Articles | Volume 16, issue 10
Atmos. Chem. Phys., 16, 6381–6393, 2016
Atmos. Chem. Phys., 16, 6381–6393, 2016

Research article 25 May 2016

Research article | 25 May 2016

Bidirectional air–sea exchange and accumulation of POPs (PAHs, PCBs, OCPs and PBDEs) in the nocturnal marine boundary layer

Gerhard Lammel1,2, Franz X. Meixner3, Branislav Vrana1, Christos I. Efstathiou1, Jiři Kohoutek1, Petr Kukučka1, Marie D. Mulder1, Petra Přibylová1, Roman Prokeš1, Tatsiana P. Rusina1, Guo-Zheng Song3, and Manolis Tsapakis4 Gerhard Lammel et al.
  • 1Masaryk University, Research Centre for Toxic Compounds in the Environment, Brno, Czech Republic
  • 2Max Planck Institute for Chemistry, Multiphase Chemistry Dept., Mainz, Germany
  • 3Max Planck Institute for Chemistry, Biogeochemistry Dept., Mainz, Germany
  • 4Hellenic Centre for Marine Research, Institute of Oceanography, Gournes, Greece

Abstract. As a consequence of long-range transported pollution, air–sea exchange can become a major source of persistent organic pollutants in remote marine environments. The vertical gradients in the air were quantified for 14 species, i.e. four parent polycyclic aromatic hydrocarbons (PAHs), three polychlorinated biphenyls (PCBs), three organochlorine pesticides (OCPs) and two polybrominated diphenylethers (PBDEs) in the gas-phase at a remote coastal site in the southern Aegean Sea in summer. Most vertical gradients were positive (Δc∕Δz > 0), indicating downward (net depositional) flux. Significant upward (net volatilisational) fluxes were found for three PAHs, mostly during daytime, and for two OCPs, mostly during night-time, as well as for one PCB and one PBDE during part of the measurements. While phenanthrene was deposited, fluoranthene (FLT) and pyrene (PYR) seem to undergo flux oscillation, hereby not following a day–night cycle. Box modelling confirms that volatilisation from the sea surface has significantly contributed to the night-time maxima of OCPs. Fluxes were quantified based on eddy covariance. Deposition fluxes ranged from −28.5 to +1.8 µg m−2 day−1 for PAHs and −3.4 to +0.9 µg m−2 day−1 for halogenated compounds. Dry particle deposition of FLT and PYR did not contribute significantly to the vertical flux.

Short summary
As a consequence of long-range transported pollution air–sea exchange can become a major source of anthropogenic organic pollutants. Fluxes were studied at a remote coastal site in the Mediterranean, based on gradient measurements in air, measurements in surface seawater and eddy covariance. Night-time maxima in air are explained by volatilisation from the sea surface. Fluctuation of the direction of air–sea exchange indicate that long-term observations are needed.
Final-revised paper