Long-term Observation of Atmospheric Aerosols and their Component Changes in Downtown Tokyo
Long-term measurements of suspended paniculate matter (SPM,＜7 μm), PMfine (＜2.1 μm), and PMcoarse (2.1 to 7 μm) were obtained from an urban background site in downtown Tokyo, Japan for the period of 1994 to 2004 to evaluate the effects of emission reduction measures for motor-vehicle emissions. A remarkable PM mass decrease from 1996 forward, with all of the downward trend was seen in the PMfine fraction. Annual average PMcoarse was constant over the ten-year period. From 1996 to 2005, PMfine decreased at a rate of 2.09 μg m-3 yr-1 for PMfine mass. Most of this decrease in PMfine was attributable to decreases in elemental carbon (EC), and an average decrease ratio was 0.82 μg m-3 yr-1. This decrease is consistent with fleet penetration of engines and fuels that complied with a stringent Japanese emission reduction limit which began to take effect in 1994. Sulfate and nitrate concentrations did not decrease over this period. Evidence of Asian dust storm contributions was found in elevated PMcoarse and water-soluble calcium levels during the spring. A decline of concentration of chlorine ion in PMfine was large and an average decrease rate of peak concentration of chlorine ion in PMfine was 0.57μg m-3 yr-1. The reduction of chlorine ion concentration was discussed related with a limitation of waste substance incineration by Japanese dioxin law.
Japan Tokyo trends paniculate matter chemical composition elemental carbon
Hiroaki Minoura Katsuyuki Takahashi Judith C. Chow John G. Watson
Toyota Central R&D Labs., Inc., Nagakute, Aichi 480-2192, Japan National Institute for Environmental Studies, Tsukuba, Ibarati, Japan Desert Research Institute, Reno, Nevada, USA
国际会议
天津
英文
143-154
2007-07-17（万方平台首次上网日期，不代表论文的发表时间）