O3催化光降解PAHs的速率发生变化，随着紫外辐射强度的增加，光催化降解速率常数增加，半衰期减少；腐殖酸促进TiO2 、Fe2O3催化土壤中PAHs的光降解，腐殖酸在这个过程中起着敏化作用。 在太阳光照射下酸性和碱性土壤中PAHs的降解快于中性，PAHs污染土壤中在加入腐殖酸后光降解速率加快，在酸性条件下催化降解最快，在碱性和中性条件下相差不大。 土壤中PAHs存在着PAH的光致电离、电子向O2的转移的两种降解途径；在有催化剂TiO2条件下，由于催化剂在光照后形成的电子-空穴能够氧化还原污染物，PAH的光致电离、电子向O2的转移的引起的降解，共同促进了土壤中PAHs的光催化降解。

植物与微生物联合修复多环芳烃污染土壤及机理研究

本文以多环芳烃污染土壤为研究对象，以菲（Phe）、芘（Pyr）和苯并[a]芘（BaP）为目标污染物，以建立生态、经济、高效污染土壤修复技术为目标，在研究植物与微生物联合修复多环芳烃污染土壤效果的基础上，重点研究了植物与微生物联合修复污染土壤过程中多环芳烃的去除机制。 研究结果表明：种植苜蓿和黑麦草能够促进土壤中多环芳烃的去除，提高土壤中多环芳烃的去除率。植物根际土壤中多环芳烃的去除速度快于于非根际土壤。在植物与高效降解菌联合作用过程中，植物的存在强化了菌剂对土壤中多环芳烃的去除作用。苜蓿和黑麦草与高效降解菌的联合作用使菲、芘和苯并[a]芘去除率分别比对照土壤提高了26.64%、30.41%、32.04%和26.93%、27.43%、30.15%。 植物根和茎叶中菲、芘和苯并[a]芘的含量与土壤污染物浓度正相关，但其吸收积累作用对土壤中多环芳烃去除的贡献率小于0.34%。植物对土壤多环芳烃污染的修复作用主要源于植物生长显著提高了根际微生物的降解活性。 植物根际微生物的数量和土壤酶活性显著高于非根际土壤。植物根系的存在提高了土壤中微生物的数量和酶活性，从而提高了土壤中PAHs的去除率。这是根际土壤中多环芳烃去除的主要机制。 模拟根际修复，研究了添加根系分泌物对土壤中芘降解的影响。添加20mg/kg根系分泌物土壤中细菌数量为未添加根系分泌物土壤的19.43-36.29倍，真菌为3.05-6.60倍，土壤中芘的半衰期比未添加根系分泌物处理减少10.91天。植物根系分泌物是影响根际修复的一个重要原因。

用植物油淋洗修复多环芳烃污染土壤

研究用植物油淋洗修复多环芳烃污染土壤的效果、植物油淋洗剂再生与回用的可行性、植物油的生态效应。采用了批处理法和土柱法对多环芳烃污染土壤进行修复，结果表明：油土比1：1的条件下，批处理法可以去除土壤中90％以上的多环芳烃，多环芳烃的质量转移过程可以用经验模型模拟。恰当的运行条件下，土柱法可去除土壤中90％以上的多环芳烃，但是根据土壤中多环芳烃浓度的高低，植物油的用量是批处理法的2～4倍。无论是批处理法，还是土柱法，土壤水分含量都影响了植物油去除土壤中多环芳烃的能力。采用了化学氧化法、溶剂提取法和吸收剂吸收法对植物油进行再生，结果表明：臭氧和双氧水能氧化植物油中的多环芳烃，但不理想，紫外线及双氧水在pH＝3的条件下可氧化植物油中76.5％的多环芳烃。按植物油／乙醇1:3的比例对植物油进行6级处理可氧化植物油中87％的多环芳烃。活性炭二级处理可去除植物油中87％的多环芳烃，实现植物油的再生。高等植物生长实验说明土壤中的植物油对燕麦及萝卜的生长起了抑制作用，土壤呼吸实验证明，残留在土壤中的植物油可被生物降解，但是必须保证良好的氧气及营养供应。用植物油修复多环芳烃污染土壤具有可行性。

石油烃污染土壤植物-微生物联合修复及机理研究

运用土壤学、微生物学、生态学和统计学方法，系统地开展了石油污染土壤的植物-微生物联合修复研究，对植物-微生物修复的生态影响进行了分析，并从根际微生物区系变化与根分泌物特性两个角度深入探讨了污染土壤植物一微生物联合修复的机理。室内模拟、室外盆栽、田间微区实验的结果表明：（1）植物-微生物联合修复对不同浓度石油烃污染土壤有较好的修复效果，125d的修复周期中对土壤中石油污染物的降解率为7.1％-69.8％，随污染物浓度的升高，联合修复对土壤中污染物的降解作川增强；（2）植物一微生物联合修复作用可能会长期持续，并对难降解物质PAHs存在修复潜力；（3）在本实验条件下，采用经济作物与降解微生物联合修复会降低土壤有机质含量，对土壤生态系统的结构和功能不会产生严重的干扰，对土壤生态环境的影响可以在短时间恢复；（4）植物一微生物联合作用方式在于植物与微生物的相互作用，作用区为植物根际，微生物在植物根际区域的种类数量和生化特征存在差异；植物分泌物对于微生物具有调节作用，促使污染物的生物降解。并以本试验研究为例，进一步探讨石油污染土壤植物一微生物联合修复的机理，利石油污染土壤的植物一微生物联合修复的影响因子进行调控研究，联合修复的主要影响因子是营养因子，其次是污染物浓度。石油污染土壤的植物一微生物联合修复研究，对土壤微生物群落，植物根际效应及潜在自然生物降解获得了进一步的理解，为污染土壤修复技术提供了科学依据和理论支持。