新冠疫情管控期间西安细颗粒物中碳组分浓度变化特征

于2019年1月27日—3月18日及2020年1月27日—3月18日对西安市细颗粒物(PM_2.5)的碳组分浓度进行了在线观测，对比分析了非疫情与疫情期间各常规污染因子、气象要素、PM_2.5中有机碳(OC)和元素碳(EC)的污染特征。结果表明：非疫情与疫情期间西安市的气象条件总体水平较为相近。疫情期间的二氧化硫(SO₂)、臭氧(O₃)浓度相对升高。重污染天气下，除PM_2.5外，其他污染物浓度均降低，说明疫情管制对重污染天气污染物浓度的削弱作用明显。疫情期间，PM_2.5中的OC组分浓度及占比有显著升高，与疫情期间的各类交通管制导致的机动车尾气排放量显著降低有关。另外，OC与EC的相关性较强，说明污染来源与人类日常生活有关。疫情期间西安市颗粒物中碳组分主要来自各类生物质燃烧，并且存在SOC污染，SOC在OC中的占比达到37.8%。疫情期间重污染天气下，SOC在OC中的占比达到87.5%,说明SOC对重污染天气OC的贡献较大。

Characteristic of Carbon Components Concentration Variation in Fine Particles in Xi'an During COVID-19 Pandemic Control Period

Carbon components in fine particulate matter (PM_2.5) at Xi''an (Shaanxi Environmental Monitoring Center Station) was continuously measured from January 27 to March 18,2019 and from January 27 to March 18,2020.And pollution characteristics of conventional pollution factors,meteorological factors,organic carbon (OC) and elemental carbon (EC) in PM_2.5 during non-epidemic and epidemic periods were compared and analyzed.The results showed that the overall level of meteorological conditions in Xi''an during non-epidemic and epidemic was similar.During the epidemic,concentrations of sulfur dioxide (SO₂) and ozone (O₃) were increased.And under the heavy pollution weather,concentration of other pollutants were all reduced except PM_2.5.It illustrated that the epidemic control had a significant weakening effect on concentration of pollutants in heavily polluted weather.During the epidemic,concentration and proportion of organic carbon components in PM_2.5 increased significantly,due to the exhaust emissions of motor vehicles caused by various traffic controls.In addition,correlation between OC and EC was relatively strong.It illustrated that sources of pollution came from human daily activities.Carbon components in the particulate matter in Xi''an during epidemic mainly came from various kinds of biomass burning,and there were SOC pollution.SOC accounted for 37.8% of OC.In heavily polluted weather,SOC accounted for 87.5% of OC during the epidemic,indicating that SOC had a greater contribution to OC in heavily polluted weather.