塔克拉玛干沙漠腹地沙尘气溶胶质量浓度垂直分布特征

Vertical Distribution of Dust Aerosol Mass Concentration in Hinterland of the Taklimakan Desert

利用Grimm 1.108、Thermo RP 1 400a以及TSP等仪器于2009年1月至2010年2月对塔克拉玛干沙漠腹地塔中不同高度沙尘气溶胶质量浓度进行连续观测,结合天气资料进行分析。结果表明:①80m高度PM10质量浓度最高,80m高度PM2.5和PM1.0质量浓度明显低于4m高度PM10,80m高度PM1.0质量浓度最低。频繁的沙尘天气是影响不同粒径的沙尘气溶胶浓度含量的主要因素。②夜间至日出,PM质量浓度逐渐降低,最低基本上出现在08:00,随后质量浓度逐渐增大,18:00前后浓度达到最高值,然后又逐步降低。其规律与风速的昼夜变化完全一致。③TSP月平均质量浓度高值主要集中在3—9月,其中4月和5月浓度最高,随后逐渐减低。3—9月也是PM月平均质量浓度的高值区域,4m高度PM10月平均质量浓度最高发生在5月,其浓度为846.0μg.m-3。80m高度PM10浓度远高于PM2.5和PM1.0浓度,PM2.5和PM1.0浓度相差较小。风沙天气对大气中的不同粒径粒子的浓度含量影响较大,风沙天气越多,粗颗粒含量越高,反之则细颗粒越多。④沙尘天气过程中不同粒径沙尘气溶胶质量浓度变化具有晴天<浮尘天气<扬沙天气<沙尘暴天气的规律。各种沙尘天气中,PM10/TSP表现为晴好天气高于浮尘天气,浮尘天气远高于扬沙和沙尘暴天气。⑤沙尘天气过程中,沙尘气溶胶浓度随着粒径的减小,浓度逐渐降低。不同高度、不同粒径的沙尘气溶胶质量浓度每隔3～4d形成一个峰值区,与每隔3～4d出现沙尘天气强度增强过程直接相关。

The mass concentration of dust aerosol at different heights were observed continuously from January 2009 to February 2010 in the Tazhong Atmosphere Environment Observation Station in the Taklimakan Desert hinterland by making use of instruments of Grimm 1.108 Grain Size Analyzer,Thermo RP 1 400 a particle monitor,and TSP sampler.Some results are obtained as follows：（1） The mass concentration of PM10 at 80-m height was the highest,but the mass concentration of PM2.5or PM10 at 80-m height was lower obviously than that of PM10 at 4-m height,and the mass concentration of PM1.0 at 80 m height was the lowest.Occurrence of frequent dust weather events has resulted in the above mass concentration pattern.（2） The PMx mass concentration gradually decreased from midnight to sunrise with the lowest value at 08：00,and then the mass concentration gradually increased with the highest concentration around 18：00,and then decreased again.It was exactly the same with the change of wind speed.（3） High monthly average mass concentration of TSP mainly appeared from March to September,and the highest concentration was in April and May.Also,high monthly average mass concentration of PMx mainly appeared from March to September,with the highest PM10 concentration of 846.0 μg·m-3 at 4 m height appeared in May.（4） The aerosol mass concentration of different diameters in the sand weather follows an order of in clear dayin floating dust dayin blowing sand dayin sandstorm day.The value of PM10/TSP in clear day was higher than that in floating dust day,and that in floating dust day was much higher than that in blowing sand day and sandstorm day.（5） During a dust weather process,dust aerosol mass concentration gradually decreased with the decrease of particle size.A peak value of dust aerosol mass concentration occurred every 3~4 days at different heights and particle diameters,which was accordant with the strengthening variation of dust weather.