Department of Chemistry, State Key Laboratory of Marine Pollution, City University of Hong Kong, Hong Kong, China; Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519080, China.
Guangdong Key Laboratory of Environmental Pollution and Health, School of Environment, Jinan University, Guangzhou 511443, China.
Sci Total Environ. 2021 May 1;767:144267. doi: 10.1016/j.scitotenv.2020.144267. Epub 2021 Jan 2.
Few studies have focus on size-segregated particulate polycyclic aromatic hydrocarbons (PAHs) in the oceanic atmosphere. To better understand the impacts of anthropogenic activities on atmospheric PAHs, a heavily human-impacted estuary, the Pearl River Estuary (PRE), was chosen as a case study. We collected gaseous and size-segregated particulate samples of ambient air at two sites in the PRE, as well as from the exhaust emissions of the cruise ship used in the sampling campaign. In addition, surface seawater samples were collected. Size distribution patterns of high molecular-weight (HMW) particulate PAHs were bimodal at one site and unimodal at the other, suggesting PAHs at the former site were derived not only from long-range atmospheric transport but also from local sources. Gas-particle partition coefficients of HMW PAHs in size-segregated particles varied with particle sizes, mostly higher in fine particles (<1.8 μm). Dry deposition flux of ΣPAHs (defined as the sum of 23 PAHs) was contributed mainly from coarse particles (>1.8 μm), and HMW PAHs with lower dry deposition velocities could be transported farther away. With respect to air-water exchange, lower MW PAHs tended to have net volatilization, whereas higher MW PAHs were likely to have net deposition. This study sheds new lights on the origins and fate of atmospheric PAHs over the PRE, and suggests the emissions of maritime traffics should be regulated. Collected near the metropolitan regions, atmospheric PAHs over the PRE were highly affected by anthropogenic activities, especially for HMW PAHs, which could pose a long-lasting impact to the oceanic atmosphere and marine organisms.
鲜有研究聚焦于海洋大气中不同粒径颗粒态多环芳烃（PAHs）。为了更好地了解人为活动对大气 PAHs 的影响，本研究选择人为活动影响严重的珠江口作为案例研究区域。我们在珠江口的两个站点以及采样过程中使用的游轮的尾气排放中采集了环境空气的气态和粒径分级颗粒物样品，此外，还采集了表层海水样品。一个站点的高分子量（HMW）颗粒态 PAHs 的粒径分布模式呈双峰型，而另一个站点呈单峰型，表明前者的 PAHs 不仅来源于远距离大气传输，还来源于本地源。不同粒径分级颗粒物中 HMW PAHs 的气-粒分配系数随粒径变化而变化，在细颗粒物（<1.8 μm）中通常更高。ΣPAHs（定义为 23 种 PAHs 的总和）的干沉降通量主要来自粗颗粒物（>1.8 μm），而具有较低干沉降速度的 HMW PAHs 可能会被输送到更远的地方。就气-水交换而言，低分子量 PAHs 往往具有净挥发作用，而高分子量 PAHs 则可能具有净沉积作用。本研究为珠江口大气 PAHs 的来源和归宿提供了新的认识，并表明应规范海上交通的排放。珠江口的大气 PAHs 主要受人为活动的影响，尤其是高分子量 PAHs，这可能会对海洋大气和海洋生物造成持久的影响。
