阴霾天气PM_(10)的微观特征及生物活性研究

利用高分辨率场发射扫描电镜(FESEM)、图像分析技术(IA),对北京市2004年12月一次严重的阴霾天气条件下采集的PM10(指空气动力学直径小于10μm的颗粒物)的微观形貌、粒度分布、主要颗粒物类型进行了分析,并运用质粒DNA评价法对阴霾和非阴霾天气条件下的PM10样品的生物活性进行了对比研究。结果表明,阴霾天气时PM10样品中以粒度较小的烟尘及其集合体为主,且多呈湿状,含有较多的二次颗粒物,并发现了残余的有机液滴颗粒。质粒DNA实验的结果显示,阴霾天气PM10样品的水溶和全样样品的TD20值(造成20%DNA破坏时所需要的样品剂量)分别为93μg.ml-1和50μg.ml-1,而同一月份非阴霾天气条件下PM10样品的水溶和全样样品的TD20值分别为200μg.ml-1和160μg.ml-1,表明阴霾天气PM10样品比非阴霾天气样品具较强的生物活性,即对人体健康存在着潜在的危害。且无论是阴霾还是非阴霾天气条件下的PM10的全样样品均较水溶样品具更大的生物活性。

Microscopic Characteristics and Bioactivity of PM10 Collected in Haze Weather

High Resolution Field Emission Scanning Electron Microscopy(FESEM) and image analysis technology(IA) were employed to investigate the microscopic morphology and size distributions of PM10 collected during a serious haze episode in December 2004.The plasmid DNA scission assay was used to study the bioactivity of PM10 in haze and non-haze episodes.The results showed that the haze PM10 is dominated by soot and soot aggregates,which are finer and mostly in wet state,with a significant amount of secondary particles.The residual organic drops are also found in the haze PM10.The plasmid DNA scission assay indicates that the TD20s(the dosage of PM10 that caused 20% DNA damage) of the whole sample and corresponding soluble fraction of the haze PM10 are 50 μg·ml-1 and 93 μg·ml-1,respectively,and the TD20s of whole sample and corresponding soluble fraction of the non-haze PM10 are 160 μg·ml-1 and 200 μg·ml-1.The results showed that bioactivity of the haze PM10 is stronger than that of the non-haze sample,implying that PM10 in haze weather may do potential harm to human health.In addition,bioactivity of the whole sample is stronger than that of soluble fractions of PM10 both in haze and non-haze weather.