单颗粒气溶胶质谱仪(SPAMS,single particle aerosol mass spectrometer)可以实时、连续和高时间分辨率的提供单个气溶胶颗粒的粒径和化学组分信息,具有良好的定性能力。但,SPAMS对气溶胶化学组分的定量分析能力尚待评估。采用SPAMS结...
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单颗粒气溶胶质谱仪(SPAMS,single particle aerosol mass spectrometer)可以实时、连续和高时间分辨率的提供单个气溶胶颗粒的粒径和化学组分信息,具有良好的定性能力。但,SPAMS对气溶胶化学组分的定量分析能力尚待评估。采用SPAMS结合滤膜采样的分析方法,于2017-12-01至2018-02-28日在郑州市高新区、航空港区和中原区展开观测,通过对比单颗粒中的元素碳(EC)、有机碳(OC)、硫酸盐、硝酸盐和铵盐的峰面积、数浓度与滤膜采集的质量浓度,以回归分析系数(R)评估了SPAMS对5种组分的定量能力。结果表明:EC单颗粒的数浓度和峰面积与其质量浓度的相关性始终很低(R<0.3),说明尚无法通过相关性分析建立EC单颗粒与质量浓度的定量关系;OC单颗粒与质量浓度的相关性从低度到中度相关分布(0.30.5),可以通过相关性建立硫酸盐、硝酸盐和铵盐的半定量系数。三个站点各组分相关性对比结果表明:中原区各组分数浓度与质量浓度的相关性高于高新区和航空港区,且中原区测径颗粒数浓度与PM_(2.5)质量浓度的相关性也显著高于其他两个采样点,因此测径颗粒数浓度与PM_(2.5)质量浓度的相关性可能是评估SPAMS定量化结果好坏的前提条件。
本研究利用单颗粒气溶胶质谱仪(SPAMS)于2021年1月1日至31日在广州市对大气中含铁颗粒的化学组成、混合状态、来源及其在污染过程中的演变特征进行了研究。结果表明,含铁颗粒主要分为Fe-BB、Fe-C、Fe-D、Fe-HM、Fe-N、Fe-S、Fe-SN等七种类型,以Fe-N、Fe-SN和Fe-HM三类颗粒为主,这三类颗粒在所有含铁颗粒中数量占比达85%。大部分含铁颗粒与二次无机离子尤其是硝酸盐混合,部分含铁颗粒与生物质燃烧源特征离子有机氮、元素碳、沙尘特征组分或重金属混合。在1月13~16日PM2.5重污染过程期间,发生了三次PM2.5突升,分别为污染前期、中期和后期。在污染前期和中期,PM2.5浓度升高受到来自工业排放和机动车尾气的一次排放的含铁颗粒的影响,在污染后期,受到含铁颗粒上硝酸盐生成的影响。To investigate the particle types, mixing states, sources and evolution during pollution of Fe-containing particles, a single particle aerosol mass spectrometer was used to perform an campaign in Guangzhou from January 1 to 31, 2021. The results showed that the Fe-containing particles were classified as Fe-BB, Fe-C, Fe-D, Fe-HM, Fe-N, Fe-S and Fe-SN, which Fe-N, Fe-SN and Fe-HM was the main types, accounted for 85% of all Fe-containing particles. Most of the Fe-containing particles were mixed with secondary inorganic ions, especially nitrate, and some were mixed with the characteristic ions of biomass combustion of organic nitrogen, elemental carbon, dust characteristic components or heavy metals. During the heavy PM2.5 pollution event from January 13 to 16, three spikes in PM2.5 concentrations occurred, which were divided into the early, middle and later stages of pollution. In the early and middle stages of pollution, the increase of PM2.5 concentration was influenced by Fe-containing particles from primary emissions of industrial and vehicle. In the later stages of pollution, the formation of nitrate was the main driver.
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