嘉善冬季PM2.5化学组分特征及来源分析

为研究嘉兴地区嘉善冬季污染时段和清洁时段PM_2.5化学组分特征,结合气象数据对2019年1月嘉兴市嘉善县善西超级站在线自动监测PM_2.5及化学组分数据、气态污染物(NO₂和SO₂)进行了分析.结果表明,2019年1月嘉善善西超级站污染时段PM_2.5浓度(97.18μg·m^-3)为清洁时段(36.77μg·m^-3)的2.6倍.污染时段水溶性离子浓度(41.58μg·m^-3)较清洁时段(19.82μg·m^-3)高21.76μg·m^-3,但占比有所降低,含碳组分比例增加.OC;EC比值为3.93,可能受到燃煤及机动车排放的共同影响.低风速及高湿有利于NO₂和SO₂等气态污染物进行二次转化,污染时段硫转化率和氮转化率均比清洁时段高,分别增高7.93%和54.11%,说明NOx向硝酸盐二次转化较为明显,导致颗粒物浓度升高.聚类分析结果显示67.34%气流来自北方,且相应的气流轨迹上污染物浓度比周边高,说明污染物存在一定的长距离输送.结合风玫瑰图可以看出,污染主要为本地及其周边的输送,污染物的长距离输送在短时会使污染浓度突增.因此,在重点关注本地及周边污染的同时,偏北气流下的污染物区域输送不可忽视.

Chemical components characteristic and source apportionment of PM2.5 during winter in Jiaxing

In order to study the characteristics of PM_2.5 components between pollution period and cleaning period juring winter in Jiaxing area,combined with meteorological data,the PM_2.5 and component data,gaseous pollutants(SO₂ and NO₂)of Jiaxing Shanxi super station in January 2019 were analyzed.The results showed that in January 2019,the PM_2.5 concentration(97.18μg·m^-3)of Shanxi super station in Jiaxing was 2.6 times of that in clean period(36.77μg·m^-3).The concentration of water-soluble ion in pollution period(41.58μg·m^-3)was higher than that in clean period(19.82μg·m^-3)about 21.76μg·m^-3,but the proportion decreased and the proportion of carbon component increased.The OC;EC ratio was 3.93,which might be affected by both coal and vehicle emissions.During the pollution period,low wind speed and high humidity were conducive to the secondary transformation of gaseous pollutants such as NO₂ and SO₂,resulting in the increase of particle concentration.In the pollution period,SOR and NOR were higher than those in the clean period,increased by 7.93%and 54.11%respectively,and the secondary transformation of NOx to nitrate was more obvious.Cluster analysis showed that 67.34%of the air flow came from the north,and the concentration of pollutants in the corresponding air flow path was higher than that in the surrounding areas,which indicating that there was a certain long-distance transportation of pollutants,Combined with the wind rose diagram,it could be seen that the pollution was mainly the local and its surrounding transportation,and the long-distance transportation of pollutants would increase the pollution concentration suddenly in a short time.Therefore,while focusing on the local and surrounding pollution,the regional transportation of pollutants under the northerly airflow can not be ignored.