Sources, Transport and Deposition of Atmospheric Organic Pollutants in the Mediterranean Sea

Abstract : In this chapter a compilation of existing atmospheric concentration data and related deposition fluxes of organic contaminants in the Mediterranean Sea (far from the shore line) are presented. We have emphasized in compiling and discussing available data at open sea and background coastal sites which are most often scarce, but very valuable. The main objectives of this work were (a) to establish base line atmospheric concentrations of persistent organic pollutants (POPs) over the open Mediterranean Sea and to assess their spatial variability and potential sources based on existing data; (b) to estimate a total atmospheric load of POPs and related compounds at open sea based on most recent reported data. This literature review reveals that there is still a general lack of data on POPs and related contaminants in the atmosphere over the Mediterranean Sea as well as on their deposition fluxes, in particular at open sea. This data scarcity is more pronounced for organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs). This situation could have been motivated in part by the fact that existing national and international regulations and programmes dealing with marine pollution control and monitoring have relegated the atmospheric pathway to a second tier, if considered at all. The small amount of existing data does not allow identification of consistent trends. Atmospheric levels of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) seem to be homogeneous across the Mediterranean Sea, even comparable with those of big coastal cities, suggesting that even if there are hot spots in the Mediterranean basin the levels found at open sea are mostly driven by the atmospheric circulation patterns. Concentrations of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in the atmosphere over the Mediterranean Sea seem to be within the levels first measured in the 1980s, while a general declining trend was observed for hexachlorocyclohexanes (HCHs). Available data on PBDEs suggest that background costal sites in the Eastern Mediterranean may be considered as the least polluted areas at present. Moreover, coastal sites in the Western Mediterranean may present levels comparable to those reported for some of the largest urban coastal sites in the Mediterranean Region. The total atmospheric loading of organic contaminants (PAHs + OCPs + PCBs + PBDEs + PCDD/Fs) to open Mediterranean Sea waters is estimated to vary from 2100 to 4360 tons each year. It is important to note that even if PAHs are the predominant contaminants inputted to Mediterranean waters, other highly toxic chemicals are also entering the water masses via the atmosphere forming a complex cocktail of contaminants. Available data show that the Mediterranean waters are not only a sink for organic contaminants but also a source, with 200-1500 tons of organic contaminants (sum of all contaminant groups) “escaping” each year to the overlying atmosphere. Interestingly, data point to volatilization of toxic contaminants from open sea waters occurring at a higher extent in the Eastern Mediterranean Basin.
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https://hal.archives-ouvertes.fr/hal-02080796
Contributor : Javier Castro Jiménez <>
Submitted on : Wednesday, March 27, 2019 - 9:11:34 AM
Last modification on : Wednesday, August 7, 2019 - 11:44:06 AM

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Javier Castro-Jiménez, Naiara Berrojalbiz, Laurance Mejanelle, Jordi Dachs. Sources, Transport and Deposition of Atmospheric Organic Pollutants in the Mediterranean Sea. In Occurrence, Fate and Impact of Atmospheric Pollutants on Environmental and Human Health; McConnell, L., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2013., pp.231-260, 2013, ⟨10.1021/bk-2013-1149.ch011⟩. ⟨hal-02080796⟩

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