西安市2012-2013年大气降尘的磁化率及指示意义

Magnetic Susceptibility of Dustfall in Xi'an City from 2012 to 2013 and Its Environmental Significance

为了了解西安市大气降尘对环境的影响状况,对西安市2012—2013年按月收集的大气降尘样品进行磁化率实验,并与环境质量公报、气象资料的相关数据分析比较。结果表明,2012年和2013年大气降尘样品的低频质量磁化率和高频质量磁化率相对较高,表明西安市大气降尘中亚铁磁性矿物的含量较高。大气降尘的磁化率随时间变化特征与空气污染物月平均浓度随时间的变化特征基本一致,表明大气降尘的磁化率随时间的变化特征可以很好地反映空气污染状况。西安市每年从11月到次年3月开始集中供暖,供暖期间,燃煤量增加,释放到大气中的燃煤等磁性颗粒粉尘的量相应增加,另外受西安市特殊的地形影响,不利于大气粉尘的扩散,导致冬季粉尘的富集进而加剧空气污染。

The paper aims to understand the effects of dustfall on the environment in Xi’an.The test onmagnetic susceptibility was carried out with the dustfall samples of Xi’an.These samples were collectedmonthly from January 2012 to December 2013.The magnetic parameters（χlf,χhf） indicated a relatively highconcentration of magnetic minerals in Xi’an City,dominated by ferrimagnetic minerals.Magneticsusceptibility of dustfall was consistent with the Air Pollution Index（API）,suggested that the χlf coulddemonstrate the air pollution of Xi’an City.In summer the air quality was better and in winter the air waspolluted strongly.The concentration of magnetic minerals and air quality had significant changes according tothe seasons of each year,and the values rose from December to January of next year,and decreased in summer,which not only came from the pollution of coal-burning,but were also influenced by the special meteorologicalconditions of temperature inversion in winter.