兰州市空气PM_(2.5)中十种金属和类金属浓度的季节性变化

Cross-section Study on Seasonal Variations of PM_(2.5) Concentrations for Ten Metal and Melloids in Air of Lanzhou City

目的通过对兰州市空气中PM_(2.5)监测成分进行研究分析,发现主要污染成分和污染季节,为相关部门制定防控措施提供参考依据。方法 2015年分别在兰州市城关区和西固区2个监测点采集PM_(2.5)颗粒物样品,检测PM_(2.5)及10种元素的含量,并分析季节性趋势。结果城关区和西固区PM_(2.5)颗粒物中铅、镉及锰的含量有统计学差异,且城关区高于西固区;城关区四个季节的PM_(2.5)的含量有统计学差异(χ~2=18.406,P<0.001),城关区春季PM_(2.5)的含量最高,为0.12 mg/m^3,秋季最低,为0.07 mg/m^3;西固区四个季节的PM_(2.5)的含量有统计学差异(χ~2=30.0,P<0.001),西固区冬季PM_(2.5)的含量最高,为0.11 mg/m^3,夏季最低,为0.05 mg/m^3。结论 2015年兰州市城关区和西固区PM_(2.5)颗粒物及其元素污染水平有差别,需要重视不同季节大气污染,制定相应的污染防控措施。

Objective To understand the concentrations of ten metal and metalloids in PM_(2.5)of air in Lanzhou city,and to find out the main pollutants and heavy polluted seasons,thus to provide a basic data for air pollution control. Methods Chengguan District and Xigu District of Lanzhou were selected as the surveillance sites. The concentration of PM_(2.5)and ten metal and melloids in air samples were determined in 2015. Results The concentration of Plumbum( Pb),Cadmium( Cd) and Manganese( Mn) of PM_(2.5)in Chengguan district were higher than those in Xigu district,and the seasonal variation of these three metals were significant in Chengguan district( χ~2= 18. 406,P < 0. 001) and Xigu district( χ~2= 30. 0,P < 0. 001). For instance,the concentration of PM_(2.5)in Chengguan district in the Spring was the highest( 0. 12 ng/m^3),and in Xigu district in the Winter was the highest( 0. 11 ng/m^3). Conclusions There were obvious seasonal trend on concentration of several ten metal and melloid in PM_(2.5)in 2015. Hence, the measure on prevention of air pollution should comply with the prevalence characteristics of air pollution in different seasons.