中文关键词PM_2.5霾有机气溶胶水溶性无机离子临安 英文关键词PM_2.5hazeorganic aerosolwater-soluble inorganic ionsLin'an

作者	单位	E-mail
梁林林	中国气象科学研究院, 灾害天气国家重点实验室和大气化学重点开放实验室, 北京 100081	liang_linlin@126.com
孙俊英	中国气象科学研究院, 灾害天气国家重点实验室和大气化学重点开放实验室, 北京 100081	jysun@cma.gov.cn
张养梅	中国气象科学研究院, 灾害天气国家重点实验室和大气化学重点开放实验室, 北京 100081
刘畅	中国气象科学研究院, 灾害天气国家重点实验室和大气化学重点开放实验室, 北京 100081
徐婉筠	中国气象科学研究院, 灾害天气国家重点实验室和大气化学重点开放实验室, 北京 100081
张根	中国气象科学研究院, 灾害天气国家重点实验室和大气化学重点开放实验室, 北京 100081
刘旭艳	国家卫星气象中心, 北京 100081
马千里	临安大气本底污染监测站, 临安 311307

中文摘要 本研究对长江三角洲背景地区临安大气本底站夏季PM_2.5进行连续采集，并对其分别进行OC/EC和水溶性离子测试分析.研究结果发现，临安夏季PM_2.5中OC和EC平均质量浓度分别为（14.3±3.95）μg·m^-3和（3.33±1.47）μg·m^-3.与城市地区相比，本研究临安背景地区夏季气溶胶中OC和EC相关性较弱（R2=0.31，P<0.01）.二次无机离子，即SO₄^2-、NO₃^-、NH₄⁺（SNA），明显高于其它水溶性无机离子，平均浓度分别为（8.70±5.66）、（2.04±1.07）和（3.25±2.29）μg·m^-3.基于对临安夏季PM_2.5连续加密观测、气团后向轨迹以及火点图研究分析，发现静稳天气条件和区域传输都可以影响临安地区PM_2.5的化学组成特征.此外，通过对临安本底站霾天和清洁天PM_2.5化学组成特征比较发现，与清洁天相比，霾污染天气POC和EC占PM_2.5的质量分数没有明显变化，而SOC占PM_2.5的质量分数却呈现了明显的下降趋势.与SOC不同，SO₄^2-和NH₄⁺占PM_2.5的质量分数在霾污染天气均呈现了上升的趋势，说明二次无机离子有另一种明显增强的化学生成路径，即非均相化学反应. 英文摘要 PM_2.5 samples were collected at a background site of the Yangtze River Delta in China, during summertime, of which the carbonaceous components, i.e., OC and EC, and water-soluble inorganic ions, including sulfate, nitrate, and ammonium, were quantified. The average concentrations of OC and EC in PM_2.5 during summer at Lin'an were (14.3±3.95) μg·m^-3 and (3.33±1.47) μg·m^-3, respectively. Compared to an urban site, the correlation between OC and EC during summertime in Lin'an, which was a rural site, was relatively weak (R²=0.31, P<0.01). The concentrations of secondary inorganic aerosols (sulfate as SO₄^2-, nitrate as NO₃^-, and ammonium as NH₄⁺) were much higher than those of other water-soluble inorganic ions, with average values of (8.70±5.66), (2.04±1.07), and (3.25±2.29) μg·m^-3, respectively. Based on long-term intensive observations, combined with the analysis of back trajectory and fire spots observations, it was revealed that regional transport and stable synoptic conditions both play important roles in controlling the variations in aerosol chemical components. During the transition from clean to hazy days, the EC and POC fractions showed no obvious variation; in contrast, the SOC fraction decreased obviously. Unlike for SOAs, relative contributions of sulfate and ammonia to PM_2.5 increased during hazy days, suggesting enhanced chemical production via other pathways for these two secondary inorganic ions, probably through heterogeneous reactions.

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