Magnetic characteristics of dustfall in urban area of north China and its environmental significance

• Published in: Science China. Earth sciences Vol. 50; no. 11; pp. 1724 - 1732
• Main Authors: Xia, DunSheng, Yang, LiPing, Ma, JianYing, Yu, Ye, Wang, Guan, Chen, FaHu
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01.11.2007; Key Laboratory of Desert and Desertification,Institute of Cold and Arid Regions Environmental and Engineering,Chinese Academy of Sciences,Lanzhou 730000,China; CAEP,Key Laboratory of West China's Environmental System (Ministry of Education),Lanzhou Univers%CAEP,Key Laboratory of West China's Environmental System (Ministry of Education),Lanzhou University,Lanzhou 730000,China%Key Laboratory of Desert and Desertification,Institute of Cold and Arid Regions Environmental and Engineering,Chinese Academy of Sciences,Lanzhou 730000,China
• Subjects: Air pollution; Air quality; Anthropogenic factors; Dust; environmental; Local government; Magnetism; magnetism,dustfall,air; Minerals; Outdoor air quality; Particulate matter; Pollution sources; Pollution studies; pollution,Lanzhou; Public health; Summer; Urban areas; China, People's Rep; air pollution; dustfall; Lanzhou; environmental magnetism
• ISSN: 1674-7313; 1006-9313; 1869-1897; 1862-2801
• DOI: 10.1007/s11430-007-0094-9

Urban particulate pollutants not only affect urban air quality but also directly threaten public health.Lanzhou has been one of the most seriously polluted cities in the world due to its special geophysical location and weather conditions,which makes it an ideal place for urban particulate pollution study.In this study a set of environmental magnetic parameters (χlf,χfd%,χARM,SIRM,HIRM,SOFT and back field IRM) were measured and analyzed for the dustfall samples collected monthly during 1997.4―2000.5 and 2004.11―2005.10 at Lanzhou University campus (KLD and CCS) and at a clear site of Gaolanxian (GLX).Results demonstrate that the main magnetic minerals in the dustfall are magnetite,with some maghaemite and haematite.Cross plots of Mrs/Ms vs.Bcr/Bc and χfd% vs.χARM/SIRM indicate that the main magnetic grain sizes are pseudo-single-domain (PSD).The high concentration of magnetic minerals in the dustfall indicates that Lanzhou is seriously polluted.The main pollution sources are anthropogenic activities and nature dust,with the former posing a great threat during the whole year,which is different from the general view that the natural dust is the main contributor in summer.With great efforts of the government and local authority in the past decades,the air quality in Lanzhou has been improved in winter,but it is not so obvious in summer.This study also reveals that as a simple,rapid and accurate technology,environmental magnetism could be a valuable tool for urban pollution study.