Xie M, Barsanti K C, Hannigan M P, Dutton S J, Vedal S
Department of Mechanical Engineering, College of Engineering and Applied Science, University of Colorado, Boulder, CO 80309, USA.
Department of Civil and Environmental Engineering, Portland State University, P.O. Box 751, Portland, OR 97207, USA.
Atmos Chem Phys. 2013;13:7381-7393. doi: 10.5194/acp-13-7381-2013.
Gas-phase concentrations of semi-volatile organic compounds (SVOCs) were calculated from gas/particle (G/P) partitioning theory using their measured particle-phase concentrations. The particle-phase data were obtained from an existing filter measurement campaign (27 January 2003-2 October 2005) as a part of the Denver Aerosol Sources and Health (DASH) study, including 970 observations of 71 SVOCs (Xie et al., 2013). In each compound class of SVOCs, the lighter species (e.g. docosane in alkanes, fluoranthene in PAHs) had higher total concentrations (gas + particle phase) and lower particle-phase fractions. The total SVOC concentrations were analyzed using positive matrix factorization (PMF). Then the results were compared with source apportionment results where only particle-phase SVOC concentrations were used (particle only-based study; Xie et al., 2013). For the particle only-based PMF analysis, the factors primarily associated with primary or secondary sources ( alkane, EC/sterane and inorganic ion factors) exhibit similar contribution time series ( = 0.92-0.98) with their corresponding factors ( alkane, sterane and nitrate+sulfate factors) in the current work. Three other factors (light alkane/PAH, PAH and summer/odd alkane factors) are linked with pollution sources influenced by atmospheric processes (e.g. G/P partitioning, photochemical reaction), and were less correlated ( = 0.69-0.84) with their corresponding factors (light SVOC, PAH and bulk carbon factors) in the current work, suggesting that the source apportionment results derived from particle-only SVOC data could be affected by atmospheric processes. PMF analysis was also performed on three temperature-stratified subsets of the total SVOC data, representing ambient sampling during cold (daily average temperature < 10 °C), warm (≥ 10 °C and ≤ 20 °C) and hot (> 20 °C) periods. Unlike the particle only-based study, in this work the factor characterized by the low molecular weight (MW) compounds (light SVOC factor) exhibited strong correlations ( = 0.82-0.98) between the full data set and each sub-data set solution, indicating that the impacts of G/P partitioning on receptor-based source apportionment could be eliminated by using total SVOC concentrations.
半挥发性有机化合物（SVOCs）的气相浓度是根据气/粒（G/P）分配理论，利用其测得的颗粒相浓度计算得出的。颗粒相数据来自于丹佛气溶胶源与健康（DASH）研究的一项现有滤膜测量活动（2003年1月27日至2005年10月2日），其中包括对71种SVOCs的970次观测（Xie等人，2013年）。在SVOCs的每一类化合物中，较轻的物种（如烷烃中的二十二烷、多环芳烃中的荧蒽）具有较高的总浓度（气相+颗粒相）和较低的颗粒相分数。使用正定矩阵因子分解（PMF）对SVOCs的总浓度进行了分析。然后将结果与仅使用颗粒相SVOC浓度的源解析结果进行比较（仅基于颗粒的研究；Xie等人，2013年）。对于仅基于颗粒的PMF分析，与一次或二次源主要相关的因子（烷烃、EC/甾烷和无机离子因子）与其在本研究中的相应因子（烷烃、甾烷和硝酸盐+硫酸盐因子）表现出相似的贡献时间序列（=0.92 - 0.98）。其他三个因子（轻质烷烃/多环芳烃、多环芳烃和夏季/奇数烷烃因子）与受大气过程影响的污染源相关（如G/P分配、光化学反应），并且与其在本研究中的相应因子（轻质SVOC、多环芳烃和总碳因子）的相关性较低（=0.69 - 0.84），这表明仅基于颗粒的SVOC数据得出的源解析结果可能会受到大气过程的影响。还对总SVOC数据的三个温度分层子集进行了PMF分析，分别代表寒冷（日平均温度<10°C）、温暖（≥10°C且≤20°C）和炎热（>20°C）时期的环境采样。与仅基于颗粒的研究不同，在本研究中，以低分子量（MW）化合物为特征的因子（轻质SVOC因子）在完整数据集和每个子数据集解决方案之间表现出很强的相关性（=0.82 - 0.98），这表明通过使用总SVOC浓度可以消除G/P分配对基于受体的源解析的影响。
