Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research, IDAEA-CSIC , Barcelona 08034, Catalunya Spain.
Environ Sci Technol. 2014 May 20;48(10):5583-92. doi: 10.1021/es500846p. Epub 2014 Apr 28.
The atmospheric dry deposition fluxes of 16 polycyclic aromatic hydrocarbons (PAHs) have been measured, for the first time, in the tropical and subtropical Atlantic, Pacific, and Indian Oceans. Depositional fluxes for fine (0.7-2.7 μm) and coarse (>2.7 μm) aerosol fractions were simultaneously determined with the suspended aerosol phase concentrations, allowing the determination of PAH deposition velocities (vD). PAH dry deposition fluxes (FDD) bound to coarse aerosols were higher than those of fine aerosols for 83% of the measurements. Average FDD for total (fine + coarse) Σ16PAHs (sum of 16 individual PAHs) ranged from 8.33 ng m(-2)d(-1) to 52.38 ng m(-2)d(-1). Mean FDD for coarse aerosol's individual PAHs ranged between 0.13 ng m(-2)d(-1) (Perylene) and 1.96 ng m(-2)d(-1) (Methyl Pyrene), and for the fine aerosol fraction these ranged between 0.06 ng m(-2)d(-1) (Dimethyl Pyrene) and 1.25 ng m(-2)d(-1) (Methyl Chrysene). The estimated deposition velocities went from the highest mean vD for Methyl Chrysene (0.17-13.30 cm s(-1)), followed by Dibenzo(ah)Anthracene (0.29-1.38 cm s(-1)), and other high MW PAHs to minimum values of vD for Dimethyl Pyrene (<0.04 cm s(-1)) and Pyrene (<0.06 cm s(-1)). Dry depositional processes depend on the concentration of PAHs in the suspended aerosol, but also on physicochemical properties and environmental variables (vapor pressure, wind speed, and on the affinity of aerosols for depositing to the sea surface). Empirical parametrizations are proposed to predict the dry depositional velocities of semivolatile organic compounds to the global oceans.
大气中 16 种多环芳烃（PAHs）的干沉降通量首次在热带和亚热带大西洋、太平洋和印度洋进行了测量。同时测定了细颗粒（0.7-2.7μm）和粗颗粒（>2.7μm）气溶胶相浓度的沉积通量，从而确定了 PAH 的沉积速度（vD）。在 83%的测量中，粗颗粒气溶胶结合的 PAH 干沉降通量（FDD）高于细颗粒气溶胶。总（细+粗）Σ16PAHs（16 种单体 PAHs 的总和）的平均 FDD 范围为 8.33ngm-2d-1至 52.38ngm-2d-1。粗颗粒气溶胶中各单体 PAH 的平均 FDD 范围为 0.13ngm-2d-1（苝）至 1.96ngm-2d-1（甲基苊），而细颗粒气溶胶的范围为 0.06ngm-2d-1（二甲基芘）至 1.25ngm-2d-1（甲基屈）。估算的沉积速度从甲基苊（0.17-13.30cms-1）的最高平均 vD 开始，随后是二苯并（ah）蒽（0.29-1.38cms-1）和其他高 MW PAHs，最后是二甲基芘（<0.04cms-1）和芘（<0.06cms-1）的最小 vD 值。干沉积过程不仅取决于悬浮气溶胶中 PAHs 的浓度，还取决于物理化学性质和环境变量（蒸气压、风速以及气溶胶对海表面沉积的亲和力）。提出了经验参数化方法来预测半挥发性有机化合物对全球海洋的干沉积速度。
