Polychlorinated Dibenzo-p-Dioxins and Dibenzofurans (PCDD/Fs) over the Mediterranean Sea

The marine environment is subjected to contamination by a wide spectrum of chemicals mainly due to anthropogenic activities. Among these chemicals, persistent organic pollutants (POPs) have gained a lot of attention in the last decades due to their ubiquity in many environmental compartments, and their adverse health effects in biota and humans. Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) are a family of POPs formed by 209 congeners. Seventeen of these congener have been described as the most toxic ones (2,3,7,8-substituted congeners) being able to bioaccumulate and enter the foowebs. Although certain amount of information on environmental levels and processes of PCDD/Fs is available for coastal areas, very little is known about their levels and behaviour far from the shore line (open seas). In this work environmental air concentrations and spatial distribution on PCDD/Fs across the Mediterranean Sea are presented. Data were collected during a sampling cruise (from Barcelona to Istanbul on board of the B/O Garcia del Cid, CSIC) performed within the framework of the IP THRESHOLDS of Environmental Sustainability. A distance of 3850 nautical miles (~ 7100km) was covered and a total of 5 transects were sampled along the Mediterranean and Marmara and Black seas. Air samples (particulate + gas phase) were collected by using two high volume samplers installed on the upper deck of the boat (around 6-7 m above the sea level) close to the bow. The samplers, operating in parallel, were equipped with a wind direction interface that stopped the sampling when wind was blowing from the poop of the vessel in order to avoid possible contaminations from the ship exhausts. Quartz fibre filters (QFFs) were used for air particle phase collection whereas compounds in the gas phase were trapped by using polyurethane foam (PUF) plugs. Samples were Soxhlet extracted with n-hexane/acetone after being spiked with internal standards, cleaned-up and analysed by high resolution gas chromatography–high resolution mass spectrometry (HRGC-HRMS). Isotopic dilution technique was used for quantification of target compounds according to 1613 U.S. EPA method. PCDD/F (∑17 toxic congeners) ambient air concentrations (particulate +gas phase) in the 4 transects along the Mediterranean Sea ranged from 114 to 813 fg m-3 (3-7 WHO98-TEQ fg m-3). The one sample transect collected at Marmara and Black Seas exhibited a higher PCDD/F concentration of 1555 fg m-3 (15 WHO98-TEQ fg m-3). Congener patters obtained were in general typical from distant sources with a predominance of the higher chlorinated dioxins (HpCDD and OCDD). The results from this campaign constitute a unique data set since no data on PCDD/Fs ambient air concentration across the Mediterranean Sea has been reported to date. Analyses of water samples, also collected during the campaign, are undergoing and will help to complete the picture and better understand the current status of contamination of this marine environment by PCDD/Fs.JRC.H.5-Rural, water and ecosystem resource