1990与2007年兰州冬季大气气溶胶中水溶性离子浓度比较

研究了兰州市1990和2007年冬季在同一地点采集的大气气溶胶样品，使用离子色谱法对其中8种水溶性无机阴离子和6种阳离子进行了分析. 结果发现，17年来由于工业和能源结构的改变以及机动车数量的急剧增加，气溶胶中主要水溶性离子的构成比例和排序正在发生明显变化. 2007年水溶性离子占TSP质量的比例比1990年上升了16%以上，上升最明显的是SO₄2-(4.43%)，NH₄+(3.11%)，Ca2+(2.50%)，NO₃-(2.27%)和Cl-(2.07%). 其主要离子的排序以及在被测阴、阳离子总和中的比例也发生了明显变化. 阴离子中仍然以SO₄2-为首；而阳离子中，1990年是以Ca2+为首，到2007年则变成以NH₄+为首. NH₄+在被测阴、阳离子总和与阳离子总和中所占比例分别上升了7%和6%. 在研究气溶胶的同时，应重视其水溶性离子对人体的危害和影响. 

Comparative Study of Water-soluble Ions in Atmospheric Aerosols in Lanzhou in Winters of 1990 and 2007

Atmospheric aerosol samples were collected at the same site in Lanzhou in the winters of 1990 and 2007. Eight water-soluble inorganic anions and six cations were analyzed by ion chromatography, and the variations of water-soluble ions were also studied. Due to the alteration of energy industrial structure in Lanzhou and the rapid increase in the amount of vehicles, the main composition ratio of water-soluble ions in atmospheric aerosols and order changed greatly in the past 17 years. The ratios of water-soluble ions to the total mass of TSP in 2007 rose more than 16% compared to those in 1990. SO₄^2-, NH₄⁺, Ca²⁺, NO₃^-, and Cl^- were the marked increase of ions, which accounted for 4.43%, 3.11%, 2.50%, 2.27%, and 2.07% respectively of the increased ratio. The order of main ions and the percentage of main ions to the total of anions and cations also changed obviously. SO₄^2- was the dominant anion, while Ca²⁺was the major cation in 1990, while in 2007, NH₄⁺ had become the main cation. The percentage of NH⁺₄to total ions and the ratio of NH₄⁺ to total cations increased 7% and 6%, respectively. We should not only study the harm of organic matter and metal elements in aerosols, but also pay attention to the effect of water-soluble inorganic ions on humans and their harm.Key words: winters in Lanzhou; atmospheric aerosol; water-soluble ions; ion chromatography analysis; energy structure change; comparative study of pollution