2020年南通市大气颗粒物组分和污染特征分析

Analysis of composition and pollution characteristics of atmosphericparticulate matter in Nantong City in 2020

本次研究以南通市大气颗粒物组成和污染特征为研究对象,利用南通市大气超级站监测数据,分析了2020年南通市PM_(2.5)和PM_(10)浓度水平,时间变化特征和组分特征。结果表明,2020年南通市PM_(2.5)和PM_(10)年均质量浓度分别为34μg/m^(3)和56μg/m^(3),具有明显的冬高夏低的特征,PM_(2.5)/PM_(10)呈现为冬季>夏季>春季≈秋季。PM_(2.5)中含碳组分和水溶性阴阳离子高低顺序为:NO_(3)^(-)>OC>SO_(4)^(2+)>NH_(4)^(+)>EC>Cl^(-)>K^(+)>Na^(+)>Ca^(2+)>Mg^(2+)。冬季OC、NH_(4)^(+)、SO_(4)^(2+)和NO_(3)^(-)浓度值显著高于其他三个季节,PM_(2.5)中NO_(3)^(-)、OC、SO_(4)^(2+)和NH_(4)^(+)的占比分别为27.7%、15.4%、15.0%和14.2%。NO_(3)^(-)/SO_(4)^(2+)比值为1.9,表明受移动源影响较大;OC和EC浓度均为冬季最高,夏季最低,四季OC/EC介于3.2~4.6,表明南通全年均受二次有机碳(SOC)的影响,且主要受柴油、汽油车的尾气排放和燃煤排放影响。

Using the monitoring data of Nantong Superstation,the concentration level,time variation characteristics and composition characteristics of PM_(2.5)and PM_(10)in Nantong City in 2020 were analyzed.The results showed that the average annual mass concentrations of PM_(2.5)and PM_(10)in Nantong in 2020 were 34μg/m^(3)and 56μg/m^(3)respectively,with an obvious characteristic of high in winter and low in summer.PM_(2.5)/PM_(10)in order of high to low for seasons as:winter>summer>autumn≈spring.The order of carbon components and water-soluble anions in PM_(2.5)was NO_(3)^(-)>OC>SO_(4)^(2+)>NH_(4)^(+)>EC>Cl^(-)>K^(+)>Na^(+)>Ca^(2+)>Mg^(2+).The concentration values of OC,NH_(4)^(+),SO_(4)^(2+)and NO_(3)^(-)in winter were significantly higher than those in the other three seasons,and the proportions of NO_(3)^(-),OC,SO_(4)^(2+)and NH_(4)^(+)in PM_(2.5)were 27.7%,15.4%,15.0%and 14.2%respectively.The ratio of NO_(3)^(-)/SO_(4)^(2+)is 1.9,which indicates that the mobile source has a large contribution.The concentrations of OC and EC were the highest in winter and the lowest in summer,and the OC/EC in four seasons ranged from 3.2 to 4.6,indicating that secondary organic carbon(SOC)had some pollution throughout the year in Nantong,and was mainly sourced from exhaust emissions of diesel and gasoline vehicles and coal burning emissions.