Atmospheric Occurrence and Deposition of Polychlorinated Dibenzo- p -Dioxins and Dibenzofurans (PCDD/Fs) in the Open Mediterranean Sea

International audienceThe overall objective of this work is to provide the firstevaluation of polychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs) occurrence and deposition to Mediterraneanopen seawater. Σ2,3,7,8-PCDD/F air (gas+aerosol) concentrationsover the Mediterranean Sea ranged from 60 to1040fg m-3. The highest value (1555 fg m-3) was measured in areference sample taken in the SW Black Sea. No consistenttrend regarding the diel cycle of PCDD/Fswasobserved.PCDD/Fs transported to the open sea waters from continental areasand across the Atlantic as well as ship emissions may besignificant sources to the open Mediterranean. Seawaterconcentrations in the Mediterranean ranged from 42 to 64 fgL-1. The Σ2,3,7,8-PCDD/F dry deposition fluxes in theMarmara and Black Seas (210 kg year-1) are from 2 to 55times higher than dry fluxes in the Mediterranean Sea (4-156kg year-1). Analysis of estimated diffusive air-water fluxesand air/water fugacity ratios show that a net volatilization ofsome PCDD congeners is feasible. However, evidence of anet absorption flux for the rest of PCDD/F is found. When bothatmospheric deposition processes are considered togetherthe open Mediterranean Sea is a net sink of PCDD/F, due tothe importance of dry deposition fluxes of aerosol-boundPCDDFs