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1.
The atmosphere is a particularly difficult analytical system because of the very low levels of substances to be analysed,
sharp variations in pollutant levels with time and location, differences in wind, temperature and humidity. This makes the
selection of an efficient sampling technique for air analysis a key step to reliable results. Generally, methods for volatile
organic compounds sampling include collection of the whole air or preconcentration of samples on adsorbents. All the methods
vary from each other according to the sampling technique, type of sorbent, method of extraction and identification technique.
In this review paper we discuss various important aspects for sampling of volatile organic compounds by the widely used and
advanced sampling methods. Characteristics of various adsorbents used for VOCs sampling are also described. Furthermore, this
paper makes an effort to comprehensively review the concentration levels of volatile organic compounds along with the methodology
used for analysis, in major cities of the world. 相似文献
2.
Smith LA Stock TH Chung KC Mukerjee S Liao XL Stallings C Afshar M 《Environmental monitoring and assessment》2007,128(1-3):369-379
In the summer of 2003, ambient air concentrations of volatile organic compounds (VOCs) were measured at 12 sites within a
3-km radius in Deer Park, Texas near Houston. The purpose of the study was to assess local spatial influence of traffic and
other urban sources and was part of a larger investigation of VOC spatial and temporal heterogeneity influences in selected
areas of Houston. Seventy 2-h samples were collected using passive organic vapor monitors. Most measurements of 13 VOC species
were greater than the method detection limits. Samplers were located at 10 residential sites, a regulatory air monitoring
station, and a site located at the centroid of the census tract in which the regulatory station was located. For residential
sites, sampler placement locations (e. g., covered porch vs. house eaves) had no effect on concentration with the exception
of methyl tertiary-butyl ether (MTBE). Relatively high correlations (Pearson r > 0.8) were found between toluene, ethylbenzene, and o,m,p-xylenes suggesting petroleum-related influence. Chloroform was not correlated with these species or benzene (Pearson r < 0.35) suggesting a different source influence, possibly from process-related activities. As shown in other spatial studies,
wind direction relative to source location had an effect on VOC concentrations. 相似文献
3.
Jackson MM 《Environmental monitoring and assessment》2006,116(1-3):363-382
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. 相似文献
4.
吹扫捕集-GC/MS-SIM法测定海水中挥发性有机污染物 总被引:2,自引:0,他引:2
采用吹扫捕集 -GC/MS -SIM法测定水中挥发性有机物 ,具有定量准确、操作简便等特点 ,检测限可达ng/L级 ,适合环境水中低浓度挥发性有机物的测定。测定实际海水样品 ,其浓度范围在 0 4ng/L~ 1 0 0 0ng/L之间。 相似文献
5.
吹扫—捕集/气相色谱法测定水中挥发性有机物 总被引:3,自引:0,他引:3
为提高样品分析效率,研究并建立了吹扫-捕集/气相色谱/氢火焰检测器联用同时测定水中1,2-二氯乙烷、苯、甲苯、氯苯、乙苯、对-二甲苯、间-二甲苯、苯乙烯、邻-二甲苯、异丙苯、1,4-二氯苯、1,2-二氯苯、硝基苯、1,3,5-三氯苯、1,2,4-三氯苯、1,2,3-三氯苯、六氯丁二烯17种挥发性有机物的分析方法。结果表明,当进样体积为25.0ml时,最低检出限为0.0034-0.1088μg/L,相对标准偏差为1.8%~6.4%,加标平均回收率为97.6%-105.8%。该方法可快速、简便、准确、高灵敏度的测定水中17种挥发性有机物,并适用于饮用水和地表水中挥发性有机物的测定。 相似文献
6.
预冷浓缩系统与气相色谱——质谱法测定室内空气中挥发性有机物 总被引:1,自引:0,他引:1
针对室内空气挥发性有机物测定方法的不足,本文采用预冷浓缩系统和气相色谱,质谱联用。建立了测定室内空气中39种挥发性有机物的分析方法,该方法采用苏码罐采样,经液氮预冷冻浓缩后,用心城由检测。该方法灵敏度高,操作简便、重现性好、准确度高,适用于室内空气中挥发性有机物的测定。 相似文献
7.
采用吹扫捕集—气相色谱—质谱联用技术分析水中的24种挥发性有机物。通过优化分析条件,改善了各组份的分离效果,节省了分析时间,得到各组份检测限为0.001-0.099μg/L,相对标准偏差为2.3%-5.6%,加标回收率为91.2%-107.6%,方法具有较好的精密度、准确度和低检测限。同时对漳州市饮用水源中的24种挥发性有机物进行监测分析,结果均低于检测限。 相似文献
8.
This study aimed to locate VOC emission sources and characterized their emitted VOCs. To avoid interferences from vehicle exhaust, all sampling sites were positioned inside the refinery. Samples, taken with canisters, were analyzed by GC–MS according to TO-14 method. The survey period extended from Febrary 2004 to December 2004, sampling twice per season. To interpret a large number of VOC data was a rather difficult task. This study featured using ordinary application software, Excel and Surfer, instead of expensive one like GIS, to overcome it. Consolidating data into a database on Excel facilitated retrieval, statistical analysis and presentation in the form of either table or graph. The cross analysis of the data suggested that the abundant VOCs were alkanes, alkenes, aromatics and cyclic HCs. Emission sources were located by mapping the concentration distribution of these four types of VOCs in terms of contour maps on Surfer. During eight surveys, five emission sources were located and their VOCs were characterized. 相似文献