庐山三级分档雾水化学特征的对比分析

为研究庐山冬季不同粒径雾滴化学成分特征，于2015年和2016年在庐山开展冬季云雾物理化学特征的很高综合观测实验，利用主动式分档雾水采集器（three-stage CASCC）共采集44组3级粒径雾滴的雾水样品，其分档空气动力学直径为4~16μm（S3级），16~22μm（S2级）和>22μm（S1级）.用850professional IC型色谱仪（瑞士万通）分析雾水中的水溶性离子浓度，讨论3级分档雾水化学特征和不同粒径雾水中各离子组分的来源及相关性.结果表明，2015年和2016年庐山冬季3级雾水多呈酸性，2016年酸性更强，pH值与雾滴的粒径大小有依赖性关系，4~16μm的小雾滴酸性更强.雾水中主要离子有Ca²⁺，NH₄⁺，SO₄^2-，NO₃^-和Cl^-.NH₄⁺，SO₄^2-，NO₃^-主要集中在4~16μm的小雾滴中，受海洋和土壤源的影响比较小，主要是人为活动所导致，2015年雾水Cl^-主要受人为源的影响，2016年人为输入显著降低，主要受海洋源影响.Mg²⁺，Ca²⁺主要集中在>22μm的大雾滴中.SO₂、NO_x排放逐年降低导致2016年雾水中SO₄^2-和NO₃^-浓度明显小于2015年.

Comparative analysis of the chemical properties of the three-stage fog water in Mount Lushan

In order to investigate the physical and chemical properties of fog water in Mount Lushan, comprehensive observations were carried out during the wintertime of 2015 and 2016. A three-stage Caltech Active Strand Cloud Collector (CASCC) was used to collect the fog droplets within three size ranges (4~16μm, 16~22μm and >22μm), and in total 44 samples were obtained during the observations. Concentrations of cations and anions in each sample were also measured by using Ion Chromatography instrument. We then analyzed the correlation between the ions in each stage as well as the sources of these ions. The composition and the chemical characteristics of the fog water were also given. The results showed that the fog water in 2015 and 2016 was mostly acidic, while the pH value is lower in 2016. A correlation between the pH value and the droplet size was also found, showing a stronger acidity for smaller droplets. The major ions found in fog water were Ca²⁺, NH₄⁺, SO₄^2-, NO₃^- and Cl^-. NH₄⁺, SO₄^2-, NO₃^- mostly reside in small droplets, and they are strongly influenced by the human activities instead of the natural sources such as ocean and soil. It is interesting to find that Cl^- in 2015 was mainly affected by anthropogenic sources while in 2016 they were influenced by marine sources due to a significant reduction of the human inputs. Moreover, Mg²⁺ and Ca²⁺ were found mostly concentrated in large droplets. Due to the decrease of SO₂ and NO_x emission, the concentrations of SO₄^2- and NO₃^- in fog water in 2016 were found remarkably lower than those in 2015.