Distribution and dynamics of Ωarag were investigated in the southern Yellow Sea of China.
Enhanced biological production increased surface water Ωarag to 3.8 in the southern SYS in summer.
Community respiration and/or aerobic remineralization dominated low Ωarag in subsurface waters.
Water stratification influenced the level and scale of acidity accumulation.
Waters with Ωarag > 2.0 could disappear from the SYS by the end of this century.