西安市近地层空气离子与环境因子的关系研究

Relationship between Air Ion and Environmental Factors near Surface Layer in Xi’an

2009年8月至2010年7月在西安市16个采样点上开展了近地层空气离子浓度和温度、相对湿度、风速及可吸入颗粒物（PM1）0等环境因子的观测,研究了西安市空气离子时空分布的基本特征,并利用空气离子浓度值对西安市的空气质量进行了评价。另外,详细分析了近地层空气负离子浓度与温度、相对湿度和PM10等主要环境因子之间的相互关系。结果表明,西安市空气负离子的分布在时间与空间上均呈现出明显的不均匀性。在空间上,空气负离子浓度从市中心向郊区逐渐增大,市区平均浓度为200~300个/cm3,郊区达到500个/cm3以上;在时间上,空气负离子浓度在一年的夏季最高,冬季最低。研究结果也指出,空气负离子浓度与相对湿度和温度呈正相关关系,与PM10呈显著的负相关。最后,根据大气电离和扩散理论,探讨了上述环境因子对空气负离子浓度的影响机理。

Air ion concentration（AIC）near surface layer was measured at 16 sampling sites in Xi’an from August 2009 to July 2010,along with environmental factors such as temperature,relative humidity,wind speed and concentration of inhalable particulate matter（PM10）.Spatial-temporal distribution characteristics of AIC were studied,and then air quality was assessed based on the observed AIC.Relationships between the negative air ion concentration（NAIC） and environmental factors were analyzed in details.Results showed that both spatial and temporal distributions of NAIC are uneven.Spatially NAIC increases gradually from city center to suburb.Average NAIC ranges from 200 cm-3 to 300 cm-3 in urban,while more than 500 cm-3 in the suburb.Over a year NAIC is the highest in summer and lowest in winter.Results also indicated that there is positive correlation between NAIC and temperature and relative humidity,and negative correlation between NAIC and PM10 concentration.Influence mechanism of the aforementioned environmental factors was also discussed based on the theory of atmospheric ionization and diffusion.