深圳市PM2.5 化学组成与时空分布特征

于2008-12-30～2009-12-25,在深圳市宝安区、罗湖区和盐田区各设置一个采样点采集大气细粒子PM2.5,分析了PM2.5中主要的水溶性离子组分、有机碳和元素碳,同时结合气象条件,对深圳市PM2.5的化学组成及时空分布特征进行了研究.结果表明,深圳市PM2.5污染总体上呈现西高东低的空间分布特点,但是SO24-和NH4+的空间差异不大,说明深圳PM2.5污染具有明显的区域传输特征.OC/EC值自西向东逐渐升高,说明深圳西部地区受一次源排放影响更为显著.受亚热带海洋性季风气候的影响,深圳市PM2.5总体污染程度表现为秋冬高、夏春低的特点,各主要组分的质量浓度变化也均有类似的特征.与2004年深圳的类似观测结果比较发现,该地区脱硫措施显著降低了PM2.5中硫酸盐浓度,而机动车尾气对PM2.5的贡献变得更加重要.

Characterising Seasonal Variation and Spatial Distribution of PM2.5 Species in Shenzhen

To investigate the effect of meteorological characteristics on PM_2.5 chemical composition and the spatial distribution of different PM_2.5 species in Shenzhen, 24-h PM_2.5 samples were collected every six days from December 2008 to December 2009. The sampling network included an industrial site at Baoan, an urban site at Luohu and a seaside site at Yantian. Water-soluble inorganic ions and carbonaceous material (organic carbon and elemental carbon) were analyzed. The industrial site showed a much higher concentration than that of other two sites of organic matter, elemental carbon and nitrate, which presented the obvious difference of local emissions. But for the concentration of sulfate and ammonium of three different sites nearly stayed at the same level and indicated that they were mainly influenced by regional transport. OC/EC had the characteristics of the industrial site2.5pollution was much more serious in winter than in summer. Compared with the results of the similar experiment in 2004, the concentration of sulfate in PM_2.5 has significantly declined because of the measures of reducing the emission of sulfer dioxide. But the pollution of vehicle emissions has become significant.