An oxygen-containing blowing device for use in a wet flue gas desulfurizer for removing SO2 from combustion exhaust gas by wet desulfurization includes a fluid reservoir for an absorbing fluid equipped with a delivery pipe for discharging the absorbing fluid so that its discharge end is open in said fluid reservoir, and an oxygen feed nozzle for injecting an oxygen-containing gas disposed in the area of the discharged stream in the discharge end of the delivery pipe.