Seven ph tha late (PAEs) and nine organophos phate es ters (OPEs) were mea sured in sur face sed i ments across the Gulf of Lion (NW Mediter ranean Sea) at twelve sta tions char ac ter ized by dif fer ent an thro pogenic sig natures. ∑PAEs and ∑OPEs con cen tra tions ranged from 2 to 766 ng/ g DW (av. 196 ng/ g DW) and from 4 to 227 ng/ g DW (av. 54 ng/ g DW), re spec tively. Our analy sis of the po ten tial sources of these or ganic plas tic ad di tives in sed i ments of the Gulf of Lion sug gests that the dom i nant fac tors af fect ing their oc cur rence and en vi ron men tal dis tri b u tion are port-based in dus trial ac tiv i ties and ur ban pres sures. In deed, the high est ∑PAEs and ∑OPEs con cen tra tions were found close to the ports of Toulon and Mar seille (Es taque) and at the sites im pacted by the Mar seille met ro pol i tan area (i.e. at the out lets of the waste wa ter treat ment plant at Cor tiou and at the mouth of the Hu veaune River). The low est lev els were gen er ally found in pro tected ar eas (e.g. Port-Cros) and at sites rel a tively far from the coast. DEHP was seen to be the most abun dant PAE while TDCP, TEHP and TiBP were the most abun dant OPEs in the area. Our re sults also ex pose the con tribu tion of ad di tives en ter ing the Gulf of Lion via sed i men tary ma te r ial from the Rhône River, with pos i tive cor re la tions be tween the to tal or ganic car bon (TOC) con tent in the sed i ment and the ∑PAEs and ∑OPEs con cen tra tions. How ever, ad di tive con cen tra tions de creased from shore to o" shore in the Rhône River discharge area, in di cat ing an ef # cient di lu tion of the con t a m i nants ac cu mu lated at the river mouth area.

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Abstract. The Bay of Marseille (BoM, France) is impacted by the urbanized and industrialized Aix-Marseille Metropolis, which is subject to significant increases in anthropogenic emissions of CO2. A carbonate chemistry balance module has been implemented into a biogeochemical model of the planktonic food web. The resulting model, named Eco3M-CarbOx includes 22 states variables that are dispatched into 5 compartments: phytoplankton, heterotrophic bacteria, detritus, dissolved organic and inorganic matter. The model suggests that the variability of the dissolved inorganic carbon system is mainly driven by the seawater temperature dynamics. A seasonal trend is identified by the model and it shows that, during the mixed water column period, the BoM is a sink for atmospheric CO2 and a net autotroph ecosystem, while during stratified water column period, the BoM is a source of CO2 to the atmosphere and a net heterotroph ecosystem. External forcings have an important impact on the carbonate equilibrium. Wind events change seawater temperature quickly, as during upwelling, for which the BoM waters change within a few days from a source of CO2 to the atmosphere to a sink into the ocean. Moreover, the higher the wind speed is, the higher the air-sea CO2 gas exchange fluxes are. The river intrusions with nitrate and alkalinity supplies lead to a decrease in the pCO2 value, favoring the conditions of a sink of atmospheric CO2 into the BoM. The nearby highly urbanized environment of the Aix-Marseille metropolis produces strong atmospheric values of CO2, also favoring the conditions of a sink of atmospheric CO2 into the waters of the BoM.

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