天津市有机气溶胶的人为和生物源贡献、大气过程及季节性变化研究

有机气溶胶（OA）主要来源是直接的一次排放源和由颗粒相前体物在大气中发生光化学转换形成，其占细粒子颗粒物质量的90%，对气候有重要的影响，也危害人类的身体健康。亚洲东部大气中高负荷的气溶胶导致中国东部爆发雾霾，尤其是我国京津冀地区。最近研究表明，生物来源对印度东北部和中国的OA也有很大的贡献。然而，这些来源对OA的影响及其季节变化，对于我们了解空气质量和气候变化也是非常关键的，但在中国研究较缺乏。在这次研究中，我们将通过观察天津市长期（一年以上）稳定碳（13C）同位素以及放射性碳（14C）同位素比值，以及该地区背景区（山地和陆上）的短期（每个季节1〜2周）分子标记物，来研究OA的一次源/二次源，自然/人为和化石/生物来源及其季节变化的机制。本研究可以提供OA特征及其每个季节的来源的综合信息，有助于构建大气模型，以更好地估计大气中OA转换机制及其对区域地区的气候影响。

Organic aerosols (OA) are directly emitted from primary sources and produced by chemical reactions of their gaseous precursors in the atmosphere. They often account up to 90% of fine aerosol mass and have a great impact on the Earth’s climate system, cause severe human health risks and play an important role in atmospheric chemistry. High aerosol loadings are observed in the East Asian atmosphere that often lead to haze events in East China, particularly over the Jing-Jin-Ji region. In last two decades, much attention has been paid on atmospheric aerosol research in this region, focusing mainly on sulfate and black carbon, and recognized that fossil fuel combustion is the major source of aerosols followed by Asian dust and biomass burning. On the contrary, recent studies showed that the contributions of OA from biological sources are also significant in Northeast Asia, including China. However, the relative importance of such sources to OA loading and their seasonal variations, which are necessary to understand the air quality and climate changes, are not clear in China. Hence, the studies on sources and atmospheric processing of OA are urgently needed over China, particularly Northeast China where the aerosol loading and haze events are higher. Tianjin is a typical metropolis located adjacent to the Bohai Sea covered with rapidly developing economic zone and also dense forest areas. Further the East Asian monsoon, which forms as a result of the thermal difference between the Asian continent and the Pacific Ocean, controls the source regions of the air masses that arrive in Tianjin. Therefore, Tianjin is an ideal location to study the origins and atmospheric processing of aerosols in Northeast China. Here, we propose to investigate the sources such as primary/secondary, natural/anthropogenic and fossil/biogenic origins of OA and their seasonal variations in Northeast China through long-term (over one year period) observations of molecular marker species, stable carbon (13C) and radiocarbon (14C) isotope ratios in the Tianjin urban atmosphere together with the short-period (~2 weeks in each season) observations at background (mountain and onshore) sites in this region. This research could provide comprehensive measurements of OA and their sources, which would be highly helpful to reconcile the atmospheric models to better estimate the OA budget and impacts in North China and its downwind regions.