摘要
利用2001年1月～2007年12月兰州市空气质量日报数据,结合时间尺度分离法,分析研究了兰州市PM10污染的年、季变化特征、年变化趋势及其成因.结果表明,2001年以来兰州市PM10污染有所减轻,年日均PM10浓度由2001年的236μg.m-3下降为2007年的127μg.m-3,空气质量为优、良的天数增加了1.3倍,但年平均PM10浓度仍超过国家二级标准,超标率为25%;PM10污染存在明显的季节变化,冬半年的11月、12月和1～4月PM10浓度较高,月平均最大值和次大值分别出现在12月(271μg.m-3)和3月(245μg.m-3),5～10月PM10浓度较低,基本维持在150μg.m-3以下;61.2%的中度污染和50.6%的重度污染发生在冬季,67.4%的优良天数出现在夏季和秋季;2001～2007年,兰州市PM10浓度每年下降12.6%与兰州市烟、粉尘年排放量变化趋势一致;由于沙尘、浮尘天气造成的自然尘排放量的年际变化对PM10浓度年际变化趋势的贡献约为21%,而局地气象条件的扰动对PM10浓度年际变化的影响很小.近年来兰州市PM10污染状况的改善主要是由本地污染物排放量的减少造成的,同时也受沙尘、浮尘天气年际变化的影响,要长期有效地改善兰州市大气环境质量,不仅要制定科学合理的本地减排措施,还应考虑周围生态环境的改善.
Seasonal characteristics,annual variations and trend of PM10 and the causes of the PM10 long-term trend in Lanzhou were studied for the period of 2001-2007 using daily air pollution index（API） data and detrending technique.Results indicate that air quality in Lanzhou has been improved since 2001.The annual averaged PM10 concentration decreased from 236 μg·m-3 in 2001 to 127 μg·m-3 in 2007 and the number of days satisfying the Chinese Grade Ⅰ and Ⅱ air quality standard increased 2.3 times as 2001,but there still have 25% days exceeding the national Grade Ⅱ air quality standard.Monthly mean PM10 concentration undergoes a seasonal change characterized by higher values in November,December and January to March.The maximum monthly average PM10 concentrations appear in December（271 μg·m^-3） followed by March（245 μg·m^-3）while it is low during summer months（May to October） with monthly average PM10 concentrations below 150 μg·m^-3.61.2% of moderate pollution and 50.6% of serious pollution .days occurred in winter and 67.4% of Grade Ⅰ and Ⅱ days occurred in summer and autumn.Analyses show that annual mean PM10 concentrations decreased at a rate of 12.6% over the past 7 years which correlates well with the reductions in anthropogenic dust emissions.The occurrence of blowing dust and floating dust can modulate the overall trend of PM10,which explains about 21% of the inter-annual variations of PM_10 during 2001-2007.The changes of local meteorological conditions have little effect on the overall trend of PM10 concentrations.The improvement of air quality in Lanzhou is mainly due to the reduction of local emissions,with contributions from the variation of natural dust emissions due to annual variations of blowing and floating dust events.To further improvement of the air quality in Lanzhou,it is advisable to not only implement effective emission control strategies but also improve surrounding ecological environment.
出处
《环境科学》
EI
CAS
CSCD
北大核心
2010年第1期22-28,共7页
Environmental Science
基金
中国科学院"引进国外杰出人才"项目
中国科学院寒区旱区环境与工程研究所"人才基金"项目
作者简介
余晔（1973～），女，博士，研究员，主要研究方向为城市和区域大气环境，E-mail：yyu@lzb．ac．cn
