南海大气颗粒物数浓度(N_(CN))与云凝结核数浓度(N_(CCN))分布特征及不同来源颗粒物活化特性分析  

Variations in N_(CN)and N_(CCN)and the Activation Properties of Aerosol Particles from Different Sources in the Atmosphere over the South China Sea

作　　者：宫君琳 姚小红 Gong Junlin;Yao Xiaohong(The Key Laboratory of Marine Environmental Science and Ecology,Ministry of Education,Ocean University of China,Qingdao 266100,China;The 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）》2023年第8期16-25,共10页Periodical of Ocean University of China

基　　金：国家自然科学基金项目(41776086)资助。

摘　　要：本研究于2020年9月,在中国南海进行大气颗粒物粒径分布(PNSDs)与云凝结核数浓度(N_(CCN))观测,并在剔除船舶自身排放的污染信号数据后进行了颗粒物数浓度(N_(CN))、吸湿性参数(κ)与活化率(AR)计算分析。研究结果显示,南海海域N_(CN)范围为(0.78~34)×10^(3)cm^(-3),计算均值为(4.1±4.0)×10^(3)cm^(-3),与未受到明显陆源颗粒物传输影响时段下的清洁海洋背景数浓度值相比高约一个数量级。结合后向气流轨迹分析发现,南海秋季颗粒物受陆源与海洋源的共同影响,当受陆源影响为主时,气溶胶颗粒物主要来自亚欧大陆与菲律宾群岛,对应来源下的N_(CN)均值分别为(2.7±0.68)×10^(3)cm^(-3)与(8.3±4.9)×10^(3)cm^(-3),在过饱和度(SS)为0.4%下,N_(CCN)(N_(CCN0.4))均值分别为(1.5±1.3)×10^(3)cm^(-3)与(0.88±0.61)×10^(3)cm^(-3),由于菲律宾群岛的颗粒物老化程度低,导致对应SS=0.4%过饱和度下活化率(AR_(0.4))为15%,明显低于亚欧大陆气团(20%)。海洋源颗粒物数浓度为(2.2±0.65)×10^(3)cm^(-3),N_(CCN0.4)为(0.48±0.20)×10^(3)cm^(-3),且N_(CN)和N_(CCN)随风速的增加均略有升高,但AR值基本不变。亚欧大陆源与海洋源颗粒物粒径分布呈现明显的Aitken模态与积聚模态双峰分布特征,但来自菲律宾群岛的颗粒物整体呈现较高浓度水平,并主要集中分布在Aitken模态,积聚模态颗粒物不明显。在9月17与18日观测到两次由气溶胶核模态开始持续数小时的新粒子生成事件(NPF),N_(CN)相比观测期间均值增加了近一倍。由于17与18日颗粒物模态分布存在差异,17日可活化颗粒物数浓度以及积聚模态颗粒物数浓度较多,导致17日活化形成的N_(CCN)与κ值和18日相比存在差异性。本研究通过对中国南海大气颗粒物与云凝结核(CCN)观测数据的分析,为研究不同海洋环境特征下颗粒物对活化形成CCN的差异提供了科学依据。In the study,the observed particle number size distributions(PNSDs)and the number concentration of cloud condensation nuclei(N_(CCN))were analyzed in September of 2020 over the South China Sea.The cumulative number concentration of aerosol particle(N_(CN)),hygroscopicity parameter(κ)and activated ratio(AR)were calculated and analyzed after removing the signal of ship itself pollution.It was shown that the range of N_(CN)was(0.78~34)×10^(3)cm^(-3),and the observed N_(CN)was(4.1±4.0)×10^(3)cm^(-3)in average,which was about one order of magnitude higher than those of the clean oceanic atmosphere when there was without obvious influence from the continental outflow.In the analysis of HYSPLIT 72 h back-trajectories,the particles in the atmosphere over the South China Sea were in the mixed influence from the continental aerosols and the oceanic aerosols.When particles were influenced by those from the continent,the sources of the aerosols were mainly from the Asia and the Philippines,where the averaged N_(CN)were at(2.7±0.68)×10^(3)cm^(-3)and(8.3±4.9)×10^(3)cm^(-3),respectively.The averaged N_(CCN)at SS=0.4%(N_(CCN0.4))was(1.5±1.3)×10^(3)cm^(-3)from the Asian outflow,and(0.88±0.61)×10^(3)cm^(-3)from the Philippine pollution.Since the particles from the Philippine outflow were not aged enough to be easily activated as CCN,the value of AR was only 15%which was less than the bulk of aerosols from the Asian outflow(20%).When the particles were from the ocean,the averaged N_(CN)was(2.2±0.65)×10^(3)cm^(-3),the averaged N_(CCN0.4) was(0.48±0.20)×10^(3)cm^(-3).The values of N_(CN)and N_(CCN)were increased a little with the wind speed increasing,but the value of AR changed little under different wind speed.The PNSDs which from the Asian outflow and the sea spay aerosols were showed obviously with bimodal distribution characteristics which was in Aitken mode and accumulation mode.However,the particles from the Philippines showed a high concentration level with the mainly PNSDs in the Aitken mode,and particles in

关 键 词：大气颗粒物 云凝结核 粒径分布 颗粒物来源 新粒子生成 

分 类 号：X142[环境科学与工程—环境科学]