Temporal variability of the carbonate system and air-sea CO2 exchanges in a Mediterranean human-impacted coastal site. (5th May 2020)

• Record Type: Journal Article
• Authors: Wimart-Rousseau, Cathy; Lajaunie-Salla, Katixa; Marrec, Pierre; Wagener, Thibaut; Raimbault, Patrick; Lagadec, Véronique; Lafont, Michel; Garcia, Nicole; Diaz, Frédéric; Pinazo, Christel; Yohia, Christophe; Garcia, Fabrice; Xueref-Remy, Irène; Blanc, Pierre-Eric; Armengaud, Alexandre; Lefèvre, Dominique
• Is Part Of: Estuarine, coastal and shelf science. Volume 236(2020)
• Publication Date: 2020-05-05
• Subjects: Coastal biogeochemistry -- CO2 fluxes -- Carbonate system -- North Western Mediterranean Sea -- Bay of Marseille; Estuarine oceanography -- Periodicals; Coasts -- Periodicals; Estuarine biology -- Periodicals; Seashore biology -- Periodicals; Coasts; Estuarine biology; Estuarine oceanography; Seashore biology; Periodicals; 551.461805
• DOI: 10.1016/j.ecss.2020.106641
• Languages: English
• ISSNs: 0272-7714

Abstract

Abstract: The temporal evolution of the carbonate system and air-sea CO2 fluxes are investigated for the first time in the Bay of Marseille (BoM – North Western Mediterranean Sea), a coastal system affected by anthropogenic forcing from the Marseille metropolis. This study presents a two-year time-series (between 2016 and 2018) of fortnightly measurements of AT, CT, pH and derived seawater carbonate parameters at the SOLEMIO station. On this land-ocean boundary area, no linear relationship between AT and salinity in surface water is observed due to sporadic intrusions of freshwater coming from the Rhone River. On an annual scale, the BoM acts as a sink of atmospheric CO2 . This result is consistent with previous studies in the Mediterranean Sea. Mean daily air-sea CO2 fluxes range between −0.8 mmolC.m −2 .d −1 and -2.2 mmolC.m −2 .d −1 during the study period, depending on the atmospheric CO2 sampling site used for the estimates. This study shows that the p CO2 in the surface water is predominantly driven by temperature changes, even if partially counterbalanced by biological activity. Therefore, temperature is the main contributor to the air-sea CO2 exchange variability. Mean daily Net Ecosystem Production (NEP) estimates from CT budget shows an ecosystem in which autotrophic processes are associated with a sink of CO2 . Despite some negative NEP values, the observed air-sea CO2 fluxes in the BoM are negative, suggesting that thermodynamic processes are the predominant drivers for these fluxes. Highlights: First study of the variability of the carbonate system in the Bay of Marseille. The Bay of Marseille acts as a sink of atmospheric CO2 at the annual scale. Temperature is the main contributor to the air-sea CO2 exchange variability.