Fu-Tien Jeng

Precipitation chemistry in East Asia.

The chemical composition of precipitation in East Asia was analyzed on the basis of the results of cooperative monitoring performed during the period from 1992 to 1993. The wet deposition of soluble ions was characterized by two major factors; the geographical distribution of precursor production through natural and anthropogenic activities, and the meteorological conditions such as wind system and rainfall pattern due to the Asian monsoon. Although northeastern China had the largest anthropogenic emission source, precipitation with relatively high pH value was observed. At islands in the northern Pacific far from major anthropogenic emission sources, precipitation with relatively low pH value was observed. It was suggested that ammonia and calcium were constantly produced in the continent, and that the higher concentrations of these bases in the atmosphere were incorporated into precipitation elements and neutralized the acidity due to H2SO4 and HNO3 from fossil fuel combustion. The ratio of [nssCa2++NH4+]/[nssSO42−+NO3−] in precipitation was highest on the continent, moderate in the Korean Peninsula and the Japanese Islands, and lowest in the northern Pacific; in other words, this ratio decreased as the distance from the continent increased. In the central region of East Asia, which is affected by both continental cold, dry air masses and subtropical warm, humid air masses, the frequency distribution of pH of precipitation showed a bimodal pattern in which unimodal patterns of northern China and that of the Japanese Islands were superimposed. The wet deposition of nssSO42−, NO3−, nssCa2+, and NH4+ showed relatively small differences between the sites, while that of Na+ and Cl−, relatively large differences between the sites, reflecting the field of ionic concentration and amount of precipitation in East Asia.

Hygroscopic behavior of atmospheric aerosol in Taipei

Abstract Hygroscopic growth of particles of different sizes and the resultant size distribution changes were observed as a function of the relative humidity (RH). A particle generation device, RH module, and a Tandem Differential Mobility Analyzer system were set up to measure the particle size distributions under different RH conditions. Adopting Nafion as an RH adjusting module, the aerosol hygroscopic observations were successfully performed without the interference caused by blending sample stream with humidified air. The measured deliquescence humidity of model compounds, NaCl and (NH4)2SO4, agree with the theoretical values reported by other investigators. The particle growth factor is enhanced around the RH of 70%. In addition, particle size distribution behaves as two split groups of particles with the RH >76%. The average growth factors of hygroscopic ambient particles in Taiwan are similar to those reported elsewhere. There are several hygroscopic salt compositions in ambient aerosols, (NH4)2SO4 is the most abundant one. Observed particle deliquescence behaviors showed limited alternation of organics on particle growth at higher RH.

The virtual cyclone as a personal respirable sampler

Aerosol exposure via the inhalation route is a primary concern in occupational health. A researcher must perform aerosol size-selective sampling because respiratory deposition is dependent on aerosol size. The optimal sampling instrument is therefore the one that provides the most accurate measurement of the atmospheric dust component, thus showing the extent of a health hazard. However, the most commonly used respirable samplers today can only meet the 50% cut-off point and not the slope of the respirable convention prescribed by the American Conference of Governmental Industrial Hygienists (ACGIH), the Inter national Standard Organization (ISO), and the Comite European de Normalisa tion (CEN). These conventional cyclones are also found to be affected by the aerosol deposition and accumulation on the wall of the cyclone body, which leads to a significant decrease in aerosol penetration. In the present study, a miniature, compact, rugged virtual cyclone, which employs a nonimpact particle separation, was ...

Experimental Study on the Loading Characteristics of Needlefelt Filters with Micrometer-Sized Monodisperse Aerosols

In this work, three types of needlefelt filters, made of Polyester (PE), Ryton Sulfar (RS), and Polyaramid (PA), were tested to in- vestigate the aerosol loading characteristics of fabric filters when challenged with micrometer-sized monodisperse potassium sodium tartrate (PST) particles. A fibrous filter with packing density of 9%, thickness of 0.38 mm, and fiber diameter of 5.1 θ m was included for comparison. A vibrating orifice monodisperse aerosol generator was used to produce three different sizes (5, 10, and 20 θ m) of PST particles for aerosol loading experiment. An ultrasonic atomizing nozzle and a TSI constant output nebulizer were used to generate polydisperse PST particles for the aerosol penetration test. The aerosol penetration of submicrometer-sized particles through the filters was measured by using a Scanning Mobility Particle Sizer. An Aerodynamic Particle Sizer was used to measure the penetration fraction of aerosol particles larger than 0.8 θ m. The pressure drop across the filter was ...

Analysis of Motorcycle Exhaust Regular Testing Data—A Case Study of Taipei City

Abstract In Taiwan, a continuous increase in the number of motorcycles has made exhaust pollution one of the major emission sources of air pollutants. The regular testing program carried out by the Republic of China Environmental Protection Agency was designed to reduce air pollutant emissions by enhancing maintenance and repair. During the execution period, abundant testing results were accumulated to discuss pollutant emissions from motorcycles. Exhaust testing data of motorcycles in Taipei City from 1996 to 2005 were chosen as the basic data to survey changes in motorcycle exhaust. Effects of motorcycle age and mileage on exhaust pollution were studied. The introduction of advanced emission standards enhances the elimination of high-emitting motorcycles. The testing data indicate that the testing rate rose from approximately 50 to 70% and the failure rate changed from approximately 15 to 10%. The operation cycles of two-stroke motorcycles make them high-emitting vehicles. Concentrations of carbon monoxide and hydrocarbons are higher in two-stroke motorcycle exhaust than that in four-stroke motorcycles. In contrast, the concentration of carbon dioxide produced from complete oxidation processes is lower in exhaust from two-stroke motorcycles. Therefore, failure rates of two-stroke motorcycles are higher than those of four-stroke motorcycles and were also observed to deactivate more easily. On the basis of analytical results of testing data, we found that failure rates show a gradually increasing trend for motorcycles older than 3 yr or used for mileages greater than 10,000 km, and failure rates are highly correlated to the age/mileage of motorcycles. We reason that the accumulation of age or mileage means accumulating usage time of engines and emission control systems. Concentrations of pollutant emissions would increase because of engine wear and emission control system deactivation. After discussing changes of failure rates and pollutant emissions, some suggestions are proposed to improve the testing rate and effectiveness of regular testing.

Stability of Ionic Components in Precipitation Samples — A Case Study in Taipei

The changes in ionic contents were studied in acidic precipitation samples collected for precipitation events in Taipei, which is near the sea. The storage cases under investigation include filtration, refrigeration, and light. Thus the experimental design leads all precipitation samples collected in the same rain event stored under different conditions. They were then analyzed six times successively within two months to provide the information containing potential ionic composition change. The measured constituents are H+, K+, Na+, Ca2+, Mg2+, and Cl-. The comparison of measured ionic concentrations corresponding to different storage methods yield no significant difference. The increases of and decreases of with time were observed to be of similar magnitude, while the variation of pH values is significant. The presented study indicated the important role played by sample storage in determining the ionic composition of precipitation samples.

Technique for aerosol generation with controllable micrometer size distribution.

The purpose of this study is to develop an aerosol generating system that can produce particles of micrometer size in a convenient and efficient way. This system is comprised of an ultrasonic atomizer, potassium sodium tartrate tetrahydrate (PST) as solute and a program-controlled solute feeding unit with different PST concentrations. Both the aerosol concentration and size distribution pattern can be easily controlled and reproduced in the developed system. While the initial size of droplets generated from atomizer may remain unchanged, the size of residual dry aerosols was controlled by the solute concentration adjusted by the mixing ratio of solute and water. In addition, PST concentration could be alternatively adjusted in any cyclic way to provide particles with relatively mono-disperse, bimodal, varying size as well as skew distribution to meet requirements for various applications. The main advantage of the generating system is to generate particles of specific size distribution in order to simulate aerosols in ambient air or working places.

Influence of Bathing in a White Sulfur and Sodium Bicarbonate Hot Spring on Pulmonary Function in Normal Subjects

The short period effect of hot spring on pulmonary function of normal subjects is unclear. We attempt to investigate the pulmonary function changes during bathing in white sulfur springs (WSS), sodium bicarbonate hot spring (SBH) or tap water (TW). Fifty healthy people were enrolled and tested in 3 different types of water of WSS, SBH and TW for 20 minutes. Spirometry was used to evaluate the pulmonary function at the 0, 5, 10 15 and 20 minutes after the start of each bath. Among these three groups, the % predict value of forced expiratory capacity (FVC%), forced expiratory volume in the first second (FEV1%) and forced expiratory flow from 25% to 75% of the vital capacity (FEF(subscript 25-75%)) were not significantly different during WSS, SBH and TW at the 0, 5, 10, 15 and 20 minutes after the start of bathing. In WSS group, a significant increased FEV1% was found during WSS bathing at 10 minutes (89.43±11.50) of bathing compared to baseline (87.33±11.87) (p=0.023). FVC% at 10min (79.6±12.4; p=0.04) and at 20 min (80.0±13.1; p=0.03) were significant higher than baseline at 0 min (77.7±12.3). There was a significant increased %FEF(subscript 25-75%) at 10 min (109.7±20.4; p=0.040) and 20 min (110.9±23.2; p=0.037) compared with baseline (106.3±20.8) in SBH, and at 20 minutes (108.0±22.7; p=0.014) compared with baseline (105.2±21.9) in TW. These indicted that hot water aerosol inhalation to improve FEF(subscript 25-75%) reflected more patency in the small airway. FEF(subscript 25-75%) was not improved in WSS reflected aerosol of hot spring with H2S might to harmful for aerosol of hot spring with H2S. However, bath in hot spring improved FEV1 and FVC which reflected improved the respiratory effort. We concluded under good ventilation environment, white sulfur springs bathing in short period was not harmful but even beneficial to the pulmonary function.