北京市某地区冬季大气细颗粒物和超细颗粒物污染水平及影响因素分析

摘要

目的：研究北京市某地区冬季大气细颗粒物和超细颗粒物污染水平，并分析其影响因素。方法：以北京市某地区为监测点，对冬季大气中的细颗粒物和超细颗粒物进行连续实时监测，同时采集每日气象数据，采用Mann-Whitney U秩和检验对不同时期的大气颗粒物浓度进行比较，并对其可能的影响因素进行分析。结果：监测期间该地区的细颗粒物质量浓度平均值为（157．2±142．8）μg/m3，超细颗粒物的数浓度平均值为（25018±9309）个/cm3，其中雾霾天气时细颗粒物质量浓度和超细颗粒物数浓度分别为非雾霾天气时的2．91倍和1．27倍。监测点细颗粒物的平均浓度远高于附近北京市固定监测点的平均浓度，大气超细颗粒物的小时浓度均值变化趋势与上、下班高峰期相一致。燃放烟花爆竹可导致大气颗粒物浓度在短时间内迅速上升，但可在短时间内降低至正常水平。当风速较低、相对湿度较高时，大气颗粒物的浓度较高，且浓度变化具有一定的滞后性。结论：该地区大气细颗粒物和超细颗粒物的水平相对较高。交通、燃放烟花爆竹以及气象因素可能是影响该地区颗粒物浓度的几个主要因素，其中燃放烟花爆竹所导致的大气颗粒物浓度变化表现为瞬时性，气象因素的影响存在一定的滞后性。%Objective:To study the concentrations of fine particulate matters and ultrafine particles and influenced factors during winter in an area of Beijing .Methods:Real-time monitoring of particles ’ mass and number concentrations were conducted in an area of Beijing from February 7th to 27th , 2013.At the same time, the meteorological data were also collected from the Beijing meteorological website .Differences of the particles ’ mass and number concentrations during different periods were analyzed using Mann -Whitney U test.Meanwhile, the influenced factors were also analyzed .Results: The mean concentra-tions of fine particulate matters and ultrafine particles were ( 157.2 ±142.8 ) μg/m3 and (25 018 ± 9 309) particles/cm3, respectively.The particles’ number and mass concentrations in haze days were 1.27 times and 2.91 times higher than those in non-haze days, respectively.The mass concentrations of fine particulate matters in the self-monitoring site were higher than those in the nearest central monitoring sites, and the hourly-average concentrations of particles were significantly consistent with those at the commuter times.Meanwhile, the setting off of fireworks/firecrackers during the Spring Festival could lead to short-term increases of the particles ’ number and mass concentrations .When the wind speed was low and the related humidity was high , the concentrations of particulate matters were relatively high , and the mass concentrations of fine particulate matters were lagged about 1-2 d.Conclusion: The level of the particulate matters in this area was high .Heavy traffic , setting off of fireworks/firecrackers and meteoro-logical factors may be some of the main factors affecting the concentrations of the particulate matters in this area.Among those factors, the effect of setting off of fireworks/firecrackers didn’t last long and the effect of the meteorological factors had a hysteresis effect .