Passive and Active Sampling of Benzene in Different Urban Environments in Gothenburg, Sweden

Urban benzene concentration and personal exposure to benzene were measured within different urban environments in Gothenburg, Sweden. Three intensive monitoring campaigns were carried out in May 2000, February 2001 and May 2001. Three different environments were selected; two central built-up areas with different traffic densities (high and low) and one large urban park. The methods used included passive and active sampling. Passive sampling was used to retrieve spatial variability in urban benzene concentrations, while active sampling aimed to give data on personal exposure levels within the designated areas. The passive sampling showed large spatial and temporal variations in urban benzene concentrations. The benzene concentrations, ranging from 1.0 to 3.1 μg m^?3, were typically two to four times higher within the high-traffic built-up area compared to the adjacent urban park. This was mainly due to the proximity to motorised traffic. A comparison between personal exposure and active stationary measurements showed that the personal exposure levels were roughly 1.5 times higher in the heavy traffic area and 1.3 times higher in the light traffic area than the fixed benzene concentrations. The personal exposure levels in the park were equal to the active stationary benzene concentration. Given the large spatial heterogeneity within urban areas, the placement of single street level point measurements becomes crucial. Care must be taken to ensure that the measurements are actually representative when using these measurements to estimate urban concentrations and exposure levels.     

土壤苯污染引起的饮用地下水健康风险评价

由于污染场地所引起的生态环境、食品安全和人体健康问题,污染场地的环境风险评价受到广泛关注。以某水源地油和苯等有机污染调查为依据,利用多介质暴露评价模型(MMSOILS模型),以苯为评价的目标污染物,分析烯烃厂不同分区的土壤苯污染对A地区造成的饮用地下水健康风险。结果表明,研究区4个分区中,裂解装置区的苯污染物释放是A地区地下水污染的主要来源,产生的饮水健康风险值为9.82×10-5,占总风险值的98.8%;而其他三个分区的影响较小;不同分区苯污染对A地区产生的饮水健康总风险值为9.94×10-5,大于美国环境保护署人体健康风险建议值10-6,对人体健康已经产生影响;裂解装置区的土壤苯污染作为饮水健康风险的主要来源,当其浓度值降低至1.32mgkg-1时,才能使其造成的饮水健康风险降低为10-6。     

脆弱刚毛藻对水体中三种苯系物的去除效果

采用L934正交设计法,研究了脆弱刚毛藻[Cladophora fracta (Dillw.) Kuetz.]对水体中3种苯系物苯、甲苯和二甲苯的去除作用.结果表明,脆弱刚毛藻对苯、甲苯和二甲苯的去除率分别为46.6写,13.6%和7.4 Yo.分析不同处理条件对脆弱刚毛藻对苯去除率的影响,各因素极差值大小依次为:温度>处理时间>藻体重量,温度是影响去除笨效果的主要因素.在刚毛藻去除甲苯的实验中,各因素R值大小依次为处理时间>藻体重量>温度,主要影响因素是处理时间.而对于二甲苯,藻体重量则是最主要的因素.     

Factors influencing benzene formation from the decarboxylation of benzoate in liquid model systems

Benzene may occur in foods due to the oxidative decarboxylation of benzoate in the presence of hydroxyl radicals. This study investigated factors influencing benzene formation in liquid model systems. The type of buffer, other sources of hydroxyl radical formation in food (photo oxidation of riboflavin and lipid oxidation), transition metal ion concentrations, and the inhibitory effect of antioxidants were tested in benzoate containing model systems. Regarding the hydroxyl radical sources tested, the highest benzene formation was observed in light exposed model systems containing ascorbic acid, Cu(2+), and riboflavin in Na-citrate buffer (1250 ± 131 μg kg(-1)). In practice, it seems that the combination ascorbic acid/transition metal ion remains the biggest contributor to benzene formation in food. However, the concentration of Cu(2+) influences significantly benzene formation in such a system with highest benzene yields observed for Cu(2+) 50 μM (1400 μg kg(-1)). The presence of antioxidants with metal chelation or reduction properties could prevent completely benzene formation.     

The Relationship Between Indoor, Outdoor and Personal VOC Concentrations in Homes, Offices and Schools in the Metropolitan Region of Kocaeli, Turkey

Human exposure to volatile organic compounds (VOCs) and residential indoor and outdoor VOC levels had hitherto not been investigated in Turkey. This study details investigations of indoor, outdoor, and personal exposure to VOCs conducted simultaneously in 15 homes, 10 offices and 3 schools in Kocaeli during the summer of 2006 and the winter of 2006–2007. All VOC concentrations were collected by passive sampling over a 24-h period and analyzed using thermal desorption (TD) and a gas chromatography/flame ionization detector (GC/FID). Fifteen target VOCs were investigated and included benzene, toluene, m/p-xylene, o-xylene, ethylbenzene, styrene, cyclohexane, 1,2,4-trimethylbenzene, n-heptane, n-hexane, n-decane, n-nonane, n-octane and n-undecane. Toluene levels were the highest in terms of indoor, outdoor, and personal exposure, followed by m/p-xylene, o-xylene, ethylbenzene, styrene, benzene and n-hexane. In general, personal exposure concentrations appeared to be slightly higher than indoor air concentrations. Both personal exposure and indoor concentrations were generally markedly higher than those observed outdoors. Indoor target compound concentrations were generally more strongly correlated with outdoor concentrations in the summer than in winter. Indoor/outdoor ratios of target compounds were generally greater than unity, and ranged from 0.42 to 3.03 and 0.93 to 6.12 in the summer and winter, respectively. Factor analysis, correlation analyses, indoor/outdoor ratios, microenvironment characteristics, responses to questionnaires and time activity information suggested that industry, and smoking represent the main emission sources of the VOCs investigated. Compared with the findings of earlier studies, the level of target analytes in indoor air were higher for several target VOCs, indicating a possible trend toward increased inhalation exposure to these chemicals in residential environments.     

Monitoring BTEX and Aldehydes in Car Exhaust from a Gasoline Engine During the Use of Different Chemical Cleaners by Solid Phase Microextraction-Gas Chromatography

All commercial gasoline fuels build up deposits on the spark plugs, injectors, oxygen sensors, catalytic converter, and inside the combustion chamber, which will lower the engine's performance and increase air pollution. As a result, fuel-based detergents have been developed to prevent and remove unwanted deposits. Unfortunately, many of the detergents use high amounts of aromatic solvents, which result in a greater risk of exposure to aromatic compounds like benzene. In this study, car exhaust was analyzed for benzene, toluene, ethylbenzene, and xylenes (BTEX), as well as formaldehyde and acetaldehyde during engine cleaning service using different chemical cleaners. A special device was designed for sampling from car exhaust using solid phase microextraction. The extracted compounds were analyzed using a gas chromatograph with flame ionization detector. The cleaning products were rated with regard to the amount of pollutants produced during the cleaning service.     

Removal of Benzene Using the Characteristics of Block Copolymers for Encapsulation

This study assessed the aqueous benzene removal capacity of a polymeric adsorbent, based on an amphiphilic material, in a batch experiment. Two types of polystyrene-block-poly(N-isopropylacrylamide) have structures containing a hydrophobic core and hydrophilic shell. The encapsulation mechanism of benzene by a polymeric adsorbent was investigated, and found to be attributable to the Van der Waals interactions between the benzene aromatic ring and the hydrophobic core of the adsorbent. The equilibrium data were analyzed using the Langmuir and Freundlich adsorption isotherms, and found to be a good fit to both. The maximum adsorption capacity for benzene by the polymeric adsorbent was found to be 194.53 mg/g. The kinetic data followed a pseudo-first-order kinetic model. Polystyrene-block-poly(N-isopropylacrylamide) showed the potential to be an effective adsorbent for application to wastewater treatment.     

A Comprehensive Study of Deep Catalytic Oxidation of Benzene, Toluene, Ethyl Acetate, and their Mixtures over Pd/ZSM-5 Catalyst: Mutual Effects and Kinetics

Reaction behaviors and kinetics of catalytic oxidation of benzene, toluene, and ethyl acetate with feed concentrations in the range of 700–5,000 ppm over Pd/ZSM-5 catalyst were investigated. Results for single components show that ethyl acetate (T ₅₀?=?190–200°C) is more easily oxidized than benzene (T ₅₀?=?215–225°C) and toluene (T ₅₀?=?225–235°C). The conversion of ethyl acetate was increased with the increase of its feeding concentration, while the opposite behaviors were observed for benzene and toluene as their conversion rates were decreased with the increase of the inlet concentration. Different behaviors were observed in catalytic oxidation of volatile organic compound (VOC) multi-components, the presence of benzene or toluene inhibits the conversion of ethyl acetate, and the aromatic hydrocarbons inhibit each other in all cases. Ethyl acetate possesses obvious inhibitory effect on benzene oxidation, while it is interesting to note that ethyl acetate has a promotion effect on toluene conversion. The kinetic data were fitted by the Power-law and Mars–van Krevelen kinetic models. The fitting result shows that the Power-law model is more suitable for predicting the conversion of benzene than the other VOCs, and the Mars–van Krevelen model can accurately express the reaction rate of all investigated VOCs.     

Interactive responses of gala apple fruit volatile production to controlled atmosphere storage and chemical inhibition of ethylene action

Gala apples exposed to the ethylene action inhibitor 1-methylcyclopropene (1-MCP) for 12 h at 20 degrees C were stored at 1 degrees C in air or a controlled atmosphere (CA) maintained at 1 kPa O2 and 2 kPa CO2. Volatile compounds were measured after 4, 12, 20, and 28 weeks plus 1 or 7 days at 20 degrees C. Treatment with 1-MCP and then storage in air or CA or storage in CA without 1-MCP treatment reduced volatile production as compared to apples not treated with 1-MCP stored in air. The reduced production of esters, alcohols, aldehydes, acetic acid, and 1-methoxy-4-(2-propenyl)benzene was observed. Ester production by fruit stored in CA decreased throughout the storage period regardless of previous 1-MCP treatment. The production of esters, alcohols, aldehydes, acetic acid, and 1-methoxy-4-(2-propenyl)benzene by 1-MCP-treated fruit stored in air plus 7 days at 20 degrees C increased after 20 or 28 weeks of storage. Continuous exposure to 417 micromol m(-3) ethylene for 7 days at 20 degrees C after 12 or 28 weeks of storage stimulated production of many volatile compounds, primarily esters and alcohols, by fruit stored in CA or 1-MCP-treated apples stored in air. However, exposure to ethylene had no effect on the production of aldehydes or acetic acid.     

工业遗留场地复合型污染分层健康风险评估研究

以某典型有机物-重金属复合型污染场地为研究对象,根据该场地水文地质特征将土层划分为回填土(0~4.1 m)、粉质黏土(4.1~6.5 m)、粉土(6.5~8.5 m)和粉砂(8.5~13.8 m)等4层,运用HERA软件分别进行健康风险评估,推算了土壤和地下水的风险值及修复目标值,并以此划分修复范围和确定修复技术。结果表明,土壤中存在严重的有机污染(苯和甲苯)和重金属(Cr(Ⅵ))污染,苯的最大致癌风险为0.000 155,甲苯的最大非致癌危害商为2.14;Cr(Ⅵ)在下层土壤中不存在暴露途径危害人体健康,而仅在表层回填土中存在致癌和非致癌危害商(0.014 2和97.6);地下水中关注污染物健康风险在可接受范围内;苯、甲苯在各土层中的修复目标值分别为:回填土层0.434、708 mg/kg;粉质黏土层0.807、2 460 mg/kg;粉土层1.42、4 440 mg/kg;粉砂层2.51、8 140 mg/kg;Cr(Ⅵ)仅在回填土层计算出修复目标值为0.251 mg/kg。苯、甲苯等挥发性有机物分层修复目标值随土层深度增加而变大,Cr(Ⅵ)等重金属修复目标值不遵循这个规律,因此,分层健康风险评估更适用于挥发性有机物健康风险评价。     

Development of an Amendment Recipe and Identification of Benzene Degraders for Anaerobic Benzene Bioremediation

This study aims to develop an optimal recipe of amendment (nutrients and electron acceptors) for anaerobic benzene bioremediation and identify the dominant indigenous benzene-degrading microorganisms in soil and groundwater collected from a fuel service station. Lessons learned in developing and optimizing the amendment recipe follow: (1) salinity and a high initial concentration of benzene were detrimental for benzene biodegradation, (2) a large dose of amendment can shorten the lag time for benzene biodegradation, (3) toluene was an essential co-substance for promoting benzene biodegradation. Stable isotope probing was used to identify microorganism incorporation of ¹³C from ¹³C– benzene. Under the experimental conditions, incorporation of ¹³C can be considered direct evidence of the occurrence of benzene biodegradation. Quantitative polymerase chain reaction showed the primary mechanism for benzene removal to be nitrate reduction. Microbial analyses (denaturing gradient gel electrophoresis and 16S ribosomal RNA) demonstrated that members of genus Dokdonella spp., Pusillimonas spp., and Advenella spp. were predominant in the microbial community and involved in anaerobic benzene bioremediation.     

Detoxification Potential of Pseudomonas fluorescens SM1 Strain for Remediation of Major Toxicants in Indian Water Bodies

The present investigation was carried out to evaluate the detoxification potential of Pseudomonas fluorescens SM1 strain immobilized in calcium alginate beads for some major toxicants of Indian water bodies. The toxicants selected in this study were benzene hexachloride, mancozeb, 2,4-dichloro-phenoxyacetic acid (pesticides); phenol, catechol, cresol (phenolics); and Cd⁺⁺, Cr(VI), Cu⁺⁺ and Ni⁺⁺ (heavy metals), which were taken as mixtures up to a concentration of roughly twice that usually found in highly polluted sites. Allium cepa phytotoxicity test, Ames fluctuation test and plasmid nicking assay were employed to estimate the phytotoxicity and genotoxicity of the model water containing the test toxicants under different combinations before and after exposure to our bioremediation-cum-detoxification system. The IC₅₀ of the model water containing all the test toxicants, treated with the immobilized SM1 cells, was recorded to be 0.7× compared to 0.06× for the same but untreated water sample, enhancing the IC₅₀ value by 12-fold. The IC₂₅ of the test heavy metal mixture only could enhance from 0.07 to 1.30× (18-fold). The IC₂₅ of the test pesticide mixture alone was increased from 0.07 to 1.71× (24-fold). The IC₂₅ values for the mixture of test phenolics were 0.07× and 2.18× under the pre- and post-treatment conditions, respectively, exhibiting a 31-fold increase. A mutational induction (Mi) corresponding to the 0.5 value in the Ames fluctuation test was used to evaluate the mutagenicity of the test model water containing all the toxicants before and after exposure to the immobilized SM1 cell system. The Mi (0.5) value with the TA98 tester strain was estimated to be 0.08× for the untreated and 0.6× for the treated model water, whereas the same index was calculated to be 0.48× and 1.8×, respectively, for the TA100 strain. A remarkable improvement in the quality of the test water as a result of exposure to this bioremediating system was observed in terms of the absence of the linear form of the plasmid contrary to the visible linearization with the untreated model water. In view of the above findings, it is quite clear that the test of P. fluorescens SM1 strain immobilized in the calcium alginate beads could be used as an efficient system of bioremediation and for water decontamination strategies owing to its remarkable detoxification potential.     

Survey results of benzene in soft drinks and other beverages by headspace gas chromatography/mass spectrometry

Benzene, a carcinogen that can cause cancer in humans, may form at nanogram per gram levels in some beverages containing both benzoate salts and ascorbic or erythorbic acids. Through a series of reactions, a hydroxyl radical forms that can decarboxylate benzoate to form benzene. Elevated temperatures and light stimulate these reactions, while sugar and ethylenediaminetetraacetic acid (EDTA) can inhibit them. A headspace gas chromatography/mass spectrometry method for the determination of benzene in beverages was developed and validated. The method was used to conduct a survey of 199 soft drinks and other beverages. The vast majority of beverages sampled contained either no detectable benzene or levels below the U.S. Environmental Protection Agency's drinking water limit of 5 ng/g. Beverages found to contain 5 ng/g benzene or more were reformulated by the manufacturers. The amount of benzene found in the reformulated beverages ranged from none detected to 1.1 ng/g.     

Determination of benzene in polypropylene food-packaging materials and food-contact paraffin waxes

An analytical procedure was developed for determination of benzene in polypropylene food packaging and was adapted for determination of benzene in commercial paraffin waxes intended for food-contact use. The polymer was dissolved in hexadecane at 150 degrees C. The wax was melted in an 80 degrees C oven. A simple helium-sparging apparatus was used to remove the volatile chemical from the polymer or wax. The contaminant was collected in methanol, distilled water was added, and the resulting solution was analyzed by headspace gas chromatography. The instrument was equipped with a 30 m fused silica open tubular capillary column and a photoionization detector. Average recoveries of benzene from polymer and paraffin wax at low parts-per-billion concentrations were 63 and 70%, respectively. Limits of detection and quantitation for analysis of polypropylene were 8 and 17 ppb, respectively; the limit of quantitation for analysis of paraffin wax was 2 ppb. In several commercial polypropylene products examined, benzene levels ranged from none detected to 426 ppb. In 3 commercial waxes examined, concentrations of 16-73 ppb benzene were determined. The presence of benzene was confirmed by gas chromatography/mass spectrometry.     

The analysis and control of volatile hydrocarbon concentrations (e. g. benzene) during oil bioassays

It is well known that volatile hydrocarbons such as benzene, toluene, and xylene, which are abundant in many refined oils, affect phytoplankton growth. However, experiments to determine these effects in many cases have been improperly designed resulting in questionable conclusions. Experiments presented in this paper indicate that ambient benzene concentrations reported in the published literature may be lower than stated by an order of 10 to 100. By continuous monitoring the benzene concentration decrease was observed and it was possible to determine whether the loss was due to degassing because of loose closures or biological uptake. Unless tight closures are used benzene is quickly lost to the atmosphere (exponential decay rate ≌ 1.2d ^-1). Experiments demonstrated that benzene is quickly lost from cotton stoppered bioassay flasks that are typically used. Rubber stoppered flasks with little gaseous headspace showed minimum benzene loss. Biological uptake of benzene can be demonstrated when closures are secure and the effect of certain concentrations on growth can be correctly interpreted. Benzene concentrations above 10 to 20 ppm significantly reduce the growth rate of Skeletonema sp. The benzene concentration decreased quickly in 10 to 20 ppm benzene solutions implying metabolic uptake. These experiments indicate that proper closures and analysis of the volatile pollutant concentration during bioassay experiments increase the likelihood of correct interpretation and may yield additional insights into the causation factors.     

RBCA和Csoil模型在挥发性有机物污染场地健康风险评价中的应用比较

应用美国的RBCA模型和荷兰的Csoil模型对某挥发性有机物污染场地中的2种主要污染物1,2-二氯丙烷和1,2-二氯乙烷进行健康风险评价。结果表明,2种模型计算出的健康风险基本一致,除14号采样点存在潜在的健康风险外,其余各采样点的健康风险均在可接受的范围内。由土壤污染引起的各暴露途径中,直接经口摄入途径引起的健康风险最大,占65%以上;皮肤接触途径次之;呼吸摄入途径最小。在呼吸暴露途径中,室内挥发暴露明显比室外挥发暴露的健康风险大。Csoil模型计算出的所有采样点由地下水暴露途径引起的健康风险都超过土壤,说明由地下水暴露引起的健康风险不容忽视。RBCA模型在考虑地下水暴露途径时仅考虑了饮水摄入这一途径,与RBCA模型相比,Csoil模型在进行健康风险评价时特别考虑了洗澡暴露途径,对于地下水受到污染的场地来说,Csoil模型考虑得更全面,使用Csoil模型进行健康风险评价更具有针对性。     

IRON AND ALUMINIUM AS CEMENTING SUBSTANCES OF SOIL AGGREGATES

A method is described for extracting fractions of soil iron and aluminium without removing organic matter. The extraction is by acetylacetone in a non–polar solvent and is virtually complete in zoo h. Similar amounts of iron and aluminium are extracted by acetylacetone in either benzene or water, but organic matter is extracted in detectable amounts only by acetylacetone in water. Extraction in aqueous solution after acetylacetone in benzene removes only organic matter, with no appreciable release of iron and aluminium. Metals extracted by acetylacetone in benzene are therefore considered to be bonded to that part of the organic matter which is extracted by acetylacetone. Water alone does not extract significant amounts of organic matter after removal of iron and aluminium by acetylacetone in benzene. The refolding of the hydrophilic surface units of the organic matter, caused by non–polar solvents, may hinder the extraction by water.     

Produced Water Surface Spills and the Risk for BTEX and Naphthalene Groundwater Contamination

The widespread use of unconventional drilling involving hydraulic fracturing (“fracking”) has allowed for increased oil-and-gas extraction, produced water generation, and subsequent spills of produced water in Colorado and elsewhere. Produced water contains BTEX (benzene, toluene, ethylbenzene, xylene) and naphthalene, all of which are known to induce varying levels of toxicity upon exposure. When spilled, these contaminants can migrate through the soil and contaminant groundwater. This research modeled the solute transport of BTEX and naphthalene for a range of spill sizes on contrasting soils overlying groundwater at different depths. The results showed that benzene and toluene were expected to reach human health relevant concentration in groundwater because of their high concentrations in produced water, relatively low solid/liquid partition coefficient and low EPA drinking water limits for these contaminants. Peak groundwater concentrations were higher and were reached more rapidly in coarser textured soil. Risk categories of “low,” “medium,” and “high” were established by dividing the EPA drinking water limit for each contaminant into sequential thirds and modeled scenarios were classified into such categories. A quick reference guide was created that allows the user to input specific variables about an area of interest to evaluate that site’s risk of groundwater contamination in the event of a produced water spill. A large fraction of produced water spills occur at hydraulic-fracturing well pads; thus, the results of this research suggest that the surface area selected for a hydraulic-fracturing site should exclude or require extra precaution when considering areas with shallow aquifers and coarsely textured soils.     

Monitoring the benzene contents in soft drinks using headspace gas chromatography-mass spectrometry: a survey of the situation on the belgian market

Whenever benzoic acid is combined with ascorbic acid in acidic beverages such as soft drinks, benzene can be formed. To determine the current situation on the Belgian market, a headspace gas chromatographic-mass spectrometric method was developed, which needs little to no sample preparation. This method was then used to analyze 134 soft drinks sampled on the Belgian market by the Federal Agency for the Safety of the Food Chain. Thirty-three percent of the samples contained no detectable benzene, whereas the majority of the samples (47%) contained trace amounts below the limit of quantification of the method (0.3 microg L (-1)). Ten samples were above the European limit for benzene in drinking water of 1 microg L (-1), and one sample had a concentration of 10.98 microg L (-1), thereby exceeding the action limit for benzene in soft drinks of 10 microg L (-1) discussed at the Standing Committee on the Food Chain and Animal Health of the European Commission. Statistical analyses revealed that besides benzoic acid, ascorbic acid, and acidity regulators, the packing may also play an important role in benzene formation.     

Benzene Biodegradation under Anaerobic Conditions Coupled with Metal Oxides Reduction

Anaerobic benzene biodegradation was performed in batch experiments using Rhine River sediment as inoculum and amorphous Mn(IV) or Fe(III) as independent final electron acceptors. Benzene (4.5 μmol) was degraded in 80 and 710 days in batch experiments under Mn(IV) and Fe(III) reducing conditions, respectively. Highest benzene degradation rate, 0.07 μmol/day, was obtained under Mn (IV) reducing conditions, with soluble Mn(II) and CO₂ recoveries of 71.5% and 93% regarding to the stoichiometric values, respectively. Likewise, benzene biodegradation was performed in a continuous column coupled to the reduction of Mn(IV). Efficiency of benzene biodegradation was up to 97% under steady state operation in a sediment column operated continuously for more than 160 days. The carbon dioxide and Mn(II) recoveries were 88% and 77%, respectively, of the theoretical ratio according to the stoichiometry for benzene biodegradation.