| 沙尘天气对生物气溶胶中总微生物浓度及粒径分布的影响 |
| 摘要点击 3265 全文点击 1287 投稿时间：2017-01-03 修订日期：2017-03-07 |
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| 中文关键词 沙尘 生物气溶胶 微生物浓度 粒径分布 PM10 |
| 英文关键词 dust bioaerosols microbial concentration size distribution PM10 |
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| 中文摘要 |
| 为了解沙尘对生物气溶胶中微生物的影响，于2015年3~4月间分别在兰州和青岛沙尘期间运用分级生物气溶胶采样器连续采集了生物气溶胶样品，并利用DAPI染色-荧光显微镜计数方法测定了总微生物浓度. 结果表明，沙尘发生时生物气溶胶中总微生物浓度显著增加（P<0.05）. 兰州和青岛总微生物浓度晴天背景均值分别为5.61×105 cells·m-3和2.08×105 cells·m-3，沙尘时平均浓度分别是晴天的14.8倍和6.42倍. 晴天时兰州和青岛两地样品微生物粒径分布均呈双峰分布，最高峰值均出现在>7.0 μm的粒径上，最低值均出现在4.7~7.0 μm的粒径上，浓度次高峰值分别出现在3.3~4.7 μm的粒径上和1.1~2.1 μm的粒径上. 沙尘时粒径分布均发生明显变化，兰州仍呈现双峰分布，但其中一个峰值从>7.0 μm移动到1.1~2.1 μm；而青岛粒径由双峰分布变为粗粒径偏态分布. 兰州和青岛沙尘前微生物负荷的背景值分别是2224 cells·μg-1和1550 cells·μg-1，而沙尘发生时，颗粒物的微生物负荷均大幅增加，最高值分别达26442 cells·μg-1和10250 cells·μg-1，这说明沙尘天气发生时，微生物浓度的增加不仅仅是因为空气中颗粒物的增加，而是因为长距离传输的沙尘颗粒携带有大量外源微生物. |
| 英文摘要 |
| In order to study the influence of dust events on the airborne microbes in atmospheric bioaerosols, bioaerosol samples were continuously collected from March to April 2015 during two dust events using size-fractionated bioaerosol samplers in Lanzhou and Qingdao. The concentration of airborne microbes were measured using an epifluorescence microscope after staining with DAPI (4',6-diamidino-2-phenylindole). The results showed that the concentration of airborne microbes increased significantly during the period of dust (P<0.05). The average concentrations of airborne microbes on sunny days were 5.61×105 cells·m-3 and 2.08×105 cells·m-3 in Lanzhou and Qingdao, respectively, whereas the mean concentrations on dusty days were 14.8 times and 6.42 times those on sunny days, respectively. The concentration of airborne microbes presented a bimodal size distribution on sunny days in Lanzhou and Qingdao, with a peak at>7.0 μm and the lowest values ranging from 4.7 μm to 7.0 μm. However, the second peak appeared at 3.3-4.7 μm and 1.1-2.1 μm in Lanzhou and Qingdao, respectively. The size distribution of airborne microbes changed during the dust period. The size distribution of microbes still presented a bimodal distribution in Lanzhou; however, one peak shifted from>7.0 μm to 1.1-2.1 μm. The size distribution in Qingdao changed from a bimodal distribution to a skewed distribution with the predominant fraction in coarse mode. The background values of microbial load in PM10 before the dust were 2224 cells·μg-1 and 1550 cells·μg-1 in Lanzhou and Qingdao, respectively, and the highest value of such increased significantly to 26442 cells·μg-1 and 10250 cells·μg-1 during the dust events, respectively. This demonstrated that the high concentration of microbes in the dust events resulted not only from increased atmospheric particles but also from dust source and transportation path along with long-range transported dust particles. |
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