北京新粒子生成事件期间颗粒物数浓度变化及颗粒增长特征  

Changes of Particle Number Concentration and Characteristics of Particle Growth During the New Particle Formation Event in Beijing

作　　者：马立亚 姚小红[1,2] MA Li-Ya;YAO Xiao-Hong(Key Laboratory of Marine Environmental Science and Ecology,Ocean University of China,Qingdao 266100,China;Laboratory for Marine Ecology and Environmental Science,Pilot National Laboratory for Marine Science and Technology(Qingdao),Qingdao 266237,China)

机构地区：[1]中国海洋大学海洋环境与生态教育部重点实验室,山东青岛266100 [2]青岛海洋科学与技术试点国家实验室海洋生态与环境科学功能实验室,山东青岛266237

出　　处：《中国海洋大学学报（自然科学版）》2020年第12期22-32,共11页Periodical of Ocean University of China

基　　金：国家重大研究发展计划项目(2016YFCD200504);国家自然科学基金项目(41576118,41430646)资助。

摘　　要：本研究分析了2011年冬季、2012年春季和2014年夏季3次短期观测实验中北京城市大气新粒子生成(NPF)事件的季节特征。结果显示,116天的观测中,共发生37次NPF事件(频率为32%)。尽管不同于NPF事件中新粒子核模态颗粒物数浓度的最大净增长量(NMINP)变化显著,春、夏季观测期间的NMINP平均值非常接近,分别为1.60×104和1.57×104 cm-3,冬季均值大幅下降至0.83×104 cm-3。统计分析发现,NMINP和新粒子生成速率(J8~20 nm)及SO2浓度在特定条件下存在相关性,此时NMINP可以由J8~20 nm和SO2浓度近似计算;但是除特定条件外,新粒子形成受多因素共同影响,导致J8~20 nm和NMINP之间缺乏相关性,NMINP和SO2浓度相关性也显著下降。考虑新粒子对气候的潜在影响,即只有粒径增大到50 nm以上的新粒子可在大气超饱和度大于0.6%的条件下活化为云凝结核,而粒径达到70~80 nm的新粒子可以在常见大气超饱和度下活化为云凝结核,本研究引入了新粒子的最大中值粒径(Dpgmax)这一概念。根据最终Dpgmax将观测到的37例NPF事件分为3类,类型I(最终Dpgmax在10~15 nm)、类型II(最终Dpgmax在27~48 nm)和类型III(最终Dpgmax可达75~120 nm)。类型I,II,III分别占总观测事件的22%,16%,30%,其余32%的事件无法确定最终Dpgmax。值得注意的是,只在夏季观测到了类型III。统计分析显示,低Ox(NO2+O3)浓度不利于新粒子增长到类型II和III。基于类型II和III的分析,发现硫酸蒸汽浓度对此类新粒子增长的贡献小于10%,日间Ox氧化有机物很可能是促使新粒子增长的主要原因,夜间硝酸铵和有机物均可能促使新粒子增长。This study analyzed the seasonal characteristics of new particle formation(NPF)events in the urban atmosphere of Beijing during three short-term observation experiments in winter of 2011,spring of 2012,and summer of 2014.37 NPF events were observed during 116 observation days,with the occurrence frequency of 32%.The net maximum increase in the nucleation mode particle number concentration(NMINP)varied largely from event to event,but the monthly averages in spring and summer were generally closer to each other,i.e.,1.60×104 m-3 vs 1.57×104 cm-3.While it decreased to 0.83×104 cm-3 in the winter.Statistical analysis also found that NMINP was correlated with the formation rate(J8~20 nm)of new particles and concentration of SO2 under certain conditions and NMINP could be approximately calculated by J8~20 nm and the concentration of SO2.Besides the specific conditions,the combined effect of multiple factors on the formation of new particles resulted poor correlation between J8~20 nm and NMINP and poor correlation between NMINP and SO2.Considering the impact on climate,only new particles with diameters larger than 50 nm can be activated into cloud condensation nuclei under high supersaturation,e.g.,>0.6%.When newly formed particles grow with diameters greater than 70~80 nm,these new particles yield an obvious contribution to the CCN population at normal supersaturation.In this study,the concept of maximum median particle size(Dpgmax)of new particles was introduced.According to the final Dpgmax,NPF events were identified into three types.Type I(final Dpgmax at 10~15 nm),II(final Dpgmax at 27~48 nm)and III(final Dpgmax at 75~120 nm)accounted for 22%,16%and 30%of the 37 observed NPF events,respectively.Remaining 32%hadn’t the final Dpgmax.Type III NPF events only occurred in summer.It was difficult for new particles to grow to Type II and III,with the low concentration of Ox(NO2+O3).Based on the research of Type II and III,Sulfuric acid vapors contributed no more than 10%to the growth of new particles.Oxidation of org

关 键 词：新粒子生成 新粒子增长 颗粒物数浓度 硝酸铵 二次有机气溶胶 

分 类 号：X513[环境科学与工程—环境工程]