In September 2003, the highly turbid Loire estuary (France) showed drastic oxygen depletions (down to 11% of saturation), high pCO2 (up to 3740 ¿atm) and high CO2 fluxes (280 ¿ 100 mmol.m-2.d-1). A rapid rise in Dissolved Inorganic Carbon (DIC) was observed when the tidal amplitude increased from 3.8 m to 5.8 m. In two days, average concentrations in the 0.1--25 salinity range increased by 106 ¿ 17 ¿mol.kg-1 for DIC, by 80 ¿ 14 ¿eq.kg-1 for Total Alkalinity (TA) and by 684 ¿ 142 ¿atm for pCO2. In parallel, oxygen decreased by 65 ¿ 12 ¿mol.kg-1. These changes in concentrations were attributed in majority to a massive fluid mud resuspension in the estuarine turbidity maximum. At spring tide, this DIC input was 30% higher than the river input. When averaged over the neap-spring period, resuspension contributed to only 10% of the atmospheric CO2 flux from the estuary, but to 60% to the net TA production in the estuary.