塔里木盆地现代天然降尘磁性特征时空对比研究  

Spatial and Temporal Characteristics in Magnetic Properties of Dustfall in Tarim Basin,Northwestern China

作　　者：王博[1] 许淑婧[1] 夏敦胜[1,2] 贾佳[1] 赵爽[1] 

机构地区：[1]兰州大学西部环境教育部重点实验室,甘肃兰州730000 [2]中国科学院寒区旱区环境与工程研究所沙漠与沙漠化重点实验室,甘肃兰州730000

出　　处：《中国沙漠》2013年第3期840-849,共10页Journal of Desert Research

基　　金：国家自然科学基金项目(41071125;40871090);国家重点基础研究发展计划项目(2010CB950204)资助

摘　　要：塔里木盆地是北半球中、高纬度粉尘的重要源区。本研究在盆地南部的民丰县设置现代粉尘采样点,于2006年1月至2007年12月逐月采集样品。研究结果表明民丰县自然粉尘的月沉降通量为49.95g.m-2,春、夏、秋季数值接近,冬季最低。粉尘中磁性矿物含量低,晶体粒径粗,矫顽力高,赤铁矿含量低。塔里木盆地自然粉尘和黄土高原黄土的磁学性质对比分析结果显示:黄土高原黄土的初始磁化率略低于塔里木盆地的现代降尘,二者的原生强磁性矿物的晶体粒径较粗,约为5μm。粉尘在黄土高原沉积后,随着成壤过程中的生物化学风化作用加强,大量细粒强磁性矿物生成。同时,赤铁矿含量的增加也是指示成壤作用强度的重要标志。在塔里木盆地,人为源粉尘的磁性特征主要表现在强磁性和较低的矫顽力两方面。对盆地边缘地区的城市粉尘调查结果发现:北部城市粉尘的人为源输入强度高,磁学信号强;南部城市相对较弱。这与当地的经济发展状况、人口密度具有良好对应关系。环境磁学是进行粉尘环境监测和物源示踪的有效手段。Tarim Basin is one of the most important sources of dust on the earth, especially in north hemi- sphere. In this study, samples of dustfall were collected at each month from January of 2006 to December of 2007 in Minfeng county of Tarim Basin, and a set of environmental magnetic parameters （χlf, χfd %, χARM, SIRM, HIRM and Hcr） were measured. Results suggest that the mean monthly dust deposition flux values is 49.95 g. m2, with low in winter and high in spring, summer and autumn. The magnetic assemblage in the dustfall is dominated by coarse grained and high coercivity magnetite being associated with maghaemite and haematite. The contrast between dustfall and Loess Plateau loess reveals that the primary strong magnetic mineral is slightly lower than dustfall in Tarim Basin, and both of which present coarse grain size of magnetic mineral （about 5 μm）. Furthermore, the magnetic investigation also suggests hematite concentration en- hancement in loessic soil is another important signal of pedogenic. Anthropogenically derived particulate matter presents higher ferrimagnetic mineral concentration and low coercivity in Tarim Basin. The contrast of dustfall in different cities of Tarim Basin indicates that magnetic signal is strong in cities （Aksu, Korla） in north and weak in south, which has a good corresponding relationship with economic development and popu- lation density. Environmental magnetism is an effective measurement in monitoring dust pollution and its tracing source.

关 键 词：塔里木盆地 黄土高原 降尘 黄土 环境磁学 

分 类 号：X513[环境科学与工程—环境工程]