中文摘要：

目的了解中国北方沙尘暴易发地区大气颗粒物中铬（Cr）的各形态分布状况。方法于2015年10月17日—12月3日,沿中国北方沙尘暴路线,对6个省（自治区）9个乡镇进行降尘采样,以电感耦合等离子体原子发射光谱法和电感耦合等离子体质谱法为检测方法,并采用Tessier法提取Cr,对Cr的5种形态及其中可交换态和碳酸盐结合态中Cr的价态进行测定。结果承德双塔山镇大气颗粒物中Cr总量最高,达178.672 4μg/g;青海多巴镇Cr含量次之,达132.997 2μg/g;宁夏杨和镇和内蒙古双河镇等乡镇Cr总量较低,为33.370 4-83.577 2μg/g。Cr的各形态含量分布差异较明显,残渣态最多,均占82.4%以上;有机结合态次之,占2.8%-16.0%;可交换态占0.1%-1.6%,碳酸盐结合态占0.7%以内,铁锰氧化物结合态最低。在可交换态和碳酸盐结合态Cr中,主要以Cr-（6＋）存在。承德双塔山镇可交换态Cr的含量低于青海多巴镇,而其他形态Cr均高于青海多巴镇,差异均有统计学意义（P〈0.05）。结论 9个乡镇的Cr污染程度和形态不同,可能与地理位置、周边环境及污染源不同有关;紧邻工业区、处于交通要道的乡镇其毒性最高的可交换态含量最高,污染最严重。

英文摘要：

Objective To learn the chemical fraction distribution of chromium（Cr） in atmospheric particulate matters from nine areas in northern China prone to sandstorm. Methods Through inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometer, the speciations of Cr were abstracted by Tessier method, and its distribution conditions were studied detailedly. Meanwhile, the valence state of Cr in exchangeable state and carbonate combination state were detected. Results Shuangtashan town of Chengde was the traffic route and adjacent to the big city, so its industrial pollution and automobile exhaust pollution were heavy. In general, Cr content was the highest, reached 178.672 4 μg/g, and the next was Duoba of Qinghai,132.997 2 μg/g, which was near by Qinghai metallurgical and chemical industrial zone. Yanghe town of Ningxia and Shuanghe town of Inner Mongolia et al. were far away from cities and industrial zone, so the contents of Cr were relatively low, between 33.370 4 and 83.577 2 μg/g. Various forms of content of Cr distribution differenced larger, the residue state were most between 82.4% and 93.0%, organic binding state within 2.8%-16.0%, exchangeable state within 0.1%-1.6%, carbonate state was under 0.7%, iron and manganese oxides binding state was the lowest, and some were even not detected. The amount of exchangeable and carbonate Cr was less, and it mainly existed as Cr-（6＋）. Compared with Qinghai Duoba Town, the content of exchangeable state Cr was lower, and other four states were higher in Chengde Shuangta town（P〈0.05）.Conclusion Due to the different geographical location, the surrounding environment and pollution source, the levels of Cr pollution of the nine towns are different. Regions, close to the industrial zone and nearby the transportation hub, the exchange fraction is the highest, which the toxicity is the highest, resulting in the most serious pollution.