Charateristics of n-alkanes in urban air and two-stroke motorcycle exhaust

• Main Authors: Young, Li-Hao, 楊禮豪
• Other Authors: Chiu-Sen Wang
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/73726206706663901665

碩士 === 國立臺灣大學 === 環境衛生研究所 === 86 === ABSTRACT The objective of this study is to determine the bulk characteristics of n-alkanes in the carbon number range of C15∼C36 in urban air and two-stro ke motorcycle exhaust. The vapor/particle distribution of n-alkanes in urban air was also examined. The bulk characteristics of n-alkanes were used in ide ntifying various sources of fine particles. We used a Model 310 Universal Air Sampler (MSP Corporation) to collect fine particulate matter (≦2.5 micromete r) on quartz fiber filters and to adsorb vapor-phase compounds on solid sorben ts placed downstream of the filter. The sorbents consisted of XAD-2 sandwiche d between two layers of polyurethane foam（PUF）. The sampler was placed on t he rooftop, 15.7m above the street level, at Chung Shan Elementary School in t he Taipei City. Samples were collected once every 10 days. The sampler ran 1 0 minutes in each quarter of an hour at a flow rate of 285 L/min during Septem ber 10, 1997 to March 24, 1998. A two-stroke 50c.c. motorcycle engine was tes ted under constant speeds on a dynamometer. Motorcycle exhaust samples were c ollected downstream of a dilution tunnel by using quartz filter follwed by XAD -16 solid sorbent. The n-alkanes collected on filters and solid sorbent were extracted with CH2Cl2 in a Soxhlet extraction apparatus. Qualitative and quan titative analysis of the n-alkanes were carried out by GC/FID. The results sh ow that the ambient concentrations of total particulate and vapor n-alkanes ra nged from 67 ~ 586 ng/m3 and 401 ~ 1003 ng/m3, respectively. The Carbon Prefe rence Index ( CPI ) of n-alkanes obtained from the motorcycle exhaust samples were around 1 and the Carbon number maximum ( CMAX ) at C19、C24 or C25. The data on CPI and CMAX of ambient samples indicate that emssions from fossil fue l combustions are the major sources of n-alkanes in the Taipei aerosol.Keyword s：fine particle, two-stroke motorcycle exhaust, semivolatile organic matter, n-alkanes, vapor / particle distribution