Wu Zilan, Lin Tian, Li Zhongxia, Jiang Yuqing, Li Yuanyuan, Yao Xiaohong, Gao Huiwang, Guo Zhigang
Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Institute of Atmospheric Sciences, Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China.
State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China.
Environ Pollut. 2017 Nov;230:444-452. doi: 10.1016/j.envpol.2017.06.079. Epub 2017 Jul 1.
We measured 15 parent polycyclic aromatic hydrocarbons (PAHs) in atmosphere and water during a research cruise from the East China Sea (ECS) to the northwestern Pacific Ocean (NWP) in the spring of 2015 to investigate the occurrence, air-sea gas exchange, and gas-particle partitioning of PAHs with a particular focus on the influence of East Asian continental outflow. The gaseous PAH composition and identification of sources were consistent with PAHs from the upwind area, indicating that the gaseous PAHs (three-to five-ring PAHs) were influenced by upwind land pollution. In addition, air-sea exchange fluxes of gaseous PAHs were estimated to be -54.2-107.4 ng m d, and was indicative of variations of land-based PAH inputs. The logarithmic gas-particle partition coefficient (logK) of PAHs regressed linearly against the logarithmic subcooled liquid vapor pressure (logP), with a slope of -0.25. This was significantly larger than the theoretical value (-1), implying disequilibrium between the gaseous and particulate PAHs over the NWP. The non-equilibrium of PAH gas-particle partitioning was shielded from the volatilization of three-ring gaseous PAHs from seawater and lower soot concentrations in particular when the oceanic air masses prevailed. Modeling PAH absorption into organic matter and adsorption onto soot carbon revealed that the status of PAH gas-particle partitioning deviated more from the modeling K for oceanic air masses than those for continental air masses, which coincided with higher volatilization of three-ring PAHs and confirmed the influence of air-sea exchange. Meanwhile, significant linear regressions between logK and logK (logK) for PAHs were observed for continental air masses, suggesting the dominant effect of East Asian continental outflow on atmospheric PAHs over the NWP during the sampling campaign.
2015年春季，我们在一次从东海（ECS）到西北太平洋（NWP）的研究航次中，对大气和水体中的15种母体多环芳烃（PAHs）进行了测量，以调查PAHs的存在、海气气体交换和气粒分配情况，特别关注东亚大陆外流的影响。气态PAH的组成和来源识别与上风区域的PAHs一致，表明气态PAHs（三环至五环PAHs）受到上风陆地污染的影响。此外，气态PAHs的海气交换通量估计为-54.2-107.4 ng m² d，这表明陆源PAH输入存在变化。PAHs的对数气粒分配系数（logK）与对数过冷液体蒸气压（logP）呈线性回归，斜率为-0.25。这显著大于理论值（-1），意味着西北太平洋上空气态和颗粒态PAHs之间存在不平衡。PAH气粒分配的不平衡受到海水中三环气态PAHs挥发和较低烟尘浓度的影响，特别是在海洋气团占主导地位时。对PAHs吸收到有机物中以及吸附到烟尘碳上的建模表明，与大陆气团相比，海洋气团的PAH气粒分配状态与建模K的偏差更大，这与三环PAHs的较高挥发相吻合，并证实了海气交换的影响。同时，在大陆气团中观察到PAHs的logK与logK（logK）之间存在显著的线性回归，这表明在采样期间东亚大陆外流对西北太平洋上空大气PAHs具有主导作用。
