Field measurements of the atmospheric dry deposition fluxes and velocities of polycyclic aromatic hydrocarbons to the global oceans.
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.
Department of Environmental Chemistry, Institute of Environmental Assessment and Water Research, IDAEA-CSIC , Barcelona 08034, Catalunya Spain.
Belén
B
González-Gaya
Javier
J
Zúñiga-Rival
María-José
MJ
Ojeda
Begoña
B
Jiménez
Jordi
J
Dachs
D000336:Aerosols / Q000032:analysis; D000393:Air Pollutants / Q000032:analysis*; D001267:Atlantic Ocean; D001272:Atmosphere / Q000737:chemistry*; D004784:Environmental Monitoring; D005843:Geography; D019156:Indian Ocean; D038622:Internationality; D009792:Oceans and Seas; D010140:Pacific Ocean; D052638:Particulate Matter / Q000032:analysis; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis*; D012623:Seawater / Q000737:chemistry; D055549:Volatile Organic Compounds / Q000032:analysis
D000336:Aerosols; D000393:Air Pollutants; D052638:Particulate Matter; D011084:Polycyclic Aromatic Hydrocarbons; D055549:Volatile Organic Compounds