Characterization of Volatile Organic Compounds (VOCs) and Their Sources in the Air of Izmir, Turkey

Air samples were collected in Izmir, Turkey at two (suburban and urban) sites during three sampling programs in 2002 and 2004 to determine the ambient concentrations of several monoaromatic, chlorinated and oxygenated volatile organic compounds (VOCs). Samples were analyzed for 60 VOCs using gas chromatography/mass spectrometry and 28 compounds were detected in most samples. On the average, urban air VOC concentrations were about four times higher than those measured at the suburban site. Toluene (40.6%) was the most abundant compound in suburban site and was followed by benzene (7.4%), o,m-xylene (6.5%), and 1,2-dichloroethane (5.1%). In urban site, toluene (30.5%), p-xylene (14.9%), o,m-xylene (11.4%), and ethyl benzene (7.2%) were the dominating compounds in summer. In winter, toluene (31.1%), benzene (23.9%), 1,2-dichloroethane (9.5%), and o,m-xylene (8.2%) were the most abundant compounds. Receptor modeling (positive matrix factorization) has been performed to estimate the contribution of specific source types to ambient concentrations. Six source factors (gasoline vehicle exhaust, diesel vehicle exhaust+residential heating, paint production/application, degreasing, dry cleaning, and an undefined source) were extracted from the samples collected in the urban site. Three source factors (gasoline vehicle exhaust, diesel vehicle exhaust, and paint production/application) were identified for the suburban site.  

Organic Liquids Storage Tanks Volatile Organic Compounds (VOCS) Emissions Dispersion and Risk Assessment in Developing Countries: The Case of Dar-Es-Salaam City, Tanzania

The emission estimation of nine volatile organic compounds (VOCs) from eight organic liquids storage tanks companies in Dar-es-Salaam City Tanzania has been done by using US EPA standard regulatory storage tanks emission model (TANKS 4.9b). Total VOCs atmospheric emission has been established to be 853.20 metric tones/yr. It has been established further that petrol storage tanks contribute about 87% of total VOCs emitted, while tanks for other refined products and crude oil were emitting 10% and 3% of VOCs respectively. Of the eight sources (companies), the highest emission value from a single source was 233,222.94 kg/yr and the lowest single source emission value was 6881.87 kg/yr. The total VOCs emissions estimated for each of the eight sources were found to be higher than the standard level of 40,000 kg/yr per source for minor source according to US EPA except for two sources, which were emitting VOCs below the standard level. The annual emissions per single source for each of the VOCs were found to be below the US EPA emissions standard which is 2,000~kg/yr in all companies except the emission of hexane from company F1 which was slightly higher than the standard. The type of tanks used seems to significantly influence the emission rate. Vertical fixed roof tanks (VFRT) emit a lot more than externally floating roof tanks (EFRT) and internally floating roof tanks (IFRT). The use of IFRT and EFRT should be encouraged especially for storage of petrol which had highest atmospheric emission contribution. Model predicted atmospheric emissions are less than annual losses measured by companies in all the eight sources. It is possible that there are other routes for losses beside atmospheric emissions. It is therefore important that waste reduction efforts in these companies are directed not only to reducing atmospheric emissions, but also prevention of the spillage and leakage of stored liquid and curbing of the frequently reported illegal siphoning of stored products. Emission rates for benzene, toluene, and xylene were used as input to CALPUFF air dispersion model for the calculation of spatial downwind concentrations from area sources. By using global positioning system (GPS) and geographical information system (GIS) the spatial benzene concentration contributed by organic liquid storage tanks has been mapped for Dar-es-Salaam City. Highest concentrations for all the three toxic pollutants were observed at Kigamboni area, possibly because the area is located at the wind prevailing direction from the locations of the storage tanks. The model predicted concentrations downwind from the sources were below tolerable concentrations by WHO and US-OSHA. The highest 24 hrs averaging time benzene concentration was used for risk assessment in order to determine maximum carcinogenic risk amongst the population exposed at downwind. Established risk for adult and children at 2.9×10^-3 and 1.9×10^-3 respectively, are higher than the acceptable US-EPA risk of 1×10^-6. It is very likely that the actual VOCs concentrations in some urban areas in Tanzania including Dar-es-Salaam City are much higher than the levels reported in this study when other sources such as petrol stations and motor vehicles on the roads are considered. Tanzania Government therefore need to put in place: an air quality policy and legislation, establish air quality guidelines and acquire facilities which will enable the implementation of air quality monitoring and management programmes.  

差分光谱法连续监测空气中SO2、NO2、苯、甲苯方法探讨

差分光谱法(简称DOAS)已广泛用于空气中SO2、NO2、苯、甲苯监测.通过对差分光谱法监测结果与其他传统仪器进行时比,发现用DOAS监测SO2、NO2与点式仪器有较好的一致性,但用DOAS系统监测苯、甲苯与气相色谱法有机物连续监测结果差异较大,相关性较差,运行有一定的局限性.另外,本文对DOAS的最佳运行条件进行了探讨,发现影响光强的氙灯老化和气候条件对DOAS系统运行有较大影响.  

气相色谱法测定环境空气中氯化苄和甲苯

用串联的乙醇吸收管收集环境空气中的氯化苄和甲苯，以毛细管柱分离，氢火焰检测器测定，保留时间定性，峰高定量。氯化苄平均浓度在４．２９ｍｇ／Ｌ～２１．４ｍｇ／Ｌ时，相对标准偏差在３．３％～４．６％之间；甲苯平均浓度为４．１８ｍｇ／Ｌ～２０．６ｍｇ／Ｌ时，相对标准差在４．４％～７．８％范围内。方法快速、灵敏度高，有较好的精密度与准确度。  

不同萃取剂气相色谱法测定水中硝基甲苯类化合物的方法比对研究

采用液-液萃取-毛细管柱气相色谱法,分别用苯和甲苯作萃取剂,对测定水中4种硝基苯类化合物的方法进行比对分析。从精密度、准确度、方法检出限等方面对这2种方法进行系统比对,对实际水样测定结果采用统计学中t检验法进行比对。评价用甲苯代替苯作萃取剂的可行性。结果表明,用甲苯完全可以代替苯。  

南京某地甲苯槽罐车燃烧事故应急监测案例分析与思考

突发性环境污染事故不仅破坏生态环境,制约社会发展,更威胁人类健康.环保部门如何加强应急监测能力建设,科学合理地处理应急监测中出现的问题,显得尤为重要.对一起突发性环境污染事故应急监测各个环节的优缺点进行了分析和思考,总结经验并提出建议,为同类突发环境污染事故的应急监测提供借鉴.  

Investigation of Mtbe and Aromatic Compound Concentrations at a Gas Service Station

Methyl tert-butyl ether (MTBE) has been used as a fuel additive at levels of 2–11% in Taiwan for the past decade. The purpose of this additive is to enhance the octane, replace the use of lead-based anti-knock gasoline additives and reduce aromatic hydrocarbons. However, it is possible that oxygenated fuel has a potential health impact. To determine the air quality impact of MTBE, measurements were made of ambient MTBE and other gasoline constituents at a service station. Additionally, environmental conditions (wind speed, wind direction, and temperature, etc.) that could affect concentrations of emission constituents were measured. Gas samples were analyzed for target MTBE and volatile organic compounds, e.g., benzene and toluene. Ambient samples were collected using Tenax adsorbent tubes for mass spectrometric analysis at a service station located in Changhua County, Taiwan. The resulting measured ambient air concentrations were compared with Taiwans regulatory standards for hazardous air pollutants. Subsequently, the factors controlling the formation of high-VOC levels at the service station and in the residential neighborhoods were identified. Additionally, the results can provide the Environmental Protection Agency (EPA) of Taiwan with useful information and prompt them to mandate this gas service station to install a refueling vapor recovery system.  

室内装饰装修材料中苯、甲苯、二甲苯含量测定法改进

采用毛细管气相色谱法,对室内装饰装修材料中的苯、甲苯、二甲苯的测定进行了改进。称取样品后,用N,N-二甲基甲酰胺稀释定容,CBP20毛细管柱分离,可同时测定苯、甲苯、二甲苯的含量,数据准确,操作简单。  

新型生物轻质陶块填料塔净化低浓度有机废气的试验研究

试验研究结果表明 ,轻质陶块附着生物膜后对废气的有机物的净化性能明显优于不锈钢环。轻质陶块完全可以取代常用的不锈钢环而成为生物膜填料塔的新型填料  

Atmospheric Volatile Organic Compound Monitoring. Ozone Induced Artefact Formation

Assessment of population exposure to VOC in ambient atmospheres is receiving heightened interest as the adverse health effects of chronic exposure to certain of these compounds are identified. Active (pumped) and passive samplers are the most commonly used devices for this type of monitoring. It has been shown, however, that these devices, along with all other preconcentration techniques, are susceptible to ozone interference. It is demonstrated that this interference occurs even at low ozone concentrations and that it may result in the under-estimation of population exposure. A convenient and effective ozone scrubbing method is identified and successfully applied and validated for both active and passive samplers for a range of VOC.