绿潮多发期黄海沿岸大气细粒子中有机胺的形成机制研究

Amines as one of the important organic nitrogen, are ubiquitous atmospheric bases, playing a critical role in the atmospheric chemistry. Marine source has been known to be an important source of amine. The ocean surface is like a carbon pool emitting vast of organics including amines, especially during the high biogenic activity when the Green Tide occur. Yet most of previous studies have focused on the bulk measurements with several back draws, which is difficult to analyze the detail physical and chemical process of amines. In comparison, single particle mass spectrometer is the only instrument can supply sufficient high time resolution information on both the size and chemical mixing state of individual particles, which is also critical to understand the characteristics of amines. In the present study, we proposed to conduct simultaneous observation of both single particle and bulk measurements of amine-containing aerosols at three different representative sites in Qingdao during May to August when the Green Tide are frequent. Based on the mixing state of amines, the gas/particle phase amine concentration and other compete gases e.g. NH3 to analysis the spatial and temporal characteristics of aerosol amines, to identify the source apportionment and the major factors controlling the gas/particle partitioning of amines. Surface seawater around the sampling sites is also collected to obtain the indicator of biogenic activity such as the concentrations of Chlorophyll-a, particle and dissolved organics. These information would help us to understand the interaction between the coastal atmosphere and the marine organics during the high biogenic activities periods.

有机胺作为重要的一类有机氮，是大气中极少数碱性物质之一，在大气化学中扮演重要角色。海洋是有机胺的重要来源，尤其是海洋生物活性较高的绿潮多发期，海洋表层就像一个强大的有机池释放包含有机胺在内的各种有机物，但受限于传统分析方法的弊端对颗粒态有机胺生成过程的研究难度很大。单颗粒质谱分析技术是目前唯一可以获取高时间分辨率的有机胺在颗粒相分配状态的方法，也是研究有机胺形成机制的关键环节。本项目拟应用单颗粒质谱仪和全样在线离子分析仪，在绿潮多发期对黄海沿岸不同背景下大气细粒子中的有机胺进行研究，获取有机胺单颗粒物的混合分配状态，结合气态有机胺和NH3等信息，研究不同站点大气细粒子中有机胺的丰度、来源及其气/粒平衡等过程，同时对海水中的叶绿素a、有机碳等海洋生物活性指标进行监测，以期深入认识高海洋生物活性期间，陆源大气与以有机胺为代表的海洋源有机物之间的相互作用及该作用对沿海不同站点大气化学成分的影响。

有机胺作为重要的一类有机氮，是大气中极少数碱性物质之一，在大气化学中扮演重要角 色。海洋是有机胺的重要来源，尤其是海洋生物活性较高的绿潮多发期，海洋表层就像一个强大的有机池释放包含有机胺在内的各种有机物，但受限于传统分析方法的弊端对颗粒态有机胺生成过程的研究难度很大。本项目应用全样分析和单颗粒质谱仪等多种研究方法，对夏秋冬三季黄渤海沿岸不同背景下大气细粒子中的三甲基胺(TMA)，二甲基胺(DMA)和二乙基胺(DEA)等有机胺进行研究。其中夏季临海(LQH)和城郊站点(OUC)的单颗粒对比研究发现，临海站点有来自于海洋源的强烈的TMA信号，其生成受到了温湿度的显著影响，呈现日低夜高的日变化趋势。主要由TMA同大气背景中存在的BC等颗粒物混合，而城郊站点由于复杂的来源和城市背景大气的影响，以DEA为主导，并且有机胺同OCEC和K+等典型陆源示踪物相混合。冬季奥帆中心(OSC)和黄渤海巡航观测(YBS)则发现较强的TMA信号，一方面是受到海洋大风的影响释放出较高的TMA，另一方面在山东半岛沿岸海水中丰富的叶绿素的环境背景下受到生源的影响生成。两种情形下TMA的混合状态有显著区别。基于膜样品采集的方法对黄渤海三个季节四次巡航观测的结果发现临近上海的海域（32-34°N）往往具有较高的有机胺，同卫星数据获取的该区域相对丰富的叶绿素含量相符。同时也发现了夏季TMA同走航期间海水中的叶绿素实测浓的线性相关性较好，再次印证了TMA同海洋生物源相关。对沿岸临海陆地站点(QD)三个季节气溶胶的观测则发现有机胺丰度受到了海陆的相互影响，季节变化显著。当夏季受到海洋源影响较大的环境背景下其TMA的丰度和占比显著提高。在我国污染防控逐渐加强的环境背景下，沿海城市受到海洋源的影响日益显著，本研究的结果有助于进一步认识华北沿岸含有机胺的丰度和空间分布及形成机制，为有机胺对城市气溶胶空气质量的影响研究奠定基础。