摘要
综合应用小波分析和Mann-Kendall非参数检验方法,对上海市近12aPM10、SO2和NO2逐日空气污染指数序列进行分析,揭示了空气污染变化的多尺度特征、变化趋势和突变特性,以深入了解上海市空气质量状况。结果表明:PM10、SO2和NO2污染序列呈现多尺度的变化特征,具有1 000d和300d左右的中、小时间尺度周期。在小尺度上,各序列具有300d左右的主周期和30d左右的次周期。空气污染具有"冬重夏轻"的特征,冬季和春季是污染比较严重的时段;2007年夏季以来,空气质量总体趋于好转。近12a来各序列均呈显著的减少趋势;PM10序列突变开始于2006年7月3日前后,SO2于2010年3月21日前后,NO2则于2006年4月18日前后;突变后,各序列基本均呈显著的下降趋势。最后,提出了未来改善上海市空气质量的相关建议。
The multiple scale characteristics of air pollution index change in Shanghai City, its trends and mutation features were examined via Wavelet analysis and Mann-Kendall nonparametric test method based on the daily air pollution index sequence of PM10, SO2 and NO2 over a time period of recent 12 years. Firstly, continuous wavelet transform was employed to investigate the air pollution change, which revealed the multiple scale characteristics of the variance of air pollution sequences of PM10 ,SO2 and NO2.Wavelet variance analysis indicated that, the three air pollution sequences had different periodicity at medium and short time scales.The sequences had a medium scale period of around 1000 days and a short scale period of 300 days,while at small time scales,the sequences had primary peroids of around 300 days and secondary periods of around 30 days.The periodic analysis results at 300 days and 30 days time scales indicated that air pollution was heavier in summer and lighter in winter. Additionally,the results at 30 days time scale showed winter and spring were the seasons when pollution was much more significantly affected by the weather and season factors,and air quality of Shanghai tended to improve in recent years.Wavelet analysis The sequence mutation of PM10 pollution began from July 3,2006, SO2 from March 21,2010, and NO2 from April 18,2006. Thereafter, the three sequences showed significant downward trend. Although there were local fluctuations,the air quality tended to get better.PM10and NO2 pollution reduced since the summer of 2006,and SOz pollution reduced after the spring of 2010. Though SOz pollution was the most serious in 2007, but it later reduced year by year.Before 2010,SO2 sequence showed a significant upward trend over a long period of time,indicating that the short-term decline might be just normal fluctuation in the overall upward trend for a long time, and rise and fall of the sequence repeatedly formed the characteristics of multiple time scales.Both the wavelet and Mann-Kendall methods had their advantages and drawbacks, and the analysis results of the two methods could verify and complement each other to get more accurate conclusion,providing reference for the urban atmospheric environment monitoring and protection. High- speed economic developments of Shanghai brought tremendous environmental pressure. With the rapid growth of automotive vehicles,the increased road dust density and exhaust poisnous emissions became the source of air pollutants of the urban areas in Shanghai.Despite many measures taken and efforts made on air pollution control by the Shanghai administration, air pollution in Shanghai remains a problem to address.Finally,proposals were put forward to improve the urban air quality in Shanghai in the future.
出处
《长江流域资源与环境》
CAS
CSSCI
CSCD
北大核心
2013年第12期1614-1620,共7页
Resources and Environment in the Yangtze Basin
基金
国家自然科学基金项目(41202243
41301646)
