沙尘事件对兰州河谷大气环境PM_(10)的影响

Impact of Dust Events on Air PM_(10) Concentration in the Lanzhou Valley

利用1999—2001年兰州河谷大气中空气污染物的监测数据,结合河西地区沙尘事件频次,分析了兰州河谷大气环境PM10含量的季节变化特征及其成因。结果表明,源于河西地区的沙尘暴对兰州市空气中PM10含量有重要影响,PM10浓度在冬春季较高,在夏季较低。1985—2001年16a来河西走廊中东部沙尘事件年均约为37.6d,兰州河谷年均沙尘事件约为24.4d,两者表现出显著的相关性(R=0.67,P=0.003)。2001年兰州河谷1h平均沙尘PM10浓度统计分析显示:PM10含量大于1.0mg.m-3的峰值,主要由河西地区沙尘暴过程引起,而PM10含量0.5～1.0mg.m-3之间的峰值,主要由工业污染物SO2、NOx及颗粒物的排放引起。要长期有效地改善兰州市大气环境质量,不仅要科学地制定本地污染物的减排措施,还要考虑周围地区生态环境的建设。

Seasonal variation of PM10 and the causes of the PM10 long-term trend in Lanzhou valley were studied using the air pollutant monitoring data during 1999—2001 in Lanzhou and the statistical data of dust storm frequency in Hexi Corridor.Results indicated that the dust storm events in Hexi Corridor area had an important influence on PM10 concentration of Lanzhou,and the PM10 concentration showed higher value in Spring and Winter while exhibited lower value in Summer.Sand-dust frequency monitoring data during 1985—2001 demonstrated that the annual average frequentcy of dust events in the sixteen years in middle-east part of the Hexi Corridor was about 37.6 days,and the annual average days of the dust events in the sixteen years in the Lanzhou Valley was about 24.4 days,and there was a significant correlation between them（R=0.67,P=0.003）.Statistical analysis of hourly mean PM10 concentration in 2001 in the Lanzhou Valley showed that PM10 peak values more than 1.0 mg·m-3 were mostly caused by the process of dust storm in Hexi Corridor area,however,PM10 peak values between 0.5—1.0 mg·m-3 were mainly caused by the emission of industrial pollutant SO2,NOx and some other particles.In order to effectively improve the air quality in Lanzhou for ever,it is advisable to not only establish effective control strategies of emission but also improve surrounding ecological environment.