汾河平原城市秋冬季PM_(2.5)中碳质组分特征及来源解析

Characteristics and source apportionment of carbon components in PM_(2.5) in autumn and winter in cities of Fenhe Plain

碳质组分是PM_(2.5)中的重要组成部分,对气溶胶辐射强迫、全球温室效应、能见度和人体健康等方面都有重要影响,因此对其特征及来源进行分析具有重要意义.本研究以汾河平原城市为研究对象,采集2020年11月—2021年1月PM_(2.5)样品,采用热/光分析仪分析PM_(2.5)中的碳质组分,并通过PMF模型对该地区碳质组分的来源进行解析.结果表明,采样期间PM_(2.5)浓度较高的为晋中(82.1μg·m^(-3)),运城(79.6μg·m^(-3))和临汾(74.4μg·m^(-3));有机碳(OC)浓度较高的为运城(11.2μg·m^(-3))和临汾(11.0μg·m^(-3)),元素碳(EC)浓度较高的为晋中(6.0μg·m^(-3))和运城(4.7μg·m^(-3)).各城市二次有机碳(SOC)浓度较高的为运城(3.0μg·m^(-3)),三门峡(2.5μg·m^(-3))和临汾(2.5μg·m^(-3)),但三门峡(40.3%)和吕梁(32.4%)的SOC占OC比例较高.相关性分析表明,采样期间汾河平原城市的OC、EC和SOC与污染物SO_(2)、NO_(2)和CO浓度呈显著正相关,说明采样期间汾河平原城市受到燃煤、工业以及机动车排放的影响.源解析结果显示,汾河平原城市碳质组分主要污染源的贡献最大为燃煤源(25.5%),其次是柴油车排放源(22.5%)、汽油车排放源(22.3%)和扬尘源(18.3%),生物质燃烧源(11.4%)贡献最小.燃煤源是汾河平原城市碳质组分的主要贡献源,是该地区的重点管控源;此外机动车对汾河平原城市碳质组分的影响不容小觑,尤其是柴油车.本研究从浓度特征、城市变化及来源解析等方面揭示了汾河平原各城市碳组分的污染特征和污染来源情况,为在区域层面对PM_(2.5)的控制提供了数据支撑和管控思路.

Carbon is an important component of PM_(2.5),which has important effects on aerosol radiative forcing,global warming,atmospheric visibility and human health,etc.It is of great significance to analyze its characteristics and sources.In this study,PM_(2.5) samples were collected from November 2020 to January 2021 in Fenhe Plain cities,and the carbonaceous components in PM_(2.5) was analyzed using a heat/light analyzer.Meanwhile,sources apportionment of carbonaceous components in study area was performed via PMF.The results showed that the concentrations of PM_(2.5) were higher in Jinzhong(82.1μg·m^(-3)),Yuncheng(79.6μg·m^(-3))and Linfen(74.4μg·m^(-3)).The organic carbon(OC)concentration was higher in Yuncheng(11.2μg·m^(-3))and Linfen(11.0μg·m^(-3)),and the concentration of elemental carbon(EC)was higher in Jinzhong(6.0μg·m^(-3))and Yuncheng(4.7μg·m^(-3)).The highest concentration of secondary organic carbon(SOC)was found in Yuncheng(3.0μg·m^(-3)),Sanmenxia(2.5μg·m^(-3))and Linfen(2.5μg·m^(-3)),but Sanmenxia(40.3%)and Lvliang(32.4%)had a higher proportion of SOC to OC.Correlation analysis showed the OC,EC and SOC concentration of the cities in the Fenhe plain were significantly positively correlated with the pollutants of SO_(2),NO_(2) and CO during the sampling period,indicating that Fenhe plain cities were greatly affected by the emissions of coal,industry and vehicles.Results of source apportionment showed that coal combustion source(25.5%)contributed the most to carbon components in Fenhe Plain,followed by diesel vehicle exhaust(22.5%),gasoline vehicle exhaust(22.3%),dust source(18.3%),and biomass combustion source(11.4%)contributed the least.Coal combustion source is the main contributor to the carbonaceous components in Fenhe Plain cities and are the key sources to be controlled in this area.In addition,the impact of motor vehicles on the carbonaceous components should be paid attention to,especially diesel vehicles.This study reveals the pollution characteristics and sources of carbonaceous components in the cities of the Fenhe Plain in terms of concentration characteristics,concentration difference in cities and sources apportionment,which provides data support and management thoughts for local management on PM_(2.5) control.