Browsing by Author "Hung, IF"

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Atmospheric lead concentration distribution in Northern Taiwan
(2003-08-01)
Lu, HC
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Tsai, CJ
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Hung, IF
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環境工程研究所
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Institute of Environmental Engineering
Atmospheric lead concentrations were measured randomly, approximately once per week, at five traffic sites in northern Taiwan from September 1994 to May 1995. Three types,of theoretical distributions, lognormal, Weibull and gamma were selected to fit the frequency distribution of the measured lead concentration. Four goodness-of-fit criteria were used to judge which theoretical distribution is the most appropriate to represent the frequency distributions of atmospheric lead. The results show that atmospheric lead concentrations in total suspended particulates fit the lognormal distribution reasonably well in northern Taiwan. The intervals of fitted theoretical cumulative frequency distributions (CFDs) can successfully contain the measured data when the population mean is estimated with a 95% confidence interval. In addition, atmospheric lead concentration exceeding a critical concentration is also predicted from the fitted theoretical CFDs. (C) 2003 Elsevier Science Ltd. All rights reserved.
Concentration profiles of acidic and basic air pollutants around an industrial park of Taiwan
(2004-01-01)
Tsai, CJ
;
Aggarwal, SG
;
Chang, CT
;
Hung, IF
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環境工程研究所
The results of spatial and temporal distribution of acidic and basic air pollutants in ambient air around Hsinchu Science-Based Industrial Park (SBIP), Taiwan during August 2000 to October 2001 are presented. The sampling was performed on 13 different sites around the SBIP for 12 hrs each every month, and a total of 195 samples were collected. The effect of geographical and meteorological conditions, and production volume of the SBIP on the variation of pollutant's concentration was investigated. The spatial distribution shows that comparatively higher concentration of pollutants was found on the sites, which are either low in altitude such as the WS (west-southern) part of SBIP, in the downwind location or close to the factories. In case the wind velocity was low, i.e. below 2 m s(-1), the concentration of pollutant tended to increase and became uniformly distributed around the science park. The temporal distribution shows a decrease in ambient concentration of pollutants from February to June 2001, mainly due to the decline in the production volume of the SBIP in this period. During the whole period of investigation, the concentration of most of the species ( except HF) was found to be lower than the factory-surrounding air quality standard of Taiwan, but in some cases it was higher than the AALG.
Sampling time effect on 2,4-Toluene diisocyanate concentration by using different samplers
(2006)
Tsai, CJ
;
Lin, HC
;
Lin, KY
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Shih, TS
;
Chang, KC
In order to understand the sampling time effect on the 2,4-TDI (Toluene diisocyanate) concentrations, laboratory and field tests were conducted in this study. An ADS (annular denuder sampler) and two OFFCs (open face filter holders) with different filters were tested for 1 to 120 minutes in the laboratory using 2,4-TDI gas. In the field study, the standard sampling method, the dual filter the triple filter and annular denuder systems were used at two workplaces to study the change of 2,4-TDI concentrations with sampling time from 15 to 60 minutes. The test results in both laboratory and field studies show that the sampling time influences the sampled TDI concentration considerably which may be due to reaction of TDI with water vapor and polyo in the sampling process. It is evident that as sampling time increases the TDI concentration decreases very significantly.
Simultaneous sampling of gas- and aerosol-phase TDI with a triple filter system
(2003-10-01)
Tsai, CJ
;
Cheng, KC
;
Aggarwal, SG
;
Shih, TS
;
Hung, IF
A new triple filter system sampler/model is proposed for the precise and accurate simultaneous sampling and determination of gas- and aerosol-phase 2,4-toluene diisocyanate (TDI). The system consists of two front Teflon filters for sampling aerosol-phase TDI and a final coated glass fiber filter to collect gas-phase TDI. The aerosol-phase TDI is collected on the first Teflon filter, while the second Teflon filter is used to estimate gaseous TDI adsorbed by the first. According to the gas adsorption test of two Teflon filters in series, the TDI gas adsorption fraction of the two filters is almost the same. Results of the evaporation test using pure TDI aerosols collected on the Teflon filter show that significant evaporation of the compound does not occur during sampling. These two findings allow the use of a model to estimate accurate gas- and aerosol-phase TDI, concentrations. The comparison test with an annular denuder shows that the triple filter system can minimize the TDI sampling bias between the dual filter and the annular denuder systems.