亚洲沙尘两大源区之一——中国戈壁沙漠的气溶胶表征与识别

Characterization of Dust Aerosols over China Gobi Desert,One of the Two Major Sources of Asian Dust

源于中国戈壁沙漠的亚洲沙尘可以通过长途传输到我国下游城市地区并进入太平洋,对城市空气质量、海洋初级生产力及全球气候产生重要影响.于2006~2008年春季对位于中国戈壁沙漠东北部多伦地区气溶胶的理化特性进行了研究,并与其他亚洲沙尘源区的气溶胶作比较.发现2006~2008年多伦地区TSP的平均浓度分别为446.4,183.7,176.1μg/m3,PM2.5的平均浓度分别为125.6,86.7,77.9μg/m3.气溶胶中Cu、P的质量百分数均显著高于地壳中的质量百分数,可能受到内蒙古富含铜矿和磷矿的影响.以多伦为代表的戈壁沙尘气溶胶[Ca〗/[Al]平均比值为0.5左右,低于源于中国西部（新疆地区）的沙尘（1.5）;沙尘暴期间的[Na＋]/[Na],[Mg2＋]/[Mg],和[SO42-〗/3/[S]也低于其他沙尘源区的比值,表明中国戈壁沙漠相比于其他源区将向下游地区输送较多不可溶的钠、镁、硫,对空气质量和气候变化产生不同影响.

China Gobi desert is one the two major source regions for Asian dust.The long-range transport of Asian dust presents significant impacts on the air quality of the down-stream cities,as well as the oceanic primary productivity and thereby global climate system.PM2.5 and TSP aerosols were sampled in the springs of 2006 to 2008 at Duolun（DL） which is located in the northeast of China Gobi desert.The samples were subjected to physicochemical characterization and compared to the Asian dust from other source regions.The mean concentrations of PM2.5 and TSP in the spring of 2006 to 2008 were 125.6,86.7,77.9μg·m-3,and 446.4,183.7,and 176.1μg·m-3,respectively.The mass percentages of Cu and P in the aerosol were much higher than those in soil,which could be attributed to the abundant copper ore and phosphorite at DL.The observed Ca/Al ratios during the dust storm（DS） at DL were lower than those in dust from the western or central Asia.The ratios of Na＋/Na,Mg2＋/Mg,（SO2-4/3）/S at DL were also found to be lower than the dust from other source regions,indicating that China Gobi desert tends to send more insoluble Na,Mg and S compared to other source regions which may have a distinct impact on the air quality and climate change.