|Occurrence, loading and exposure of atmospheric particle-bound POPs at the African and European edges of the western Mediterranean Sea. |
(Article) Publié: Environmental Science And Technology, vol. p.10.1021/acs.est.7b04614 (2017)
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A comparative study for 62 toxic chemicals based on the monthly simultaneous collection of aerosol samples during 2015-2016 in two coastal cities at both the African (Bizerte, Tunisia) and European (Marseille, France) edges of the W Mediterranean basin is presented. Legacy polychlorinated biphenyls (Σ18PCBs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (Σ17PCDD/Fs) show generally higher median levels at the African edge (2.1 and 0.2 pg m-3, respectively) compared to the European coastal site (1.0 and 0.08 pg m-3, respectively). Contrary, the “emerging” polybrominated diphenyl ethers (Σ27PBDEs) median concentrations were higher in Marseille (~ 9.0 pg m-3) compared to Bizerte (~ 6.0 pg m-3). Different past usage and current emission patterns were found at both edges of the W Mediterranean, most probably linked to the respective different regulatory frameworks for toxic chemicals. Our results indicate that the total organic carbon (TOC) and/or the elemental carbon (EC) contents in the atmospheric aerosol may have a stronger effect than the total suspended particle (TSP) content as a whole on the spatial-temporal variability and the long-range atmospheric transport potential of the studied POPs. A “jumping” of the PBDE local atmospheric stocks from the NW European Mediterranean edge to the NW African coast seems to be possible under favorable conditions at present. While a higher PBDE median loading is estimated for Marseille area (~ 550 ng m-2 y-1) compared to Bizerte (~400 ng m-2 y-1), the median PCB and PCDD/F dry deposition fluxes were higher at the African site, resulting in a 3-fold higher toxic equivalent (TEQ) loading of dioxin-like pollutants (400 pg TEQ m-2 y-1) compared to Marseille (~140 pg TEQ m-2 y-1) with potential implications for the aquatic organisms. However, the inhalation exposure assessment points to a minimum risk for human health at both sites.