College of Environmental Science, Liaoning University, Shenyang, 110036, China.
Environ Sci Pollut Res Int. 2024 May;31(22):32901-32913. doi: 10.1007/s11356-024-33473-w. Epub 2024 Apr 26.
To investigate the influence of COVID-19 lockdown measures on PM and its chemical components in Shenyang, PM samples were continuously collected from January 1 to May 31, 2020. The samples were then analyzed for water-soluble inorganic ions, metal elements, organic carbon, and elemental carbon. The findings indicated a significant decrease in PM and its various chemical components during the lockdown period, compared to pre-lockdown levels (p < 0.05), suggesting a substantial improvement in air quality. Water-soluble inorganic ions (WSIIs) were identified as the primary contributors to PM, accounting for 47% before the lockdown, 46% during the lockdown, and 37% after the lockdown. Ionic balance analysis revealed that PM exhibited neutral, weakly alkaline, and alkaline characteristics before, during, and after the lockdown, respectively. NH was identified as the main balancing cation and was predominantly present in the form of NHNO in the absence of complete neutralization of SO and NO. Moreover, the higher sulfur oxidation ratio (SOR) and nitrogen oxidation ratio (NOR), along with the significant increase in PM/EC, suggested intense secondary transformation during the lockdown period. The elevated OC/EC ratio during the lockdown period implied higher secondary organic carbon (SOC), and the notable increase in SOC/EC ratio indicated a significant secondary transformation of total carbon. The enrichment factor (EF) results revealed that during the lockdown, 9 metal elements (As, Sn, Pb, Zn, Cu, Sb, Ag, Cd, and Se) were substantially impacted by anthropogenic emissions. Source analysis of PMF was employed to identify the sources of PM in Shenyang during the study period, and the analysis identified six factors: secondary sulfate and vehicle emissions, catering fume sources, secondary nitrate and coal combustion emissions, dust sources, biomass combustion, and industrial emissions, with secondary sulfate and vehicle emissions and catering fume sources contributing the most to PM.
为了研究 COVID-19 封锁措施对沈阳 PM 及其化学成分的影响，我们从 2020 年 1 月 1 日至 5 月 31 日连续采集 PM 样本。然后对样本进行水溶性无机离子、金属元素、有机碳和元素碳分析。研究结果表明，与封锁前相比，封锁期间 PM 及其各种化学成分显著下降（p<0.05），表明空气质量有了显著改善。水溶性无机离子（WSIIs）是 PM 的主要贡献者，封锁前占 47%，封锁期间占 46%，封锁后占 37%。离子平衡分析表明，PM 在封锁前、封锁中和封锁后分别呈中性、弱碱性和碱性特征。NH 被确定为主要平衡阳离子，在 SO 和 NO 没有完全中和的情况下，主要以 NHNO 的形式存在。此外，较高的硫氧化比（SOR）和氮氧化比（NOR）以及 PM/EC 的显著增加表明，在封锁期间发生了强烈的二次转化。封锁期间 OC/EC 比值升高意味着更高的二次有机碳（SOC），SOC/EC 比值的显著增加表明总碳的二次转化显著。富集因子（EF）结果表明，在封锁期间，9 种金属元素（As、Sn、Pb、Zn、Cu、Sb、Ag、Cd 和 Se）受到人为排放的显著影响。利用 PMF 对沈阳研究期间的 PM 来源进行了分析，确定了 6 个因子：二次硫酸盐和机动车排放、餐饮油烟源、二次硝酸盐和煤燃烧排放、扬尘源、生物质燃烧源和工业排放，其中二次硫酸盐和机动车排放以及餐饮油烟源对 PM 的贡献最大。
