DSpace collection: 期刊論文

The impact of ground-level fireworks (13 km long) display on the air quality during the traditional Yanshui Lantern Festival in Taiwan

Tue, 27 Mar 2012 09:05:22 GMT

title: The impact of ground-level fireworks (13 km long) display on the air quality during the traditional Yanshui Lantern Festival in Taiwan abstract: In this study, the concentrations of CO, non-methane hydrocarbons, NO(X), SO(2), benzene, toluene, ethylbenzene, xylene (BTEX), PM(10), and PM(2.5) were continuously monitored before and after the fireworks display during the traditional Lantern Festival from March 2-7, 2007 in Yanshui Town, Taiwan. Major roads in Yanshui Town were surrounded by fireworks 13 km in length, with the display lasting for 45 min. More than 200 small firecracker towers popped up randomly in town, resulting in exceedingly inhomogeneous air quality until the end of display at 03:00 the next day, March 5. During the fireworks display, the hourly concentration of PM(10) and PM(2.5) at Yanshui Primary School reached about 429 and 250 mu g m (-aEuro parts per thousand 3), respectively, which is 10 times the normal level, and 6 s values even went as high as 1,046 and 842 mu g m (-aEuro parts per thousand 3), respectively. Similarly, BTEX concentration went up to about five to 10 times its normal value during the fireworks display. As indicated by the distribution of submicron particle sizes, the number of particles with a diameter less than 100 nm increased abruptly during the event period. Metal components with concentrations of more than 10 times higher than the normal value at Yanshui Primary School were Sr, K, Ba, Pb, Al, Mg, and Cu, in sequence. Among water-soluble ions, the content of K (+) , Mg(2 +) , and Cl (-aEuro parts per thousand) increased the most, all of which were related to the materials used in the fireworks. The results of this study indicate that fireworks can cause an abrupt increase in the concentration of trace substances in the air within a short period. Although the risks of these trace substances on public health remain to be further assessed, the study results can be utilized in the management of folk events.

The enhancement of PM(2.5) mass and water-soluble ions of biosmoke transported from Southeast Asia over the Mountain Lulin site in Taiwan

Tue, 27 Mar 2012 09:05:20 GMT

title: The enhancement of PM(2.5) mass and water-soluble ions of biosmoke transported from Southeast Asia over the Mountain Lulin site in Taiwan abstract: Biomass burning (BB) in Southeast Asia (Indochina and southern China) occurs frequently in March and April every year. The burning plume is ordinarily transported eastward by the prevailing westerly, further affecting downstream air quality in East Asia. In this study, atmospheric aerosols were collected at the downstream Lulin Atmospheric Background Station (LABS, 2862 m a.s.l., central Taiwan) from April 2003 to April 2009. Results show that monthly means of PM(2.5) were highest during the BB period, especially in March. The PM(2.5) mean for BB activity was 17.5 mu g m(-3), while the daily PM(2.5) mean can sometimes be above 40 mu g m(-3). The background PM(2.5) level in free troposphere of the West Pacific was at 3.7 +/- 1.8 mu g m(-3). This mean is roughly the same regardless of the air masses moving from China, Pacific Ocean, and South China Sea toward LABS. In addition, the highest PM(2.5) level occurred in 2004, making it the most active year of BB for the whole observation period. Greater amounts of nitrate and potassium ions were observed in the PM(2.5) collected during the BB period compared to the non-BB (NBB) period. Linear regression analysis on PM(2.5) water-soluble ions shows a moderate correlation (R(2) = 0.59) between non-sea-salt potassium and nitrate ions during the BB period. Furthermore, for all trajectory source origins, ammonium ion had the best correlation (R(2) = 0.84) with non-sea-salt sulfate when the air masses were influenced by anthropogenic sources during the NBB period. The enhancement ratios of nitrate ion during the BB period could reach 6.7 and 9.7 relative to air masses from the BB source region and from the pristine area during the NBB period, respectively. During the study period, ammonia gas was found to be insufficient to neutralize sulfuric and nitric gases. Therefore, most aerosols were more acidic than basic. Our long-term observation of atmospheric aerosols with inter-annual variability is valuable in providing data for verifying BB source inventory and model performance in East Asia. (C) 2011 Elsevier Ltd. All rights reserved.

Removal of C(3)F(8) Via the Combination of Non-Thermal Plasma, Adsorption and Catalysis

Tue, 27 Mar 2012 09:05:17 GMT

title: Removal of C(3)F(8) Via the Combination of Non-Thermal Plasma, Adsorption and Catalysis abstract: The feasibility of C(3)F(8) abatement via combining nonthermal plasma with adsorption and/or catalysis is investigated in this study. In terms of the simultaneous combination of plasma, adsorption and catalysis (CPAC), three different configurations including A/C layer (adsorbent layer prior to catalyst layer), C/A layer (catalyst layer prior to adsorbent layer) and A/C mixture (adsorbent and catalyst are mechanically mixed) are adopted. For all the experimental tests conducted in this study, the gas stream consists of 500 ppm C(3)F(8), 2% O(2), and balanced N(2). The experimental results indicate that C(3)F(8) removal efficiencies depend on what kind of packing material is adopted (adsorbent, catalyst or both) and how the material is packed within the plasma reactor. The removal efficiencies obtained with different reactors are in the order as: CPAC (A/C layer; AC mixture) > CPA (plasma with adsorbent alone) > CPC (plasma with catalyst alone) > CPAC (C/A layer). The indentified products after treatment include CO(2), CO, N(2)O and CF(4). The formation of C(2)F(6) is not observed in this study, which is encouraging since the global warming potential of C(2)F(6) is actually higher than that of C(3)F(8).

Reduction of dioxin emission by a multi-layer reactor with bead-shaped activated carbon in simulated gas stream and real flue gas of a sinter plant

Tue, 27 Mar 2012 09:05:11 GMT

title: Reduction of dioxin emission by a multi-layer reactor with bead-shaped activated carbon in simulated gas stream and real flue gas of a sinter plant abstract: A laboratory-scale multi-layer system was developed for the adsorption of PCDD/Fs from gas streams at various operating conditions, including gas flow rate, operating temperature and water vapor content. Excellent PCDD/F removal efficiency (>99.99%) was achieved with the multi-layer design with bead-shaped activated carbons (BACs). The PCDD/F removal efficiency achieved with the first layer adsorption bed decreased as the gas flow rate was increased due to the decrease of the gas retention time. The PCDD/F concentrations measured at the outlet of the third layer adsorption bed were all lower than 0.1 ng I-TEQ Nm(-3). The PCDD/Fs desorbed from BAC were mainly lowly chlorinated congeners and the PCDD/F outlet concentrations increased as the operating temperature was increased. In addition, the results of pilot-scale experiment (real flue gases of an iron ore sintering plant) indicated that as the gas flow rate was controlled at 15 slpm, the removal efficiencies of PCDD/F congeners achieved with the multi-layer reactor with BAC were better than that in higher gas flow rate condition (20 slpm). Overall, the lab-scale and pilot-scale experiments indicated that PCDD/F removal achieved by multi-layer reactor with BAC strongly depended on the flow rate of the gas stream to be treated. (C) 2010 Elsevier Ltd. All rights reserved.