我国沿海新粒子爆发热点地区碘新粒子的来源及其对大气气溶胶的贡献研究

相比陆地源新粒子，国内外海洋源新粒子研究相对滞后。我国近岸海域因富营养化和藻类养殖，预期碘释放和成核比国外严重，然而我国的海洋源新粒子研究集中于有机胺和甲磺酸，未测量过新粒子的碘组分，未认识到碘的巨大作用，未见沿海碘新粒子的文献发表。申请人经过预研究，首次在中国报导了高频率高强度的碘新粒子生成，在全世界首次用高分辨质谱识别了新粒子中几十种无机和有机碘化物。基于此，本项目将在沿海新粒子爆发热点地区进一步研究碘新粒子的来源和贡献机制，测量碘新粒子的成核与生长动力学，重点识别驱动碘新粒子长到云凝结核粒径的关键性碘化物和非碘组分。针对碘新粒子前驱物大气寿命短、排放呈点源/带状源的特性，本项目将创新性地结合藻类排放源测量和区域模式，首次揭示碘新粒子在水平和垂直空间尺度上对沿海地区气溶胶数浓度和质量浓度的量化贡献。本项目对我国沿海颗粒物复合污染成因有重要意义，也将为碘的生物地球化学循环提供关键性数据。

Compared to new particle formation (NPF) from terrestrial emission sources, NPF from marine precursors are less studied by atmospheric scientists around the world. Growing algae population due to serious eutrophication and algae farming in the coastal waters of China makes the emission of iodine precursors an important NPF source in Chinese coastal areas. However, most of marine/coastal NPF studies in China have focused on amines or methanesulfonic acid, whereas coastal NPF from iodine precursors has not been reported in the literature. The role of iodine has been ignored, mainly because iodine species have never been measured in new particles. Recently, for the first time, our pilot study observed intense coastal iodine-induced NPF hot spot in China. A group of inorganic and organic iodine species were identified, for the first time, in new particles using high-resolution mass spectrometry. Here we propose to further study the source and growth mechanisms of iodine-induced new particles at the coastal NPF hot spot. Nucleation and growth kinetics of iodine-induced NPF will be investigated. In particular, the crucial chemical species driving the growth of iodine new particles to CCN sizes will be investigated. Considering the short lifetime and point/line source emission characteristics of iodine precursors, we will perform regional transport modelling of iodine new particles based on WRF-Chem and the emission rate measurement of macro- and micro algae. As a result, the project will for the first time reveal the contribution of iodine-induced NPF to the number and mass concentrations of atmospheric Particulate Matter (PM) on vertical and horizontal directions in a typical coastal area. The project is not only important for PM control strategy of Chinese coastal regions, but also provides crucial new data for studying the biogeochemical cycle of iodine.